├── .github
└── workflows
│ ├── ci.yml
│ └── python-publish.yml
├── .gitignore
├── .readthedocs.yaml
├── LICENSE
├── README.md
├── assets
└── logo_3.png
├── docs
├── advanced-features.md
├── api
│ ├── compute-signal.md
│ ├── effect.md
│ ├── signal.md
│ └── utils.md
├── assets
│ └── logo_3.png
├── core-concepts.md
├── examples
│ └── index.md
├── index.md
├── installation.md
├── operators.md
├── quickstart.md
├── requirements.txt
└── why-reaktiv.md
├── examples
├── fastapi_websocket.py
├── iot_sensor_agent_thread.py
├── iot_temp_monitor.py
├── napkin_calc.py
├── nicegui_todo_app.py
├── numpy_plotting.py
├── polling_system.py
├── reactive_excel.py
├── reactive_jupyter_notebook.ipynb
└── stock_ticker.py
├── mkdocs.yml
├── pyproject.toml
├── pyrightconfig.json
├── src
└── reaktiv
│ ├── __init__.py
│ ├── core.py
│ ├── operators.py
│ └── utils.py
├── tests
├── test_batch_notifications.py
├── test_custom_equality.py
├── test_effect_triggers.py
├── test_lazy_computed.py
├── test_operator_chaining.py
├── test_operators.py
└── test_signals.py
└── uv.lock
/.github/workflows/ci.yml:
--------------------------------------------------------------------------------
1 | name: CI
2 |
3 | on:
4 | push:
5 | branches: [ "**" ] # Trigger on pushes to all branches
6 | pull_request:
7 | branches: [ "**" ] # Also trigger on pull requests to all branches
8 |
9 | permissions:
10 | contents: read
11 |
12 | jobs:
13 | test-and-build:
14 | runs-on: ubuntu-latest
15 | strategy:
16 | matrix:
17 | # Test against the minimum supported Python version and the latest stable version
18 | python-version: ['3.9', '3.12']
19 |
20 | steps:
21 | - uses: actions/checkout@v4
22 |
23 | - name: astral-sh/setup-uv
24 | uses: astral-sh/setup-uv@v5.3.1
25 | with:
26 | python-version: 3.9
27 |
28 | - name: Run Pyright
29 | run: |
30 | uv run pyright src/
31 |
32 | - name: Run tests
33 | run: |
34 | uv run pytest tests/
35 |
36 | - name: Build package
37 | run: |
38 | uv build
--------------------------------------------------------------------------------
/.github/workflows/python-publish.yml:
--------------------------------------------------------------------------------
1 | # This workflow will upload a Python Package to PyPI when a release is created
2 | # For more information see: https://docs.github.com/en/actions/automating-builds-and-tests/building-and-testing-python#publishing-to-package-registries
3 |
4 | # This workflow uses actions that are not certified by GitHub.
5 | # They are provided by a third-party and are governed by
6 | # separate terms of service, privacy policy, and support
7 | # documentation.
8 |
9 | name: Upload Python Package
10 |
11 | on:
12 | release:
13 | types: [published]
14 |
15 | permissions:
16 | contents: read
17 | id-token: write
18 |
19 | jobs:
20 | release-build:
21 | runs-on: ubuntu-latest
22 |
23 | steps:
24 | - uses: actions/checkout@v4
25 |
26 | - name: astral-sh/setup-uv
27 | uses: astral-sh/setup-uv@v5.3.1
28 | with:
29 | python-version: 3.9
30 |
31 | - name: Run Pyright
32 | run: |
33 | uv run pyright src/
34 |
35 | - name: Run tests
36 | run: |
37 | uv run pytest tests/
38 |
39 | - name: Build package
40 | run: |
41 | uv build
42 |
43 | - name: Publish to PyPi
44 | env:
45 | UV_PUBLISH_TOKEN: ${{ secrets.UV_PUBLISH_TOKEN }}
46 | run: |
47 | uv publish
48 |
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/.gitignore:
--------------------------------------------------------------------------------
1 | # Python-generated files
2 | __pycache__/
3 | *.py[oc]
4 | build/
5 | dist/
6 | wheels/
7 | *.egg-info
8 |
9 | # Virtual environments
10 | .venv
11 |
--------------------------------------------------------------------------------
/.readthedocs.yaml:
--------------------------------------------------------------------------------
1 | # Read the Docs configuration file
2 | # See https://docs.readthedocs.io/en/stable/config-file/v2.html for details
3 |
4 | # Required
5 | version: 2
6 |
7 | # Set the OS, Python version, and other tools you might need
8 | build:
9 | os: ubuntu-24.04
10 | tools:
11 | python: "3.13"
12 |
13 | # Build documentation with Mkdocs
14 | mkdocs:
15 | configuration: mkdocs.yml
16 |
17 | # Optionally, but recommended,
18 | # declare the Python requirements required to build your documentation
19 | # See https://docs.readthedocs.io/en/stable/guides/reproducible-builds.html
20 | python:
21 | install:
22 | - requirements: docs/requirements.txt
23 |
--------------------------------------------------------------------------------
/LICENSE:
--------------------------------------------------------------------------------
1 | MIT License
2 |
3 | Copyright (c) 2025 Tuan Anh Bui
4 |
5 | Permission is hereby granted, free of charge, to any person obtaining a copy
6 | of this software and associated documentation files (the "Software"), to deal
7 | in the Software without restriction, including without limitation the rights
8 | to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
9 | copies of the Software, and to permit persons to whom the Software is
10 | furnished to do so, subject to the following conditions:
11 |
12 | The above copyright notice and this permission notice shall be included in all
13 | copies or substantial portions of the Software.
14 |
15 | THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
16 | IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
17 | FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
18 | AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
19 | LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
20 | OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
21 | SOFTWARE.
22 |
--------------------------------------------------------------------------------
/assets/logo_3.png:
--------------------------------------------------------------------------------
https://raw.githubusercontent.com/buiapp/reaktiv/cacce5c3105334b5e7fef928bf3e884176cecc55/assets/logo_3.png
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/docs/advanced-features.md:
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1 | # Advanced Features
2 |
3 | This page covers advanced features and techniques in reaktiv for building more sophisticated reactive systems.
4 |
5 | ## Custom Equality Functions
6 |
7 | By default, reaktiv uses identity comparison (`is`) to determine if a signal's value has changed. For more complex types, you can provide custom equality functions:
8 |
9 | ```python
10 | from reaktiv import Signal
11 |
12 | # Custom equality for dictionaries
13 | def dict_equal(a, b):
14 | if not isinstance(a, dict) or not isinstance(b, dict):
15 | return a == b
16 | if set(a.keys()) != set(b.keys()):
17 | return False
18 | return all(a[k] == b[k] for k in a)
19 |
20 | # Create a signal with custom equality
21 | user = Signal({"name": "Alice", "age": 30}, equal=dict_equal)
22 |
23 | # This won't trigger updates because the dictionaries are equal by value
24 | user.set({"name": "Alice", "age": 30})
25 |
26 | # This will trigger updates because the "age" value is different
27 | user.set({"name": "Alice", "age": 31})
28 | ```
29 |
30 | Custom equality functions are especially useful for:
31 |
32 | - Complex data structures like dictionaries, lists, or custom objects
33 | - Case-insensitive string comparison
34 | - Numerical comparison with tolerance (for floating-point values)
35 | - Domain-specific equality (e.g., comparing users by ID regardless of other attributes)
36 |
37 | ## Effect Cleanup
38 |
39 | Effects can register cleanup functions that will run before the next execution or when the effect is disposed:
40 |
41 | ```python
42 | from reaktiv import Signal, Effect
43 |
44 | counter = Signal(0)
45 |
46 | def counter_effect(on_cleanup):
47 | value = counter()
48 | print(f"Setting up for counter value: {value}")
49 |
50 | # Set up some resource or state
51 |
52 | # Define cleanup function
53 | def cleanup():
54 | print(f"Cleaning up for counter value: {value}")
55 | # Release resources, remove event listeners, etc.
56 |
57 | # Register the cleanup function
58 | on_cleanup(cleanup)
59 |
60 | # Create and schedule the effect
61 | logger = Effect(counter_effect)
62 |
63 | # Prints: "Setting up for counter value: 0"
64 |
65 | # Update the signal
66 | counter.set(1)
67 | # Prints: "Cleaning up for counter value: 0"
68 | # Prints: "Setting up for counter value: 1"
69 |
70 | # Dispose the effect
71 | logger.dispose()
72 | # Prints: "Cleaning up for counter value: 1"
73 | ```
74 |
75 | This pattern is useful for:
76 |
77 | - Managing subscriptions to external event sources
78 | - Releasing resources when values change or the effect is disposed
79 | - Setting up and tearing down UI elements in response to data changes
80 | - Cancelling pending operations when new values arrive
81 |
82 | ## Asynchronous Iteration
83 |
84 | The `to_async_iter` utility lets you use signals with `async for` loops:
85 |
86 | ```python
87 | import asyncio
88 | from reaktiv import Signal, to_async_iter
89 |
90 | async def main():
91 | counter = Signal(0)
92 |
93 | # Start a task that increments the counter
94 | async def increment_counter():
95 | for i in range(1, 5):
96 | await asyncio.sleep(1)
97 | counter.set(i)
98 |
99 | asyncio.create_task(increment_counter())
100 |
101 | # Use the signal as an async iterator
102 | async for value in to_async_iter(counter):
103 | print(f"Got value: {value}")
104 | if value >= 4:
105 | break
106 |
107 | asyncio.run(main())
108 | ```
109 |
110 | Output:
111 | ```
112 | Got value: 0
113 | Got value: 1
114 | Got value: 2
115 | Got value: 3
116 | Got value: 4
117 | ```
118 |
119 | This is useful for:
120 |
121 | - Building reactive data processing pipelines
122 | - Integrating with other async code
123 | - Responding to signal changes in event loops
124 | - Creating reactive streams of data
125 |
126 | ## Selective Dependency Tracking
127 |
128 | You can selectively control which signals create dependencies using `untracked`:
129 |
130 | ```python
131 | from reaktiv import Signal, Effect, untracked
132 |
133 | user_id = Signal(123)
134 | user_data = Signal({"name": "Alice"})
135 | show_details = Signal(False)
136 |
137 | def render_user():
138 | # Always creates a dependency on user_id
139 | id_value = user_id()
140 |
141 | # Only access user_data if show_details is true,
142 | # but don't create a dependency on show_details
143 | if untracked(lambda: show_details()):
144 | print(f"User {id_value}: {user_data()}")
145 | else:
146 | print(f"User {id_value}")
147 |
148 | # Create and schedule the effect
149 | display = Effect(render_user)
150 |
151 | # Update dependencies will trigger the effect
152 | user_id.set(456)
153 |
154 | # This update won't trigger the effect, even though it changes the output
155 | show_details.set(True)
156 | ```
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/docs/api/compute-signal.md:
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1 | # Computed Signal API
2 |
3 | The `Computed` class creates a signal that derives its value from other signals. It automatically tracks dependencies and updates when those dependencies change.
4 |
5 | ## Basic Usage
6 |
7 | ```python
8 | from reaktiv import Signal, Computed
9 |
10 | # Base signals
11 | x = Signal(10)
12 | y = Signal(20)
13 |
14 | # Computed signal that depends on x and y
15 | sum_xy = Computed(lambda: x() + y())
16 |
17 | print(sum_xy()) # 30
18 |
19 | # When a dependency changes, the computed value updates automatically
20 | x.set(15)
21 | print(sum_xy()) # 35
22 | ```
23 |
24 | ## Creation
25 |
26 | ```python
27 | Computed(compute_fn: Callable[[], T], default: Optional[T] = None, *, equal: Optional[Callable[[T, T], bool]] = None) -> ComputedSignal[T]
28 | ```
29 |
30 | Creates a new computed signal that derives its value from other signals.
31 |
32 | ### Parameters
33 |
34 | - `compute_fn`: A function that computes the signal's value. When this function accesses other signals by calling them, dependencies are automatically tracked.
35 | - `default`: An optional default value to use until the first computation and when computation fails due to an error.
36 | - `equal`: Optional custom equality function to determine if two computed values are considered equal.
37 |
38 | ### Returns
39 |
40 | A computed signal object that can be called to get its value.
41 |
42 | ## Methods
43 |
44 | ### Calling the computed signal
45 |
46 | ```python
47 | sum_xy() # equivalent to sum_xy.get()
48 | ```
49 |
50 | Returns the computed value, calculating it if necessary. When called within an active effect or another computed signal, it establishes a dependency relationship.
51 |
52 | **Returns**: The computed value.
53 |
54 | **Note**: A computed signal is lazy. It only computes its value when called, and it caches the result until dependencies change.
55 |
56 | ## Advanced Methods
57 |
58 | The following methods are typically used internally by the library:
59 |
60 | ### subscribe / unsubscribe
61 |
62 | These methods work the same as in regular signals and are usually used internally by the library.
63 |
64 | ## Error Handling
65 |
66 | When a computed signal's computation function raises an exception, the exception is propagated to the caller. This allows you to handle errors at the appropriate level in your application.
67 |
68 | ```python
69 | from reaktiv import Signal, Computed
70 |
71 | # Base signal
72 | x = Signal(10)
73 |
74 | # Computed signal with potential error
75 | result = Computed(lambda: 100 / x())
76 |
77 | print(result()) # 10 (100 / 10)
78 |
79 | # Set x to 0, which would cause a division by zero
80 | x.set(0)
81 |
82 | # The exception will be propagated to the caller
83 | try:
84 | print(result())
85 | except ZeroDivisionError as e:
86 | print(f"Caught error: {e}") # Prints: "Caught error: division by zero"
87 |
88 | # After fixing the dependency value, computation works again
89 | x.set(5)
90 | print(result()) # 20 (100 / 5)
91 | ```
92 |
93 | This transparent error propagation gives you full control over error handling in your application. You can:
94 |
95 | 1. Use try/except blocks where you access computed values
96 | 2. Let exceptions bubble up to a higher-level error handler
97 | 3. Use defensive programming in your computation functions
98 |
99 | ## Lazy Evaluation
100 |
101 | A key feature of computed signals is lazy evaluation. The computation function only runs:
102 |
103 | 1. The first time the signal is called
104 | 2. When dependencies have changed since the last computation
105 |
106 | This means expensive computations are only performed when necessary:
107 |
108 | ```python
109 | from reaktiv import Signal, Computed
110 |
111 | x = Signal(10)
112 | y = Signal(20)
113 |
114 | def expensive_computation():
115 | print("Computing...")
116 | return x() * y()
117 |
118 | result = Computed(expensive_computation)
119 |
120 | # Nothing happens yet - computation is lazy
121 |
122 | # First access - computation runs
123 | print(result()) # Prints: "Computing..." then "200"
124 |
125 | # Second access - no computation needed because nothing changed
126 | print(result()) # Just prints "200" (no "Computing..." message)
127 |
128 | # Change a dependency
129 | x.set(5)
130 |
131 | # Now accessing will recompute
132 | print(result()) # Prints: "Computing..." then "100"
133 | ```
134 |
135 | ## Note on ComputeSignal vs computed()
136 |
137 | While reaktiv provides both the `Computed` class (alias for `ComputeSignal`) and `computed()` shortcut function, the recommended approach is to use the `Computed` class directly for a more consistent API.
138 |
139 | The `computed()` function is deprecated and will be removed in a future version. It currently emits a deprecation warning:
140 |
141 | ```python
142 | # Deprecated approach (will show warning):
143 | from reaktiv import signal, computed
144 | x = signal(10)
145 | doubled = computed(lambda: x() * 2)
146 |
147 | # Recommended approach:
148 | from reaktiv import Signal, Computed
149 | x = Signal(10)
150 | doubled = Computed(lambda: x() * 2)
151 | ```
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/docs/api/effect.md:
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1 | # Effect API
2 |
3 | The `Effect` class creates side effects that automatically run when their dependencies change. Effects are useful for updating UI elements, logging, API calls, and other operations that respond to state changes.
4 |
5 | ## Basic Usage
6 |
7 | ```python
8 | from reaktiv import Signal, Effect
9 |
10 | # Create a signal
11 | counter = Signal(0)
12 |
13 | # Create an effect that runs when counter changes
14 | counter_effect = Effect(lambda: print(f"Counter: {counter()}"))
15 | # Immediately prints: "Counter: 0"
16 |
17 | # When the signal changes, the effect runs automatically
18 | counter.set(1)
19 | # Prints: "Counter: 1"
20 |
21 | # Clean up when done
22 | counter_effect.dispose()
23 | ```
24 |
25 | ## Creation
26 |
27 | ```python
28 | Effect(func: Callable[..., Union[None, Coroutine[None, None, None]]]) -> Effect
29 | ```
30 |
31 | Creates a new effect that automatically runs when its dependencies change.
32 |
33 | ### Parameters
34 |
35 | - `func`: A function or coroutine function to run when dependencies change. Dependencies are automatically tracked when this function accesses signals by calling them. If the function accepts a parameter, it receives an `on_cleanup` function.
36 |
37 | ### Returns
38 |
39 | An effect object that manages the execution of the function when dependencies change.
40 |
41 | ## Methods
42 |
43 | ### dispose
44 |
45 | ```python
46 | dispose() -> None
47 | ```
48 |
49 | Disposes of the effect, removing all dependencies and preventing it from running again.
50 |
51 | **Note**: You should call `dispose()` when an effect is no longer needed to prevent memory leaks.
52 |
53 | ## Asynchronous Effects
54 |
55 | reaktiv has first-class support for asynchronous effects:
56 |
57 | ```python
58 | import asyncio
59 | from reaktiv import Signal, Effect
60 |
61 | async def main():
62 | counter = Signal(0)
63 |
64 | async def log_counter():
65 | print(f"Counter value: {counter()}")
66 |
67 | # Create and schedule the async effect
68 | logger = Effect(log_counter) # Prints: "Counter value: 0"
69 |
70 | # Update the signal and wait for the effect to run
71 | counter.set(1)
72 | await asyncio.sleep(0) # Gives the effect time to execute
73 | # Prints: "Counter value: 1"
74 |
75 | # Clean up
76 | logger.dispose()
77 |
78 | asyncio.run(main())
79 | ```
80 |
81 | ## Cleanup Functions
82 |
83 | Effects can register cleanup functions that will be executed before the effect runs again or when it's disposed:
84 |
85 | ```python
86 | from reaktiv import Signal, Effect
87 |
88 | counter = Signal(0)
89 |
90 | def counter_effect(on_cleanup):
91 | value = counter()
92 | print(f"Counter value: {value}")
93 |
94 | # Register a cleanup function
95 | def cleanup():
96 | print(f"Cleaning up for value: {value}")
97 |
98 | on_cleanup(cleanup)
99 |
100 | # Create and schedule the effect with cleanup
101 | logger = Effect(counter_effect)
102 | # Prints: "Counter value: 0"
103 |
104 | # Update the signal
105 | counter.set(1)
106 | # Prints: "Cleaning up for value: 0"
107 | # Prints: "Counter value: 1"
108 |
109 | # Dispose the effect
110 | logger.dispose()
111 | # Prints: "Cleaning up for value: 1"
112 | ```
113 |
114 | ## Memory Management
115 |
116 | Effects are not automatically garbage collected as long as they're actively tracking dependencies. To prevent memory leaks:
117 |
118 | 1. Keep a reference to your effect as long as you need it
119 | 2. Call `dispose()` when you're done with the effect
120 | 3. Avoid creating effects inside loops or frequently-called functions without disposing of them
121 |
122 | ```python
123 | from reaktiv import Signal, Effect
124 |
125 | def create_temporary_effect(s):
126 | # This effect will only exist while the function runs
127 | temp_effect = Effect(lambda: print(f"Value: {s()}"))
128 | # ... do something ...
129 | temp_effect.dispose() # Clean up properly
130 |
131 | # Better pattern for component lifecycle
132 | class MyComponent:
133 | def __init__(self, s):
134 | self.s = s
135 | self.effect_instance = Effect(self._render)
136 |
137 | def _render(self):
138 | print(f"Rendering: {self.s()}")
139 |
140 | def destroy(self):
141 | self.effect_instance.dispose()
142 | ```
143 |
144 | ## Notification Batching
145 |
146 | When multiple signals change, their effects are batched to avoid unnecessary executions:
147 |
148 | ```python
149 | from reaktiv import Signal, Effect, batch
150 |
151 | x = Signal(1)
152 | y = Signal(2)
153 |
154 | def log_values():
155 | print(f"x: {x()}, y: {y()}")
156 |
157 | logger = Effect(log_values) # Prints: "x: 1, y: 2"
158 |
159 | # Without batching, the effect would run twice:
160 | # x.set(10) # Effect runs
161 | # y.set(20) # Effect runs again
162 |
163 | # With batching, the effect runs only once after all changes:
164 | with batch():
165 | x.set(10) # No effect execution yet
166 | y.set(20) # No effect execution yet
167 | # After batch completes: Effect runs once with new values
168 | # Prints: "x: 10, y: 20"
169 | ```
170 |
171 | ## Note on Effect vs effect()
172 |
173 | While reaktiv provides both the `Effect` class and `effect()` shortcut function, the recommended approach is to use the `Effect` class directly for a more consistent API.
174 |
175 | The `effect()` function is deprecated and will be removed in a future version. It currently emits a deprecation warning:
176 |
177 | ```python
178 | # Deprecated approach (will show warning):
179 | from reaktiv import signal, effect
180 | count = signal(0)
181 | count_effect = effect(lambda: print(f"Count: {count()}"))
182 |
183 | # Recommended approach:
184 | from reaktiv import Signal, Effect
185 | count = Signal(0)
186 | count_effect = Effect(lambda: print(f"Count: {count()}"))
187 | ```
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/docs/api/signal.md:
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1 | # Signal API
2 |
3 | The `Signal` class is the core building block in reaktiv. It creates a container for values that can change over time and notify dependents of those changes.
4 |
5 | ## Basic Usage
6 |
7 | ```python
8 | from reaktiv import Signal
9 |
10 | # Create a signal with an initial value
11 | counter = Signal(0)
12 |
13 | # Get the current value
14 | value = counter() # 0
15 |
16 | # Set a new value
17 | counter.set(5)
18 |
19 | # Update using a function
20 | counter.update(lambda x: x + 1) # Now 6
21 | ```
22 |
23 | ## Creation
24 |
25 | ```python
26 | Signal(value: T, *, equal: Optional[Callable[[T, T], bool]] = None) -> Signal[T]
27 | ```
28 |
29 | Creates a new signal with an initial value.
30 |
31 | ### Parameters
32 |
33 | - `value`: The initial value of the signal.
34 | - `equal`: Optional custom equality function to determine if two values should be considered equal. By default, identity (`is`) is used.
35 |
36 | ### Returns
37 |
38 | A signal object that can be called to get its value and has methods to set and update its value.
39 |
40 | ## Methods
41 |
42 | ### Calling the signal
43 |
44 | ```python
45 | counter() # equivalent to counter.get()
46 | ```
47 |
48 | Returns the current value of the signal. When called within an active effect or computed signal, it establishes a dependency relationship.
49 |
50 | **Returns**: The current value of the signal.
51 |
52 | ### set
53 |
54 | ```python
55 | set(new_value: T) -> None
56 | ```
57 |
58 | Updates the signal's value and notifies subscribers if the value has changed.
59 |
60 | **Parameters**:
61 | - `new_value`: The new value to set.
62 |
63 | **Note**: A notification is triggered only if the new value is considered different from the current value. By default, identity comparison (`is`) is used unless a custom equality function was provided.
64 |
65 | ### update
66 |
67 | ```python
68 | update(update_fn: Callable[[T], T]) -> None
69 | ```
70 |
71 | Updates the signal's value by applying a function to its current value.
72 |
73 | **Parameters**:
74 | - `update_fn`: A function that takes the current value and returns the new value.
75 |
76 | ## Advanced Methods
77 |
78 | The following methods are typically used internally by the library and are not needed for most applications:
79 |
80 | ### subscribe
81 |
82 | ```python
83 | subscribe(subscriber: Subscriber) -> None
84 | ```
85 |
86 | Adds a subscriber to be notified when the signal's value changes.
87 |
88 | **Parameters**:
89 | - `subscriber`: An object implementing the `Subscriber` protocol with a `notify()` method.
90 |
91 | **Note**: This is typically used internally by the library. Most applications should use `effect()` or `compute()` instead.
92 |
93 | ### unsubscribe
94 |
95 | ```python
96 | unsubscribe(subscriber: Subscriber) -> None
97 | ```
98 |
99 | Removes a subscriber so it no longer receives notifications.
100 |
101 | **Parameters**:
102 | - `subscriber`: The subscriber to remove.
103 |
104 | **Note**: This is typically used internally by the library.
105 |
106 | ## Custom Equality Example
107 |
108 | ```python
109 | from reaktiv import Signal
110 |
111 | # Custom equality function for comparing dictionaries by value
112 | def dict_equal(a, b):
113 | if not isinstance(a, dict) or not isinstance(b, dict):
114 | return a == b
115 | if a.keys() != b.keys():
116 | return False
117 | return all(a[k] == b[k] for k in a)
118 |
119 | # Create a signal with custom equality
120 | user = Signal({"name": "Alice", "age": 30}, equal=dict_equal)
121 |
122 | # This won't trigger updates because the dictionaries have the same key-value pairs
123 | user.set({"name": "Alice", "age": 30})
124 |
125 | # This will trigger updates because the "age" value differs
126 | user.set({"name": "Alice", "age": 31})
127 | ```
128 |
129 | ## Note on Signal vs signal()
130 |
131 | While reaktiv provides both the `Signal` class and `signal()` shortcut function, the recommended approach is to use the `Signal` class directly for a more consistent API.
132 |
133 | The `signal()` function is deprecated and will be removed in a future version. It currently emits a deprecation warning:
134 |
135 | ```python
136 | # Deprecated approach (will show warning):
137 | from reaktiv import signal
138 | counter = signal(0)
139 |
140 | # Recommended approach:
141 | from reaktiv import Signal
142 | counter = Signal(0)
143 | ```
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1 | # Utilities API
2 |
3 | reaktiv provides several utility functions to enhance your reactive programming experience.
4 |
5 | ## batch
6 |
7 | ```python
8 | batch()
9 | ```
10 |
11 | A context manager that batches multiple signal updates together, deferring computations and effects until the batch completes.
12 |
13 | ### Usage
14 |
15 | ```python
16 | from reaktiv import signal, computed, effect, batch
17 |
18 | x = signal(5)
19 | y = signal(10)
20 | sum_xy = computed(lambda: x() + y())
21 |
22 | def log_sum():
23 | print(f"Sum: {sum_xy()}")
24 |
25 | logger = effect(log_sum) # Prints: "Sum: 15"
26 |
27 | # Without batching, this would trigger two separate updates:
28 | # x.set(10) # Triggers recomputation & effect
29 | # y.set(20) # Triggers recomputation & effect again
30 |
31 | # With batching, updates are processed together:
32 | with batch():
33 | x.set(10) # No immediate effect execution
34 | y.set(20) # No immediate effect execution
35 | # After batch completes, computations and effects run once
36 | # Prints: "Sum: 30"
37 | ```
38 |
39 | ### Benefits
40 |
41 | - **Performance**: Reduces unnecessary recomputations when multiple signals change together
42 | - **Consistency**: Ensures effects only see the final state after all updates are complete
43 | - **Atomicity**: Makes a series of updates appear as a single atomic change
44 |
45 | ## untracked
46 |
47 | ```python
48 | untracked(func: Callable[[], T]) -> T
49 | ```
50 |
51 | Executes a function without creating dependencies on any signals accessed within it.
52 |
53 | ### Parameters
54 |
55 | - `func`: The function to execute without tracking signal dependencies.
56 |
57 | ### Returns
58 |
59 | - The return value of the executed function.
60 |
61 | ### Usage
62 |
63 | ```python
64 | from reaktiv import signal, effect, untracked
65 |
66 | name = signal("Alice")
67 | greeting = signal("Hello")
68 |
69 | def log_message():
70 | # This creates a dependency on the 'name' signal
71 | person = name()
72 |
73 | # This does NOT create a dependency on the 'greeting' signal
74 | prefix = untracked(lambda: greeting())
75 |
76 | print(f"{prefix}, {person}!")
77 |
78 | logger = effect(log_message) # Prints: "Hello, Alice!"
79 |
80 | # This will trigger the effect because 'name' is a dependency
81 | name.set("Bob") # Prints: "Hello, Bob!"
82 |
83 | # This will NOT trigger the effect because 'greeting' is accessed via untracked()
84 | greeting.set("Hi") # No effect execution
85 | ```
86 |
87 | ### Use Cases
88 |
89 | - Accessing signals without creating dependencies
90 | - Reading configuration values that shouldn't trigger reactivity
91 | - Breaking circular dependencies
92 | - Optimizing performance by selectively tracking only necessary dependencies
93 |
94 | ## to_async_iter
95 |
96 | ```python
97 | to_async_iter(signal_instance) -> AsyncIterator[T]
98 | ```
99 |
100 | Converts a signal into an async iterator that yields values whenever the signal changes.
101 |
102 | ### Parameters
103 |
104 | - `signal_instance`: The signal to convert to an async iterator.
105 |
106 | ### Returns
107 |
108 | - An async iterator that yields the signal's value on each change.
109 |
110 | ### Usage
111 |
112 | ```python
113 | import asyncio
114 | from reaktiv import signal, to_async_iter
115 |
116 | async def main():
117 | counter = signal(0)
118 |
119 | # Create a task that increments the counter
120 | async def increment_counter():
121 | for i in range(1, 6):
122 | await asyncio.sleep(1)
123 | counter.set(i)
124 |
125 | # Start the counter task
126 | asyncio.create_task(increment_counter())
127 |
128 | # Use the counter signal as an async iterator
129 | async for value in to_async_iter(counter):
130 | print(f"Counter changed: {value}")
131 | if value >= 5:
132 | break
133 |
134 | asyncio.run(main())
135 | ```
136 |
137 | ### Output
138 |
139 | ```
140 | Counter changed: 0
141 | Counter changed: 1
142 | Counter changed: 2
143 | Counter changed: 3
144 | Counter changed: 4
145 | Counter changed: 5
146 | ```
147 |
148 | ### Use Cases
149 |
150 | - Integrating signals with async for loops
151 | - Processing signal values as a stream
152 | - Converting between signals and other async primitives
153 | - Building reactive data pipelines
154 | - Using signals with other async libraries
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1 | # Core Concepts
2 |
3 | This page explains the core concepts of reactive programming as implemented in the reaktiv library.
4 |
5 | ## Reactive Programming
6 |
7 | Reactive programming is a declarative programming paradigm concerned with data streams and the propagation of changes. With reaktiv, you define how your application state should be derived from its inputs, and the library takes care of updating everything when those inputs change.
8 |
9 | ## reaktiv's Core Primitives
10 |
11 | reaktiv provides three main primitives for reactive programming:
12 |
13 | ```mermaid
14 | graph TD
15 | %% Define node subgraphs for better organization
16 | subgraph "Data Sources"
17 | S1[Signal A]
18 | S2[Signal B]
19 | S3[Signal C]
20 | end
21 |
22 | subgraph "Derived Values"
23 | C1[Computed X]
24 | C2[Computed Y]
25 | end
26 |
27 | subgraph "Side Effects"
28 | E1[Effect 1]
29 | E2[Effect 2]
30 | end
31 |
32 | subgraph "External Systems"
33 | EXT1[UI Update]
34 | EXT2[API Call]
35 | EXT3[Database Write]
36 | end
37 |
38 | %% Define relationships between nodes
39 | S1 -->|"get()"| C1
40 | S2 -->|"get()"| C1
41 | S2 -->|"get()"| C2
42 | S3 -->|"get()"| C2
43 |
44 | C1 -->|"get()"| E1
45 | C2 -->|"get()"| E1
46 | S3 -->|"get()"| E2
47 | C2 -->|"get()"| E2
48 |
49 | E1 --> EXT1
50 | E1 --> EXT2
51 | E2 --> EXT3
52 |
53 | %% Change propagation path
54 | S1 -.-> |"1\. set()"| C1
55 | C1 -.->|"2\. recompute"| E1
56 | E1 -.->|"3\. execute"| EXT1
57 |
58 | %% Style nodes by type
59 | classDef signal fill:#4CAF50,color:white,stroke:#388E3C,stroke-width:1px
60 | classDef computed fill:#2196F3,color:white,stroke:#1976D2,stroke-width:1px
61 | classDef effect fill:#FF9800,color:white,stroke:#F57C00,stroke-width:1px
62 |
63 | %% Apply styles to nodes
64 | class S1,S2,S3 signal
65 | class C1,C2 computed
66 | class E1,E2 effect
67 |
68 | %% Legend node
69 | LEGEND[" Legend:
70 | • Signal: Stores a value, notifies dependents
71 | • Computed: Derives value from dependencies
72 | • Effect: Runs side effects when dependencies change
73 | • → Data flow / Dependency (read)
74 | • ⟿ Change propagation (update)
75 | "]
76 | classDef legend fill:none,stroke:none,text-align:left
77 | class LEGEND legend
78 | ```
79 |
80 | The diagram above illustrates how reaktiv's primitives interact:
81 |
82 | - **Signals** (green) store values and form the foundation of your reactive system
83 | - **Computed values** (blue) derive data from signals and other computed values
84 | - **Effects** (orange) perform side effects when their dependencies change
85 | - Arrows show both data flow (solid) and change propagation (dotted)
86 |
87 | ### 1. Signals
88 |
89 | Signals are containers for values that can change over time. They notify interested parties (subscribers) when their values change.
90 |
91 | ```python
92 | from reaktiv import Signal
93 |
94 | # Create a signal with initial value
95 | counter = Signal(0)
96 |
97 | # Get the current value
98 | value = counter() # 0
99 |
100 | # Set a new value
101 | counter.set(1)
102 |
103 | # Update using a function
104 | counter.update(lambda x: x + 1) # Now 2
105 | ```
106 |
107 | Signals are the fundamental building blocks in reaktiv. They:
108 |
109 | - Store a single value
110 | - Provide methods to get and set that value
111 | - Track dependencies that read their values
112 | - Notify dependents when their values change
113 |
114 | ### 2. Computed Signals
115 |
116 | Computed signals derive their values from other signals. They automatically update when their dependencies change.
117 |
118 | ```python
119 | from reaktiv import Signal, Computed
120 |
121 | # Base signals
122 | x = Signal(10)
123 | y = Signal(20)
124 |
125 | # Computed signal
126 | sum_xy = Computed(lambda: x() + y())
127 |
128 | print(sum_xy()) # 30
129 |
130 | # Change a dependency
131 | x.set(15)
132 |
133 | # Computed value updates automatically
134 | print(sum_xy()) # 35
135 | ```
136 |
137 | Key characteristics of computed signals:
138 |
139 | - Their values are derived from other signals
140 | - They automatically update when dependencies change
141 | - They're lazy - only computed when accessed
142 | - They track their own dependencies automatically
143 | - They only recompute when necessary
144 | - They cannot be set manually - they derive from their dependencies
145 |
146 | ### 3. Effects
147 |
148 | Effects run side effects (like updating UI, logging, or network calls) when signals change.
149 |
150 | ```python
151 | from reaktiv import Signal, Effect
152 |
153 | name = Signal("Alice")
154 |
155 | def log_name():
156 | print(f"Name changed to: {name()}")
157 |
158 | # Create and schedule the effect
159 | logger = Effect(log_name) # Prints: "Name changed to: Alice"
160 |
161 | # Change the signal
162 | name.set("Bob") # Prints: "Name changed to: Bob"
163 |
164 | # Clean up when done
165 | logger.dispose()
166 | ```
167 |
168 | Effects:
169 |
170 | - Execute a function when created and whenever dependencies change
171 | - Automatically track signal dependencies
172 | - Can be disposed when no longer needed
173 | - Support both synchronous and asynchronous functions
174 | - Can handle cleanup via the optional `on_cleanup` parameter
175 |
176 | Effects work with both synchronous and asynchronous functions, giving you flexibility based on your needs:
177 |
178 | ```python
179 | # Synchronous effect (no asyncio needed)
180 | counter = Signal(0)
181 | sync_effect = Effect(lambda: print(f"Counter: {counter()}")) # Runs immediately
182 |
183 | counter.set(1) # Effect runs synchronously
184 |
185 | # Asynchronous effect (requires asyncio)
186 | import asyncio
187 |
188 | async def async_logger():
189 | print(f"Async counter: {counter()}")
190 |
191 | async_effect = Effect(async_logger) # Schedules the effect in the event loop
192 | ```
193 |
194 | Choose synchronous effects when you don't need async functionality, and async effects when you need to perform async operations within your effects.
195 |
196 | ## Dependency Tracking
197 |
198 | reaktiv automatically tracks dependencies between Signals, Computed and Effects:
199 |
200 | ```python
201 | from reaktiv import Signal, Computed, Effect
202 |
203 | first_name = Signal("John")
204 | last_name = Signal("Doe")
205 |
206 | # This computed signal depends on both first_name and last_name
207 | full_name = Computed(lambda: f"{first_name()} {last_name()}")
208 |
209 | # This effect depends on full_name (and indirectly on first_name and last_name)
210 | display = Effect(lambda: print(f"Full name: {full_name()}"))
211 |
212 | # Changing either first_name or last_name will update full_name and trigger the effect
213 | first_name.set("Jane") # Effect runs
214 | ```
215 |
216 | The dependency tracking works by:
217 |
218 | 1. When a signal is accessed by calling it (e.g., `Signal()`), it checks if there's a currently active effect or computation
219 | 2. If found, the signal adds itself as a dependency of that effect or computation
220 | 3. When the signal's value changes, it notifies all its dependents
221 | 4. Dependents then update or re-execute as needed
222 |
223 | ## Batching
224 |
225 | When multiple signals change, reaktiv can batch the updates to avoid unnecessary recalculations:
226 |
227 | ```python
228 | from reaktiv import Signal, Computed, batch, Effect
229 |
230 | x = Signal(10)
231 | y = Signal(20)
232 | sum_xy = Computed(lambda: x() + y())
233 |
234 | def log_sum():
235 | print(f"Sum: {sum_xy()}")
236 |
237 | logger = Effect(log_sum) # Prints: "Sum: 30"
238 |
239 | # Without batching, each signal change would trigger recomputation
240 | # With batching, recomputation happens only once after all changes
241 | with batch():
242 | x.set(5) # No recomputation yet
243 | y.set(15) # No recomputation yet
244 | # After batch completes, prints: "Sum: 20"
245 | ```
246 |
247 | ## Memory Management
248 |
249 | reaktiv uses weak references for its internal subscriber tracking, which means:
250 |
251 | 1. Computed signals and effects are garbage collected when no longer referenced
252 | 2. You need to maintain a reference to your effects to prevent premature garbage collection
253 | 3. Call `dispose()` on effects when you're done with them to clean up resources
254 |
255 | ### Retaining Effects
256 |
257 | It's critical to retain (assign to a variable) all Effects to prevent garbage collection. If you create an Effect without assigning it to a variable, it may be immediately garbage collected:
258 |
259 | ```python
260 | # INCORRECT: Effect will be garbage collected immediately
261 | Effect(lambda: print(f"Value changed: {my_signal()}"))
262 |
263 | # CORRECT: Effect is retained
264 | my_effect = Effect(lambda: print(f"Value changed: {my_signal()}"))
265 | ```
266 |
267 | When using Effects in classes, assign them to instance attributes in the constructor to ensure they're retained throughout the object's lifecycle:
268 |
269 | ```python
270 | class TemperatureMonitor:
271 | def __init__(self, initial_temp=0):
272 | self._temperature = Signal(initial_temp)
273 |
274 | def _handle_temperature_change():
275 | current_temp = self._temperature()
276 | print(f"Temperature changed: {current_temp}°C")
277 | if current_temp > 30:
278 | print("Warning: Temperature too high!")
279 |
280 | # Assign Effect to self._effect to prevent garbage collection
281 | self._effect = Effect(_handle_temperature_change)
282 | ```
283 |
284 | ## Custom Equality
285 |
286 | By default, reaktiv uses identity (`is`) to determine if a signal's value has changed. This is important to understand because it affects how mutable objects behave in your reactive system.
287 |
288 | ### Identity vs. Value Equality
289 |
290 | With the default identity comparison:
291 |
292 | - Primitive values like numbers, strings, and booleans work as expected
293 | - For mutable objects like lists, dictionaries, or custom classes:
294 | - Creating a new object with the same content will be detected as a change
295 | - Modifying an object in-place won't be detected as a change
296 |
297 | ```python
298 | # With default identity equality
299 | items = Signal([1, 2, 3])
300 |
301 | # This WILL trigger updates (different list instance)
302 | items.set([1, 2, 3])
303 |
304 | # In-place modification WON'T trigger updates
305 | current = items()
306 | current.append(4) # Signal doesn't detect this change
307 | ```
308 |
309 | ### Customizing Equality Checks
310 |
311 | For collections or custom objects, you can provide a custom equality function:
312 |
313 | ```python
314 | # Custom equality for comparing lists by value
315 | def list_equal(a, b):
316 | if len(a) != len(b):
317 | return False
318 | return all(a_item == b_item for a_item, b_item in zip(a, b))
319 |
320 | # Create a signal with custom equality
321 | items = Signal([1, 2, 3], equal=list_equal)
322 |
323 | # This won't trigger updates because the lists have the same values
324 | items.set([1, 2, 3])
325 |
326 | # This will trigger updates because the values differ
327 | items.set([1, 2, 3, 4])
328 | ```
329 |
330 | For dictionaries:
331 |
332 | ```python
333 | def dict_equal(a, b):
334 | return a.keys() == b.keys() and all(a[k] == b[k] for k in a.keys())
335 |
336 | config = Signal({"theme": "dark", "font_size": 12}, equal=dict_equal)
337 |
338 | # Won't trigger updates (same content)
339 | config.set({"theme": "dark", "font_size": 12})
340 |
341 | # Will trigger updates (different content)
342 | config.set({"theme": "light", "font_size": 12})
343 | ```
344 |
345 | When working with mutable objects, you have two options:
346 | 1. Provide a custom equality function that compares by value
347 | 2. Always create new instances when updating (immutable approach)
348 |
349 | The immutable approach is often cleaner and less error-prone:
350 |
351 | ```python
352 | # Immutable approach with lists
353 | items = Signal([1, 2, 3])
354 |
355 | # Create a new list when updating
356 | items.update(lambda current: current + [4]) # [1, 2, 3, 4]
357 |
358 | # Immutable approach with dictionaries
359 | config = Signal({"theme": "dark"})
360 |
361 | # Create a new dict when updating
362 | config.update(lambda current: {**current, "font_size": 14})
363 | ```
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1 | # Real-World Examples
2 |
3 | This section contains practical examples of using reaktiv in real-world scenarios. These examples demonstrate how reactive programming can simplify complex state management challenges.
4 |
5 | ## Table of Contents
6 |
7 | - [Real-World Examples](#real-world-examples)
8 | - [Table of Contents](#table-of-contents)
9 | - [Configuration Management](#configuration-management)
10 | - [Data Processing Pipeline](#data-processing-pipeline)
11 | - [Cache Invalidation](#cache-invalidation)
12 | - [Form Validation](#form-validation)
13 | - [API Data Fetching](#api-data-fetching)
14 | - [Status Monitoring](#status-monitoring)
15 |
16 | ## Configuration Management
17 |
18 | Managing configuration from multiple sources (defaults, user settings, environment) with automatic priority resolution:
19 |
20 | ```python
21 | from reaktiv import Signal, Computed, Effect
22 |
23 | # Different configuration sources
24 | default_config = Signal({
25 | "timeout": 30,
26 | "retries": 3,
27 | "debug": False,
28 | "log_level": "INFO"
29 | })
30 |
31 | user_config = Signal({})
32 | env_config = Signal({})
33 |
34 | # Effective config merges all sources with proper priority
35 | effective_config = Computed(lambda: {
36 | **default_config(),
37 | **user_config(),
38 | **env_config() # Environment overrides everything
39 | })
40 |
41 | # Derived settings that automatically update when any config changes
42 | connection_settings = Computed(lambda: {
43 | "connect_timeout": effective_config()["timeout"],
44 | "max_attempts": effective_config()["retries"],
45 | "verbose": effective_config()["debug"]
46 | })
47 |
48 | logger_settings = Computed(lambda: {
49 | "level": effective_config()["log_level"],
50 | "debug_mode": effective_config()["debug"]
51 | })
52 |
53 | # Effect to log when settings change
54 | config_monitor = Effect(lambda: print(f"Config updated: {effective_config()}"))
55 |
56 | # Update a specific config source
57 | user_config.set({"timeout": 60, "log_level": "DEBUG"})
58 | # Automatically updates effective_config, connection_settings, logger_settings
59 | # and triggers the config_monitor effect
60 |
61 | # Later, update from environment
62 | env_config.set({"retries": 5})
63 | # Everything dependent on retries updates automatically
64 | ```
65 |
66 | ## Data Processing Pipeline
67 |
68 | Building a multi-stage data processing pipeline where each step depends on the previous one:
69 |
70 | ```python
71 | from reaktiv import Signal, Computed
72 | import json
73 |
74 | # Raw data source
75 | raw_data = Signal('{"values": [1, 2, 3, -4, 5, -6]}')
76 |
77 | # Parsing stage
78 | parsed_data = Computed(lambda: json.loads(raw_data()))
79 |
80 | # Extraction stage
81 | values = Computed(lambda: parsed_data()["values"])
82 |
83 | # Filtering stage
84 | positive_values = Computed(lambda: [x for x in values() if x > 0])
85 |
86 | # Transformation stage
87 | squared_values = Computed(lambda: [x * x for x in positive_values()])
88 |
89 | # Aggregation stage
90 | stats = Computed(lambda: {
91 | "count": len(squared_values()),
92 | "sum": sum(squared_values()),
93 | "average": sum(squared_values()) / len(squared_values()) if squared_values() else 0
94 | })
95 |
96 | print(stats())
97 | # {'count': 4, 'sum': 39, 'average': 9.75}
98 |
99 | # Update the raw data - all stages recompute automatically
100 | raw_data.set('{"values": [10, 20, 30, 40]}')
101 | print(stats())
102 | # {'count': 4, 'sum': 3000, 'average': 750.0}
103 | ```
104 |
105 | ## Cache Invalidation
106 |
107 | Smart cache invalidation system that automatically refreshes cached data when dependencies change:
108 |
109 | ```python
110 | from reaktiv import Signal, Computed, Effect
111 | import time
112 |
113 | # Simulated database
114 | db = {"user1": {"name": "Alice"}, "user2": {"name": "Bob"}}
115 |
116 | # Cache version signal - incremented when database changes
117 | cache_version = Signal(1)
118 |
119 | # Active user ID
120 | user_id = Signal("user1")
121 |
122 | # This computed value acts as our cache with automatic invalidation
123 | user_data = Computed(lambda: {
124 | "id": user_id(),
125 | "data": db[user_id()], # In real code, this would be a database query
126 | "cached_at": time.time(),
127 | "version": cache_version() # Including version causes cache refresh when version changes
128 | })
129 |
130 | # Cache monitor
131 | cache_logger = Effect(lambda: print(
132 | f"Cache data for user {user_data()['id']}: {user_data()['data']} "
133 | f"(version: {user_data()['version']})"
134 | ))
135 |
136 | # Change user - cache recomputes automatically
137 | user_id.set("user2")
138 |
139 | # Simulate database update and cache invalidation
140 | db["user2"] = {"name": "Robert"}
141 | cache_version.update(lambda v: v + 1) # Increment version to invalidate cache
142 | ```
143 |
144 | ## Form Validation
145 |
146 | Complex form validation with interdependent fields:
147 |
148 | ```python
149 | from reaktiv import Signal, Computed, Effect
150 |
151 | # Form fields
152 | username = Signal("")
153 | password = Signal("")
154 | password_confirm = Signal("")
155 | email = Signal("")
156 | terms_accepted = Signal(False)
157 |
158 | # Individual field validations
159 | username_error = Computed(lambda:
160 | "Username is required" if not username() else
161 | "Username must be at least 3 characters" if len(username()) < 3 else
162 | None
163 | )
164 |
165 | password_error = Computed(lambda:
166 | "Password is required" if not password() else
167 | "Password must be at least 8 characters" if len(password()) < 8 else
168 | None
169 | )
170 |
171 | password_match_error = Computed(lambda:
172 | "Passwords don't match" if password() != password_confirm() else None
173 | )
174 |
175 | email_error = Computed(lambda:
176 | "Email is required" if not email() else
177 | "Invalid email format" if "@" not in email() else
178 | None
179 | )
180 |
181 | terms_error = Computed(lambda:
182 | "You must accept the terms" if not terms_accepted() else None
183 | )
184 |
185 | # Combined form validation status
186 | form_errors = Computed(lambda: {
187 | "username": username_error(),
188 | "password": password_error(),
189 | "password_confirm": password_match_error(),
190 | "email": email_error(),
191 | "terms": terms_error()
192 | })
193 |
194 | has_errors = Computed(lambda: any(
195 | error is not None for error in form_errors().values()
196 | ))
197 |
198 | # Form submission state
199 | can_submit = Computed(lambda: not has_errors() and terms_accepted())
200 |
201 | # Monitor submission state
202 | submission_monitor = Effect(lambda: print(
203 | f"Form can be submitted: {can_submit()}"
204 | ))
205 |
206 | # User interaction simulation
207 | username.set("bob")
208 | email.set("bob@example.com")
209 | password.set("password123")
210 | password_confirm.set("password123")
211 | terms_accepted.set(True)
212 | ```
213 |
214 | ## API Data Fetching
215 |
216 | Coordinating API data fetching with loading states and automatic refresh:
217 |
218 | ```python
219 | import asyncio
220 | from reaktiv import Signal, Computed, Effect
221 |
222 | async def demo_api_fetching():
223 | # Signals to control the data fetch
224 | user_id = Signal(1)
225 | refresh_trigger = Signal(0) # Increment to force refresh
226 |
227 | # Loading state
228 | is_loading = Signal(False)
229 |
230 | # Error handling
231 | error = Signal(None)
232 |
233 | # Data cache
234 | user_data = Signal(None)
235 |
236 | # Combined fetch key - changes when either user_id or refresh_trigger changes
237 | fetch_key = Computed(lambda: (user_id(), refresh_trigger()))
238 |
239 | # Effect that performs the data fetching
240 | async def fetch_user_data():
241 | # Get the current fetch key (creates dependency)
242 | current_fetch_key = fetch_key()
243 | user = user_id()
244 |
245 | # Reset states
246 | error.set(None)
247 | is_loading.set(True)
248 |
249 | try:
250 | # Simulate API call
251 | await asyncio.sleep(1) # Pretend this is an API request
252 |
253 | # Simulate success or failure based on user_id
254 | if user % 2 == 0:
255 | user_data.set({"id": user, "name": f"User {user}", "status": "active"})
256 | else:
257 | # Simulate error for odd user IDs
258 | raise Exception(f"Failed to fetch user {user}")
259 |
260 | except Exception as e:
261 | error.set(str(e))
262 | user_data.set(None)
263 | finally:
264 | is_loading.set(False)
265 |
266 | # Create the effect
267 | fetcher = Effect(fetch_user_data)
268 |
269 | # Status reporting effect
270 | status_reporter = Effect(lambda: print(
271 | f"User {user_id()}: " +
272 | (f"Loading..." if is_loading() else
273 | f"Error: {error()}" if error() else
274 | f"Data: {user_data()}")
275 | ))
276 |
277 | # Let initial fetch complete
278 | await asyncio.sleep(1.5)
279 |
280 | # Change user - triggers automatic refetch
281 | print("\nSwitching to user 2...")
282 | user_id.set(2)
283 | await asyncio.sleep(1.5)
284 |
285 | # Force refresh current user
286 | print("\nRefreshing current user...")
287 | refresh_trigger.update(lambda n: n + 1)
288 | await asyncio.sleep(1.5)
289 |
290 | # Switch to user that will cause an error
291 | print("\nSwitching to user 3 (will cause error)...")
292 | user_id.set(3)
293 | await asyncio.sleep(1.5)
294 |
295 | # Run the demo
296 | # asyncio.run(demo_api_fetching())
297 | ```
298 |
299 | ## Status Monitoring
300 |
301 | Building a reactive system monitoring dashboard:
302 |
303 | ```python
304 | from reaktiv import Signal, Computed, Effect
305 |
306 | # System metrics (in a real app, these would be updated from actual monitoring)
307 | cpu_usage = Signal(25.0) # percentage
308 | memory_usage = Signal(40.0) # percentage
309 | disk_usage = Signal(60.0) # percentage
310 | error_count = Signal(0)
311 | request_count = Signal(1000)
312 |
313 | # Derived metrics
314 | error_rate = Computed(lambda:
315 | (error_count() / request_count() * 100) if request_count() > 0 else 0
316 | )
317 |
318 | # Status thresholds
319 | cpu_status = Computed(lambda:
320 | "critical" if cpu_usage() > 90 else
321 | "warning" if cpu_usage() > 70 else
322 | "normal"
323 | )
324 |
325 | memory_status = Computed(lambda:
326 | "critical" if memory_usage() > 90 else
327 | "warning" if memory_usage() > 70 else
328 | "normal"
329 | )
330 |
331 | disk_status = Computed(lambda:
332 | "critical" if disk_usage() > 90 else
333 | "warning" if disk_usage() > 80 else
334 | "normal"
335 | )
336 |
337 | error_status = Computed(lambda:
338 | "critical" if error_rate() > 5 else
339 | "warning" if error_rate() > 1 else
340 | "normal"
341 | )
342 |
343 | # Overall system status (worst of any individual status)
344 | system_status = Computed(lambda:
345 | "critical" if any(s() == "critical" for s in (cpu_status, memory_status, disk_status, error_status)) else
346 | "warning" if any(s() == "warning" for s in (cpu_status, memory_status, disk_status, error_status)) else
347 | "normal"
348 | )
349 |
350 | # Alert system
351 | def alert_system():
352 | status = system_status()
353 | components = []
354 |
355 | if cpu_status() != "normal":
356 | components.append(f"CPU: {cpu_usage():.1f}%")
357 | if memory_status() != "normal":
358 | components.append(f"Memory: {memory_usage():.1f}%")
359 | if disk_status() != "normal":
360 | components.append(f"Disk: {disk_usage():.1f}%")
361 | if error_status() != "normal":
362 | components.append(f"Error rate: {error_rate():.2f}%")
363 |
364 | if status != "normal":
365 | print(f"❗ System status: {status.upper()}")
366 | print(f" Affected components: {', '.join(components)}")
367 | else:
368 | print("✓ System status: NORMAL - All systems operational")
369 |
370 | # Monitor status changes
371 | status_monitor = Effect(alert_system)
372 |
373 | # Initial output: "✓ System status: NORMAL - All systems operational"
374 |
375 | # Simulate memory spike
376 | memory_usage.set(75.0)
377 | # Output: "❗ System status: WARNING
378 | # Affected components: Memory: 75.0%"
379 |
380 | # Simulate error increase
381 | error_count.set(100)
382 | request_count.set(1000)
383 | # Output: "❗ System status: WARNING
384 | # Affected components: Memory: 75.0%, Error rate: 10.00%"
385 |
386 | # Simulate critical CPU spike
387 | cpu_usage.set(95.0)
388 | # Output: "❗ System status: CRITICAL
389 | # Affected components: CPU: 95.0%, Memory: 75.0%, Error rate: 10.00%"
390 |
391 | # Simulate recovery
392 | memory_usage.set(50.0)
393 | cpu_usage.set(30.0)
394 | error_count.set(5)
395 | # Output: "❗ System status: WARNING
396 | # Affected components: Error rate: 0.50%"
397 |
398 | # Full recovery
399 | error_count.set(0)
400 | # Output: "✓ System status: NORMAL - All systems operational"
401 | ```
402 |
403 | Each of these examples demonstrates how reaktiv simplifies complex state management scenarios by automatically handling dependencies and updates. You can build on these patterns to create more complex reactive systems tailored to your specific needs.
404 |
405 | For more detailed examples or to contribute your own, visit our [GitHub repository](https://github.com/buiapp/reaktiv).
406 |
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/docs/index.md:
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1 | # reaktiv: Reactive Signals for Python
2 |
3 |
4 |

5 |
6 |
7 | **reaktiv** is a Python library that brings reactive programming principles to Python with first-class async support.
8 |
9 | 
10 | 
11 | 
12 | 
13 |
14 | ## Links
15 |
16 | - **Documentation**: [https://reaktiv.readthedocs.io/](https://reaktiv.readthedocs.io/)
17 | - **GitHub**: [https://github.com/buiapp/reaktiv](https://github.com/buiapp/reaktiv)
18 |
19 | ## What is reaktiv?
20 |
21 | reaktiv is a lightweight reactive state management library for Python that automatically keeps your derived values and side effects in sync with their data sources. When data changes, everything that depends on it updates automatically.
22 |
23 | Think of it as a spreadsheet for your Python application: change a cell, and all formulas using that cell recalculate instantly.
24 |
25 | ## Why Use reaktiv?
26 |
27 | reaktiv solves common pain points in state management:
28 |
29 | - **Eliminates manual state synchronization** - No more forgetting to update derived values
30 | - **Reduces bugs** - Ensures consistent state throughout your application
31 | - **Simplifies code** - Declare relationships once, not every time data changes
32 | - **Improves performance** - Only recomputes what actually needs to change
33 | - **First-class async support** - Built for Python's asyncio ecosystem
34 |
35 | [Learn more about why you should use reaktiv →](why-reaktiv.md)
36 |
37 | ## Features
38 |
39 | * **Automatic state propagation:** Change a value once, and all dependent computations update automatically
40 | * **Efficient updates:** Only the necessary parts are recomputed
41 | * **Async-friendly:** Seamlessly integrates with Python's `asyncio` for managing real-time data flows
42 | * **Zero external dependencies:** Lightweight and easy to incorporate into any project
43 | * **Type-safe:** Fully annotated for clarity and maintainability
44 |
45 | ## Overview
46 |
47 | reaktiv is built around three core primitives:
48 |
49 | 1. **Signals**: Store values and notify dependents when they change
50 | 2. **Computed Signals**: Derive values that automatically update when dependencies change
51 | 3. **Effects**: Run side effects when signals or computed signals change
52 |
53 | ```python
54 | from reaktiv import Signal, Effect
55 |
56 | # Create a signal with initial value
57 | name = Signal("Alice")
58 |
59 | # Create an effect that reacts to changes
60 | def on_name_change():
61 | print(f"Hello, {name()}!")
62 |
63 | # Create the effect
64 | greeter = Effect(on_name_change) # Prints: "Hello, Alice!"
65 |
66 | # Update the signal value
67 | name.set("Bob") # Will print: "Hello, Bob!"
68 | ```
69 |
70 | ## Documentation
71 |
72 | * [Installation](installation.md) - How to install the library
73 | * [Quick Start](quickstart.md) - Get up and running quickly
74 | * [Why reaktiv?](why-reaktiv.md) - When and why to use reaktiv
75 | * [Core Concepts](core-concepts.md) - Understanding the fundamentals
76 | * [API Reference](api/signal.md) - Detailed API documentation
77 | * [Advanced Features](advanced-features.md) - More powerful capabilities
78 | * [Real-World Examples](examples/index.md) - Practical applications
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/docs/installation.md:
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1 | # Installation
2 |
3 | ## Requirements
4 |
5 | reaktiv requires Python 3.9 or higher and has no external dependencies.
6 |
7 | ## Installing from PyPI
8 |
9 | The easiest way to install reaktiv is from PyPI using pip:
10 |
11 | ```bash
12 | pip install reaktiv
13 | ```
14 |
15 | You can also use other package managers like uv:
16 |
17 | ```bash
18 | uv pip install reaktiv
19 | ```
20 |
21 | ## Installing from Source
22 |
23 | To install the latest development version directly from the source repository:
24 |
25 | ```bash
26 | git clone https://github.com/buiapp/reaktiv.git
27 | cd reaktiv
28 | pip install -e .
29 | ```
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/docs/operators.md:
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1 | # Operators
2 |
3 | reaktiv provides several built-in operators that allow you to create new signals derived from existing ones by applying transformations or controlling the timing of emissions. These operators return a read-only signal (`_OperatorSignal`) that automatically updates based on the source signal and the operator's logic.
4 |
5 | All operators are designed to work seamlessly with both synchronous and asynchronous effects and computations.
6 |
7 | !!! note
8 | Some operators (`debounce_signal`, `throttle_signal`) rely on internal timers and therefore **require a running `asyncio` event loop** to function correctly. `filter_signal` is purely synchronous and does not have this requirement.
9 |
10 | ## `filter_signal`
11 |
12 | Creates a signal that only emits values from the source signal that satisfy a given predicate function.
13 |
14 | **Asyncio Requirement:** No
15 |
16 | **Signature:**
17 |
18 | ```python
19 | filter_signal(
20 | source: Union[Signal[T], ComputeSignal[T], _OperatorSignal[T]],
21 | predicate: Callable[[T], bool]
22 | ) -> _OperatorSignal[T]
23 | ```
24 |
25 | **Parameters:**
26 |
27 | * `source`: The input signal (`Signal`, `ComputeSignal`, or another operator signal).
28 | * `predicate`: A function that takes a value from the source signal and returns `True` if the value should be emitted, `False` otherwise.
29 |
30 | **Example:**
31 |
32 | ```python
33 | import asyncio
34 | from reaktiv import Signal, filter_signal, Effect
35 |
36 | source = Signal(0)
37 | even_numbers = filter_signal(source, lambda x: x % 2 == 0)
38 |
39 | # Effect will only run when even_numbers emits a new value
40 | # Keep a reference to the effect
41 | even_effect = Effect(lambda: print(f"Got an even number: {even_numbers()}"))
42 |
43 | source.set(1) # predicate(1) is False, even_numbers doesn't emit
44 | source.set(2) # predicate(2) is True, even_numbers emits 2
45 | # Output: Got an even number: 2
46 | source.set(3) # predicate(3) is False, even_numbers doesn't emit
47 | source.set(4) # predicate(4) is True, even_numbers emits 4
48 | # Output: Got an even number: 4
49 |
50 | # even_effect remains active until it goes out of scope or is disposed
51 | ```
52 |
53 | ## `debounce_signal`
54 |
55 | Creates a signal that emits a value from the source signal only after a specified time span has passed without the source emitting any new values. This is useful for scenarios like handling user input where you only want to react after the user has stopped typing for a moment.
56 |
57 | **Asyncio Requirement:** Yes
58 |
59 | **Signature:**
60 |
61 | ```python
62 | debounce_signal(
63 | source: Union[Signal[T], ComputeSignal[T], _OperatorSignal[T]],
64 | delay_seconds: float
65 | ) -> _OperatorSignal[T]
66 | ```
67 |
68 | **Parameters:**
69 |
70 | * `source`: The input signal.
71 | * `delay_seconds`: The time in seconds to wait for quiescence before emitting the last value received from the source.
72 |
73 | **Example:**
74 |
75 | ```python
76 | import asyncio
77 | from reaktiv import Signal, debounce_signal, Effect
78 |
79 | async def main():
80 | query = Signal("")
81 | # Only process the query 500ms after the user stops typing
82 | debounced_query = debounce_signal(query, 0.5)
83 |
84 | # Keep a reference to the effect
85 | query_effect = Effect(lambda: print(f"Processing search for: {debounced_query()}"))
86 |
87 | print("User types 're'...")
88 | query.set("re")
89 | await asyncio.sleep(0.2)
90 | print("User types 'aktiv'...")
91 | query.set("reaktiv") # Timer resets
92 | await asyncio.sleep(0.2)
93 | print("User types '!'...")
94 | query.set("reaktiv!") # Timer resets again
95 |
96 | print("Waiting for debounce...")
97 | await asyncio.sleep(0.6) # Wait longer than the debounce delay
98 | # Output: Processing search for: reaktiv!
99 |
100 | # query_effect remains active
101 |
102 | asyncio.run(main())
103 | ```
104 |
105 | ## `throttle_signal`
106 |
107 | Creates a signal that emits a value from the source signal immediately (if `leading` is `True`), then ignores subsequent source emissions for a specified time interval. It can optionally emit the last value received during the ignored interval when the interval ends (if `trailing` is `True`). This is useful for rate-limiting events, like handling rapid button clicks or frequent sensor updates.
108 |
109 | **Asyncio Requirement:** Yes
110 |
111 | **Signature:**
112 |
113 | ```python
114 | throttle_signal(
115 | source: Union[Signal[T], ComputeSignal[T], _OperatorSignal[T]],
116 | interval_seconds: float,
117 | leading: bool = True,
118 | trailing: bool = False
119 | ) -> _OperatorSignal[T]
120 | ```
121 |
122 | **Parameters:**
123 |
124 | * `source`: The input signal.
125 | * `interval_seconds`: The duration in seconds during which source emissions are ignored after an emission.
126 | * `leading`: If `True` (default), emit the first value immediately when it arrives.
127 | * `trailing`: If `True` (default is `False`), emit the last value received during the throttle interval after the interval has passed.
128 |
129 | **Example (Leading only):**
130 |
131 | ```python
132 | import asyncio
133 | from reaktiv import Signal, throttle_signal, Effect
134 |
135 | async def main():
136 | clicks = Signal(0)
137 | # Handle click, but ignore rapid clicks within 200ms
138 | throttled_clicks = throttle_signal(clicks, 0.2, leading=True, trailing=False)
139 |
140 | # Keep a reference to the effect
141 | click_effect = Effect(lambda: print(f"Click handled! Count: {throttled_clicks()}"))
142 |
143 | print("Rapid clicks...")
144 | clicks.set(1) # Emitted (leading)
145 | # Output: Click handled! Count: 1
146 | await asyncio.sleep(0.05)
147 | clicks.set(2) # Throttled
148 | await asyncio.sleep(0.05)
149 | clicks.set(3) # Throttled
150 |
151 | print("Waiting past interval...")
152 | await asyncio.sleep(0.2) # Interval ends
153 |
154 | print("Another click...")
155 | clicks.set(4) # Emitted (leading, interval passed)
156 | # Output: Click handled! Count: 4
157 |
158 | await asyncio.sleep(0.1)
159 | # click_effect remains active
160 |
161 | asyncio.run(main())
162 | ```
163 |
164 | **Example (Leading and Trailing):**
165 |
166 | ```python
167 | import asyncio
168 | from reaktiv import Signal, throttle_signal, Effect
169 |
170 | async def main():
171 | sensor = Signal(0.0)
172 | # Process sensor value immediately, and also the last value after 1s interval
173 | processed_sensor = throttle_signal(sensor, 1.0, leading=True, trailing=True)
174 |
175 | # Keep a reference to the effect
176 | sensor_effect = Effect(lambda: print(f"Processed sensor value: {processed_sensor():.2f}"))
177 |
178 | print("Sensor updates rapidly...")
179 | sensor.set(10.5) # Emitted (leading)
180 | # Output: Processed sensor value: 10.50
181 | await asyncio.sleep(0.3)
182 | sensor.set(11.2)
183 | await asyncio.sleep(0.3)
184 | sensor.set(12.8) # Last value in interval
185 |
186 | print("Waiting for trailing edge...")
187 | await asyncio.sleep(0.5) # 1.1s total elapsed, interval ended
188 | # Output: Processed sensor value: 12.80 (trailing)
189 |
190 | await asyncio.sleep(0.1)
191 | # sensor_effect remains active
192 |
193 | asyncio.run(main())
194 | ```
195 |
196 | ## `pairwise_signal`
197 |
198 | Creates a signal that emits tuples containing the previous and current values from a source signal. This is useful for tracking how values change over time and comparing current values with previous ones.
199 |
200 | **Asyncio Requirement:** No
201 |
202 | **Signature:**
203 |
204 | ```python
205 | pairwise_signal(
206 | source: Union[Signal[T], ComputeSignal[T], _OperatorSignal[T]],
207 | emit_on_first: bool = False
208 | ) -> _OperatorSignal[Optional[Tuple[Optional[T], T]]]
209 | ```
210 |
211 | **Parameters:**
212 |
213 | * `source`: The input signal.
214 | * `emit_on_first`: If `True`, emits `(None, first_value)` when the source emits its first value. If `False` (default), the first emission from the source does not produce an output, and the second emission produces `(first_value, second_value)`.
215 |
216 | **Example (Default behavior - skip first):**
217 |
218 | ```python
219 | import asyncio
220 | from reaktiv import Signal, pairwise_signal, Effect
221 |
222 | async def main():
223 | counter = Signal(0)
224 | # Create a signal that emits (previous, current) tuples
225 | changes = pairwise_signal(counter)
226 |
227 | # Keep a reference to the effect
228 | change_effect = Effect(lambda: print(f"Counter changed from {changes()[0]} to {changes()[1]}"))
229 |
230 | # Initial value doesn't emit with default settings (emit_on_first=False)
231 | print("Initial state - no effect output yet")
232 |
233 | # First change
234 | counter.set(1)
235 | # Output: Counter changed from 0 to 1
236 |
237 | # Second change
238 | counter.set(5)
239 | # Output: Counter changed from 1 to 5
240 |
241 | # When value doesn't change, no emission occurs
242 | counter.set(5) # No output
243 |
244 | # Third change
245 | counter.set(10)
246 | # Output: Counter changed from 5 to 10
247 |
248 | await asyncio.sleep(0.1)
249 | # change_effect remains active
250 |
251 | asyncio.run(main())
252 | ```
253 |
254 | **Example (Emit on first value):**
255 |
256 | ```python
257 | import asyncio
258 | from reaktiv import Signal, pairwise_signal, Effect
259 |
260 | async def main():
261 | price = Signal(100.0)
262 | # Create a signal that emits (previous, current) tuples, including on first value
263 | price_changes = pairwise_signal(price, emit_on_first=True)
264 |
265 | # Keep a reference to the effect
266 | # Handle the initial case where previous might be None
267 | price_effect = Effect(lambda: process_price_change(price_changes()))
268 |
269 | def process_price_change(change_tuple):
270 | prev, curr = change_tuple
271 | if prev is None:
272 | print(f"Initial price: ${curr:.2f}")
273 | else:
274 | diff = curr - prev
275 | percent = (diff / prev) * 100 if prev != 0 else 0
276 | direction = "up" if diff > 0 else "down" if diff < 0 else "unchanged"
277 | print(f"Price {direction}: ${curr:.2f} (${diff:+.2f}, {percent:+.1f}%)")
278 |
279 | # With emit_on_first=True, this produces output for the initial value
280 | # Output: Initial price: $100.00
281 |
282 | # First change
283 | price.set(105.0)
284 | # Output: Price up: $105.00 (+$5.00, +5.0%)
285 |
286 | # Second change
287 | price.set(95.5)
288 | # Output: Price down: $95.50 (-$9.50, -9.0%)
289 |
290 | await asyncio.sleep(0.1)
291 | # price_effect remains active
292 |
293 | asyncio.run(main())
294 | ```
295 |
296 | **Use Cases:**
297 |
298 | * Calculating the difference between consecutive values
299 | * Detecting direction of change (increasing/decreasing)
300 | * Tracking value transitions for state machines
301 | * Computing derivatives or rates of change
302 | * Building charts and visualizations with transition animations
303 |
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/docs/quickstart.md:
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1 | # Quick Start Guide
2 |
3 | This guide will walk you through the basic usage of reaktiv to help you get started with reactive programming in Python.
4 |
5 | ## Basic Concepts
6 |
7 | reaktiv is built around three core primitives:
8 |
9 | 1. **Signals**: Store a value and notify dependents when it changes
10 | 2. **Computed Signals**: Derive values that automatically update when dependencies change
11 | 3. **Effects**: Run side effects when signals or computed signals change
12 |
13 | ## Installation
14 |
15 | The quickest way to get started is to install reaktiv using pip:
16 |
17 | ```bash
18 | pip install reaktiv
19 | # or with uv
20 | uv pip install reaktiv
21 | ```
22 |
23 | ## Basic Example
24 |
25 | Here's a simple example showing the core functionality:
26 |
27 | ```python
28 | import asyncio
29 | from reaktiv import Signal, Effect
30 |
31 | async def main():
32 | # Create a signal with initial value
33 | name = Signal("Alice")
34 |
35 | # Create an effect that depends on the signal
36 | async def greet():
37 | print(f"Hello, {name()}!")
38 |
39 | # Create and schedule the effect (important: keep a reference to prevent garbage collection)
40 | greeter = Effect(greet)
41 |
42 | # Prints: "Hello, Alice!"
43 |
44 | # Update the signal value
45 | name.set("Bob") # Will trigger the effect to run again
46 |
47 | # Give the effect time to process
48 | await asyncio.sleep(0) # Prints: "Hello, Bob!"
49 |
50 | asyncio.run(main())
51 | ```
52 |
53 | ## Solving Real Problems
54 |
55 | Let's look at a more practical example. Imagine you're calculating the total price of items in a shopping cart:
56 |
57 | ```python
58 | from reaktiv import Signal, Computed, Effect
59 |
60 | # Create signals for our base values
61 | price = Signal(10.0)
62 | quantity = Signal(2)
63 | tax_rate = Signal(0.1) # 10% tax
64 |
65 | # Create computed values that automatically update when dependencies change
66 | subtotal = Computed(lambda: price() * quantity())
67 | tax = Computed(lambda: subtotal() * tax_rate())
68 | total = Computed(lambda: subtotal() + tax())
69 |
70 | # Create an effect to display the total (will run initially and when dependencies change)
71 | display = Effect(lambda: print(f"Order total: ${total():.2f}"))
72 | # Prints: "Order total: $22.00"
73 |
74 | # Update a signal - all dependent computed values and effects update automatically
75 | quantity.set(3)
76 | # Prints: "Order total: $33.00"
77 |
78 | # Update multiple values
79 | price.set(15.0)
80 | tax_rate.set(0.15)
81 | # Prints: "Order total: $51.75"
82 | ```
83 |
84 | Notice how we never needed to manually recalculate the total! reaktiv automatically detects the dependencies between values and updates them when needed.
85 |
86 | ## Computed Values
87 |
88 | Computed signals let you derive values from other signals:
89 |
90 | ```python
91 | from reaktiv import Signal, Computed
92 |
93 | # Create base signals
94 | price = Signal(100)
95 | tax_rate = Signal(0.2)
96 |
97 | # Create a computed signal that depends on price and tax_rate
98 | total = Computed(lambda: price() * (1 + tax_rate()))
99 |
100 | print(total()) # 120.0
101 |
102 | # Change a dependency
103 | tax_rate.set(0.25)
104 |
105 | # The computed value updates automatically
106 | print(total()) # 125.0
107 | ```
108 |
109 | ## Working with Updates
110 |
111 | Instead of using `set(new_value)`, you can use `update()` to modify a signal based on its current value:
112 |
113 | ```python
114 | from reaktiv import Signal
115 |
116 | counter = Signal(0)
117 |
118 | # Standard way
119 | counter.set(counter() + 1)
120 |
121 | # Using update() for cleaner syntax
122 | counter.update(lambda x: x + 1)
123 |
124 | print(counter()) # 2
125 | ```
126 |
127 | ## Batching Updates
128 |
129 | When making multiple signal updates, you can batch them together to optimize performance:
130 |
131 | ```python
132 | from reaktiv import Signal, Computed, batch
133 |
134 | x = Signal(10)
135 | y = Signal(20)
136 | sum_xy = Computed(lambda: x() + y())
137 |
138 | # Without batching, computed values are recalculated after each signal update
139 | x.set(5) # Recalculates sum_xy
140 | y.set(10) # Recalculates sum_xy again
141 |
142 | # With batching, computed values are recalculated only once after all updates
143 | with batch():
144 | x.set(15) # No recalculation yet
145 | y.set(25) # No recalculation yet
146 | # sum_xy will be recalculated only once after the batch completes
147 | ```
148 |
149 | ## Custom Equality
150 |
151 | By default, signals use identity (`is`) for equality checking. You can provide a custom equality function:
152 |
153 | ```python
154 | from reaktiv import Signal
155 |
156 | # Custom equality function for case-insensitive string comparison
157 | def case_insensitive_equal(a, b):
158 | return a.lower() == b.lower()
159 |
160 | # Create a signal with custom equality function
161 | name = Signal("Alice", equal=case_insensitive_equal)
162 |
163 | # This won't trigger updates because "alice" is considered equal to "Alice"
164 | name.set("alice")
165 |
166 | # This will trigger updates because "Bob" is not equal to "Alice"
167 | name.set("Bob")
168 | ```
169 |
170 | ## Asynchronous Effects
171 |
172 | reaktiv has first-class support for async functions:
173 |
174 | ```python
175 | import asyncio
176 | from reaktiv import Signal, Effect
177 |
178 | async def main():
179 | counter = Signal(0)
180 |
181 | async def print_counter():
182 | print(f"Counter value is: {counter()}")
183 |
184 | # Keep a reference to prevent garbage collection
185 | counter_effect = Effect(print_counter)
186 |
187 | for i in range(1, 4):
188 | await asyncio.sleep(1)
189 | counter.set(i)
190 |
191 | # Cleaning up when done
192 | counter_effect.dispose()
193 |
194 | asyncio.run(main())
195 | ```
196 |
197 | ## Next Steps
198 |
199 | - Read [Why reaktiv?](why-reaktiv.md) to understand when and why to use reaktiv
200 | - See the [Core Concepts](core-concepts.md) page for a deeper understanding of reaktiv's design
201 | - Check out the [Examples](examples/index.md) page for real-world usage examples
202 | - Explore the [Advanced Features](advanced-features.md) for more powerful capabilities
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/docs/requirements.txt:
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1 | mkdocs>=1.4.0
2 | mkdocs-material>=9.1.0
3 | mkdocstrings>=0.22.0
4 | mkdocstrings-python>=1.1.0
5 | pymdown-extensions>=10.0.0
6 | # Add specific version for mermaid support
7 | mkdocs-mermaid2-plugin>=0.6.0
8 |
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/docs/why-reaktiv.md:
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1 | # Why reaktiv?
2 |
3 | When building applications that manage state, developers often struggle with keeping derived data in sync with its sources. reaktiv solves this fundamental problem through automatic dependency tracking and fine-grained reactivity.
4 |
5 | ## The Hidden Cost You Didn't Know You Were Paying
6 |
7 | Many developers don't realize they're already paying a cost when managing state manually:
8 |
9 | 1. **Mental Overhead**: Constantly tracking what needs to update when something changes
10 | 2. **Bug Potential**: Forgotten updates leading to inconsistent state
11 | 3. **Refactoring Risk**: Adding new derived state requires updating many places
12 | 4. **Testing Complexity**: More moving parts to test when state updates are manual
13 |
14 | reaktiv eliminates these hidden costs, allowing you to:
15 |
16 | - Declare relationships once
17 | - Let the system handle updates automatically
18 | - Focus on business logic rather than state synchronization
19 | - Build more reliable and maintainable applications
20 |
21 | Reactive programming isn't just another tool—it's a fundamental shift in how we think about state management that can dramatically simplify complex applications.
22 |
23 | ## The Pain Points reaktiv Solves
24 |
25 | ### 1. The Manual State Synchronization Problem
26 |
27 | Without a reactive system, developers typically face these challenges:
28 |
29 | #### Before reaktiv: Manual State Propagation
30 |
31 | ```python
32 | # Traditional approach with manual propagation
33 | user_name = "Alice"
34 | user_age = 30
35 | # Derived state that depends on the above values
36 | greeting = f"Hello, {user_name}! You are {user_age} years old."
37 |
38 | # When state changes, you must remember to update ALL derived values
39 | user_name = "Bob" # State changed!
40 | # Oops! Forgot to update greeting
41 | # greeting still shows "Hello, Alice! You are 30 years old."
42 |
43 | # Later in the code...
44 | greeting = f"Hello, {user_name}! You are {user_age} years old." # Manual update
45 | ```
46 |
47 | #### After reaktiv: Automatic Propagation
48 |
49 | ```python
50 | from reaktiv import Signal, Computed
51 |
52 | # State as signals
53 | user_name = Signal("Alice")
54 | user_age = Signal(30)
55 |
56 | # Derived state automatically updates when dependencies change
57 | greeting = Computed(lambda: f"Hello, {user_name()}! You are {user_age()} years old.")
58 |
59 | print(greeting()) # "Hello, Alice! You are 30 years old."
60 |
61 | # When state changes, derived values update automatically
62 | user_name.set("Bob")
63 | print(greeting()) # "Hello, Bob! You are 30 years old."
64 | ```
65 |
66 | ### 2. The "Hidden State" Problem
67 |
68 | Many developers don't realize how much "hidden state" exists in their applications. Every time you compute a value based on other values, you're creating state that needs to be managed.
69 |
70 | ```python
71 | # Without reaktiv: Hidden state management
72 | def get_total_price(items, tax_rate):
73 | subtotal = sum(item["price"] for item in items)
74 | return subtotal * (1 + tax_rate)
75 |
76 | # This function is called in many places
77 | # If items or tax_rate changes, you need to manually recalculate everywhere
78 | ```
79 |
80 | #### After reaktiv: Making Hidden State Explicit
81 |
82 | ```python
83 | from reaktiv import Signal, Computed
84 |
85 | # Make state explicit with signals
86 | items = Signal([])
87 | tax_rate = Signal(0.1)
88 |
89 | # Hidden state becomes explicit computed values
90 | subtotal = Computed(lambda: sum(item["price"] for item in items()))
91 | total_price = Computed(lambda: subtotal() * (1 + tax_rate()))
92 |
93 | # Now when items or tax_rate changes, total_price updates automatically
94 | items.set([{"price": 10}, {"price": 20}])
95 | print(total_price()) # 33.0
96 |
97 | tax_rate.set(0.2)
98 | print(total_price()) # 36.0 - automatically recalculated
99 | ```
100 |
101 | ### 3. The Dependency Tracking Problem
102 |
103 | Manually tracking which parts of your code depend on which data becomes increasingly complex as applications grow.
104 |
105 | ```python
106 | # Traditional approach with manual tracking
107 | class ShoppingCart:
108 | def __init__(self, items=None):
109 | self.items = items or []
110 | self.subtotal = self._calculate_subtotal()
111 | self.tax = self._calculate_tax()
112 | self.total = self.subtotal + self.tax
113 |
114 | def _calculate_subtotal(self):
115 | return sum(item.price for item in self.items)
116 |
117 | def _calculate_tax(self):
118 | return self.subtotal * 0.1 # 10% tax
119 |
120 | def add_item(self, item):
121 | self.items.append(item)
122 | # Now we must manually update everything that depends on items
123 | self.subtotal = self._calculate_subtotal()
124 | self.tax = self._calculate_tax() # Depends on subtotal
125 | self.total = self.subtotal + self.tax # Depends on both
126 |
127 | # What if we add more derived values? The dependency chain gets complex!
128 | ```
129 |
130 | #### After reaktiv: Automatic Dependency Tracking
131 |
132 | ```python
133 | from reaktiv import Signal, Computed
134 |
135 | class ReactiveShoppingCart:
136 | def __init__(self, initial_items=None):
137 | self.items = Signal(initial_items or [])
138 |
139 | # Dependencies are automatically tracked
140 | self.subtotal = Computed(lambda: sum(item.price for item in self.items()))
141 | self.tax = Computed(lambda: self.subtotal() * 0.1) # Automatically depends on subtotal
142 | self.total = Computed(lambda: self.subtotal() + self.tax()) # Automatically depends on both
143 |
144 | # Adding more derived values is easy and doesn't increase complexity
145 | self.discount = Computed(lambda: 0.05 if self.subtotal() > 100 else 0)
146 | self.final_price = Computed(lambda: self.total() * (1 - self.discount()))
147 |
148 | def add_item(self, item):
149 | # Just update the source data
150 | self.items.update(lambda items: items + [item])
151 | # No need to manually update dependencies - they update automatically!
152 |
153 | cart = ReactiveShoppingCart()
154 | ```
155 |
156 | ## Before & After: How reaktiv Makes Your Code Better
157 |
158 | ### Example 1: Configuration with Overrides
159 |
160 | #### Before reaktiv:
161 |
162 | ```python
163 | def load_config():
164 | default_config = {"timeout": 30, "retries": 3, "debug": False}
165 | try:
166 | with open("user_config.json") as f:
167 | user_config = json.load(f)
168 | except FileNotFoundError:
169 | user_config = {}
170 |
171 | # Merge configs
172 | config = {**default_config, **user_config}
173 |
174 | # Derived values
175 | connection_settings = {
176 | "connect_timeout": config["timeout"],
177 | "max_attempts": config["retries"],
178 | "verbose": config["debug"],
179 | }
180 |
181 | return config, connection_settings
182 |
183 | # Now what happens when config changes at runtime?
184 | # You need to reload everything and update all dependents manually!
185 | ```
186 |
187 | #### After reaktiv:
188 |
189 | ```python
190 | from reaktiv import Signal, Computed
191 |
192 | default_config = Signal({"timeout": 30, "retries": 3, "debug": False})
193 | user_config = Signal({})
194 |
195 | # Derived values automatically stay in sync
196 | effective_config = Computed(lambda: {**default_config(), **user_config()})
197 |
198 | connection_settings = Computed(lambda: {
199 | "connect_timeout": effective_config()["timeout"],
200 | "max_attempts": effective_config()["retries"],
201 | "verbose": effective_config()["debug"],
202 | })
203 |
204 | # When config changes, everything updates automatically
205 | user_config.set({"timeout": 60})
206 | print(connection_settings()) # connect_timeout is now 60
207 | ```
208 |
209 | ### Example 2: Data Processing Pipeline
210 |
211 | #### Before reaktiv:
212 |
213 | ```python
214 | class DataProcessor:
215 | def __init__(self, raw_data):
216 | self.raw_data = raw_data
217 | self.filtered_data = self._filter_data()
218 | self.transformed_data = self._transform_data()
219 | self.summary = self._summarize()
220 |
221 | def _filter_data(self):
222 | return [x for x in self.raw_data if x > 0]
223 |
224 | def _transform_data(self):
225 | return [x * 2 for x in self.filtered_data]
226 |
227 | def _summarize(self):
228 | return {
229 | "count": len(self.transformed_data),
230 | "sum": sum(self.transformed_data),
231 | "avg": sum(self.transformed_data) / len(self.transformed_data) if self.transformed_data else 0
232 | }
233 |
234 | def update_data(self, new_data):
235 | self.raw_data = new_data
236 | # Must manually update every step in the chain
237 | self.filtered_data = self._filter_data()
238 | self.transformed_data = self._transform_data()
239 | self.summary = self._summarize()
240 | ```
241 |
242 | #### After reaktiv:
243 |
244 | ```python
245 | from reaktiv import Signal, Computed
246 |
247 | class ReactiveDataProcessor:
248 | def __init__(self, initial_data):
249 | self.raw_data = Signal(initial_data)
250 |
251 | # Each step automatically updates when dependencies change
252 | self.filtered_data = Computed(lambda: [x for x in self.raw_data() if x > 0])
253 | self.transformed_data = Computed(lambda: [x * 2 for x in self.filtered_data()])
254 | self.summary = Computed(lambda: {
255 | "count": len(self.transformed_data()),
256 | "sum": sum(self.transformed_data()),
257 | "avg": sum(self.transformed_data()) / len(self.transformed_data()) if self.transformed_data() else 0
258 | })
259 |
260 | def update_data(self, new_data):
261 | # Just update the source data - everything else updates automatically
262 | self.raw_data.set(new_data)
263 |
264 | # Usage
265 | processor = ReactiveDataProcessor([1, -2, 3, -4, 5])
266 | print(processor.summary()) # Computed from the chain
267 | processor.update_data([10, 20, 30]) # Everything recalculates automatically
268 | ```
269 |
270 | ## Comparing reaktiv with Alternatives
271 |
272 | ### reaktiv vs. RxPy/ReactiveX
273 |
274 | | Feature | reaktiv | RxPy |
275 | |---------|---------|------|
276 | | **Focus** | Fine-grained state management | Event streams and operations |
277 | | **Conceptual Model** | Signal-based (value over time) | Observable streams (collections over time) |
278 | | **Learning Curve** | Gentle, minimal API | Steeper, many operators to learn |
279 | | **Async Integration** | First-class Python `asyncio` support | Separate scheduler system |
280 | | **Dependencies** | Zero external dependencies | Has external dependencies |
281 | | **Granularity** | Value-level reactivity | Stream-level operations |
282 | | **Execution Model** | Pull-based (lazy) | Push-based (eager) |
283 |
284 | ### reaktiv vs. Manual Observer Pattern
285 |
286 | | Feature | reaktiv | Manual Observer Pattern |
287 | |---------|---------|-------------------------|
288 | | **Dependency Tracking** | Automatic | Manual |
289 | | **Granularity** | Fine-grained | Coarse-grained |
290 | | **Boilerplate** | Minimal | Extensive |
291 | | **Memoization** | Built-in | Manual |
292 | | **Memory Management** | Automatic cleanup | Manual cleanup |
293 |
294 | ## When to Use reaktiv
295 |
296 | reaktiv shines in these scenarios:
297 |
298 | 1. **Complex State Dependencies**: When you have multiple pieces of state that depend on each other
299 | 2. **Derived Data**: When you compute values based on other values that change over time
300 | 3. **Reactive UIs**: When UI components need to update in response to state changes
301 | 4. **Data Processing Pipelines**: When you transform data through multiple steps
302 | 5. **Configuration Management**: When you need to compute effective configurations from multiple sources
303 | 6. **Caching Systems**: For smart cache invalidation when dependencies change
304 |
305 | ## When Not to Use reaktiv
306 |
307 | reaktiv might not be the best fit for:
308 |
309 | 1. **Simple State**: If your application state is very simple with few dependencies
310 | 2. **Fire-and-forget Events**: For pure event handling without state tracking, a simpler event system may suffice
311 | 3. **Stream Processing**: If you're primarily doing stream operations like filtering, mapping large data streams (consider RxPy)
312 | 4. **Performance-critical, High-frequency Updates**: For systems where absolute minimal overhead is critical
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/examples/fastapi_websocket.py:
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1 | """
2 | FastAPI WebSocket example with reaktiv.
3 |
4 | This example shows how to use reaktiv with FastAPI to create a reactive
5 | websocket that automatically reflects state changes.
6 |
7 | To run this example:
8 | pip install fastapi uvicorn websockets
9 |
10 | # Run directly with uvicorn:
11 | uvicorn examples.fastapi_websocket:app --reload
12 |
13 | # Or if using uv:
14 | uv run uvicorn examples.fastapi_websocket:app --reload
15 |
16 | # NOT like this:
17 | # uv run python uvicorn examples.fastapi_websocket:app --reload
18 |
19 | Then:
20 | - Connect to the WebSocket at ws://localhost:8000/ws
21 | - Use the REST endpoints to modify the state
22 | - Watch the WebSocket update in real-time
23 | """
24 | import asyncio
25 | import json
26 | from typing import Dict, List, Set
27 | from contextlib import asynccontextmanager
28 |
29 | import uvicorn
30 | from fastapi import FastAPI, WebSocket, WebSocketDisconnect
31 | from fastapi.responses import HTMLResponse
32 |
33 | from reaktiv import Signal, Computed, Effect
34 |
35 | # Create a lifespan context manager
36 | @asynccontextmanager
37 | async def lifespan(app: FastAPI):
38 | # Setup code - runs before the application starts receiving requests
39 | print("Starting up: Setting up reactive effects...")
40 | manager.setup_effect()
41 |
42 | yield # This is where FastAPI serves requests
43 |
44 | # Cleanup code - runs when the application is shutting down
45 | print("Shutting down: Cleaning up resources...")
46 |
47 | # Initialize FastAPI app with lifespan
48 | app = FastAPI(
49 | title="Reaktiv FastAPI WebSocket Example",
50 | lifespan=lifespan
51 | )
52 |
53 | # State management with Reaktiv
54 | counter = Signal(0)
55 | messages = Signal([])
56 | active_users = Signal(0)
57 |
58 | # Computed values
59 | state = Computed(lambda: {
60 | "counter": counter(),
61 | "messages": messages(),
62 | "active_users": active_users(),
63 | "last_message": messages()[-1] if messages() else None
64 | })
65 |
66 | # WebSocket connection manager
67 | class ConnectionManager:
68 | def __init__(self):
69 | self.active_connections: Set[WebSocket] = set()
70 | self._broadcast_effect = None # Don't create Effect at import time
71 |
72 | def setup_effect(self):
73 | """Create the Effect when we're in an asyncio context"""
74 | if self._broadcast_effect is None:
75 | self._broadcast_effect = Effect(self._broadcast_state)
76 |
77 | async def connect(self, websocket: WebSocket):
78 | # Create the Effect when we have a websocket connection (inside asyncio context)
79 | self.setup_effect()
80 |
81 | await websocket.accept()
82 | self.active_connections.add(websocket)
83 | active_users.set(len(self.active_connections))
84 |
85 | # Send initial state
86 | await self._send_state(websocket)
87 |
88 | def disconnect(self, websocket: WebSocket):
89 | self.active_connections.remove(websocket)
90 | active_users.set(len(self.active_connections))
91 |
92 | async def _broadcast_state(self):
93 | """Effect that broadcasts state when it changes"""
94 | current_state = state()
95 | if self.active_connections:
96 | data = json.dumps(current_state)
97 | # Create tasks for each connection to avoid blocking
98 | await asyncio.gather(
99 | *[ws.send_text(data) for ws in self.active_connections],
100 | return_exceptions=True
101 | )
102 |
103 | async def _send_state(self, websocket: WebSocket):
104 | """Send current state to a specific client"""
105 | current_state = state()
106 | await websocket.send_text(json.dumps(current_state))
107 |
108 | manager = ConnectionManager()
109 |
110 | # HTML for a simple test client
111 | html = """
112 |
113 |
114 |
115 | Reaktiv WebSocket Demo
116 |
122 |
123 |
124 | Reaktiv WebSocket Demo
125 |
126 |
127 |
Control Panel
128 |
129 |
130 |
131 |
132 |
133 |
134 |
135 |
136 |
137 |
138 |
176 |
177 |
178 | """
179 |
180 | @app.get("/")
181 | async def get():
182 | """Serve a simple HTML client for testing"""
183 | return HTMLResponse(html)
184 |
185 | @app.websocket("/ws")
186 | async def websocket_endpoint(websocket: WebSocket):
187 | """WebSocket endpoint that reflects reaktiv state"""
188 | await manager.connect(websocket)
189 | try:
190 | while True:
191 | # Just keep the connection open
192 | await websocket.receive_text()
193 | except WebSocketDisconnect:
194 | manager.disconnect(websocket)
195 |
196 | @app.get("/increment")
197 | async def increment():
198 | """Increment the counter"""
199 | counter.update(lambda c: c + 1)
200 | return {"status": "incremented", "value": counter()}
201 |
202 | @app.get("/decrement")
203 | async def decrement():
204 | """Decrement the counter"""
205 | counter.update(lambda c: c - 1)
206 | return {"status": "decremented", "value": counter()}
207 |
208 | @app.get("/reset")
209 | async def reset():
210 | """Reset the counter to zero"""
211 | counter.set(0)
212 | return {"status": "reset", "value": counter()}
213 |
214 | @app.post("/message")
215 | async def add_message(message: Dict[str, str]):
216 | """Add a message to the list"""
217 | text = message.get("text", "").strip()
218 | if text:
219 | messages.update(lambda msgs: msgs + [text])
220 | return {"status": "message added"}
221 |
222 | if __name__ == "__main__":
223 | # Make sure app runs with appropriate host and port
224 | print("Starting the FastAPI app with uvicorn...")
225 | print("Access the demo at http://localhost:8000")
226 | uvicorn.run(app, host="0.0.0.0", port=8000)
227 |
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/examples/iot_sensor_agent_thread.py:
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1 | """
2 | IoT Sensor Agent with reaktiv.
3 |
4 | This example demonstrates how reaktiv can be used to create a reactive system
5 | that responds to hardware sensor changes running in a separate thread.
6 |
7 | Key concepts demonstrated:
8 | - Thread-safe reactivity with hardware sensors
9 | - Automatic recalculation of derived values as sensor readings change
10 | - Reactive effects for monitoring, alerting, and taking action on sensor data
11 | - Clean separation between sensor data acquisition and business logic
12 |
13 | In a real-world application:
14 | - The sensor loop would interface with actual hardware via libraries like
15 | RPi.GPIO, Adafruit_CircuitPython, Arduino libraries, etc.
16 | - Multiple effects might update displays, trigger actuators, log to databases,
17 | or send notifications through various channels
18 | """
19 | import threading
20 | import time
21 | import random
22 | from reaktiv import Signal, Computed, Effect, batch
23 |
24 | class IoTSensorAgent:
25 | """Threaded IoT sensor agent that provides reactive sensor data updates."""
26 |
27 | def __init__(self):
28 | # Core sensor signals - in a real system these would be updated from hardware
29 | self.temperature = Signal(21.0)
30 | self.humidity = Signal(50.0)
31 | self.is_running = Signal(False)
32 | self.sensor_error = Signal(False)
33 |
34 | # Computed values automatically derive from raw sensor data
35 | self.heat_index = Computed(lambda: self.temperature() + 0.05 * self.humidity())
36 | self.comfort_level = Computed(self._calculate_comfort_level)
37 | self.sensor_status = Computed(lambda:
38 | "ERROR" if self.sensor_error() else
39 | "ACTIVE" if self.is_running() else "STANDBY"
40 | )
41 |
42 | self._thread = None
43 |
44 | def _calculate_comfort_level(self) -> str:
45 | """Determine comfort level based on temperature and humidity."""
46 | t, h = self.temperature(), self.humidity()
47 |
48 | if t < 18: return "TOO COLD"
49 | if t > 26: return "TOO HOT"
50 | if h < 30: return "TOO DRY"
51 | if h > 70: return "TOO HUMID"
52 | return "COMFORTABLE"
53 |
54 | def start_sensor(self):
55 | """Start the sensor agent thread."""
56 | if self.is_running():
57 | return
58 |
59 | self.is_running.set(True)
60 | self._thread = threading.Thread(target=self._sensor_loop, daemon=True)
61 | self._thread.start()
62 | print(f"Sensor agent started with status: {self.sensor_status()}")
63 |
64 | def stop_sensor(self):
65 | """Stop the sensor agent."""
66 | self.is_running.set(False)
67 | if self._thread:
68 | self._thread.join(timeout=1.0)
69 | self._thread = None
70 |
71 | def _sensor_loop(self):
72 | """Main sensor polling loop running in a separate thread.
73 |
74 | In a real application, this would read from actual hardware sensors.
75 | """
76 | try:
77 | while self.is_running():
78 | # Simulate sensor readings with small random changes
79 | # In a real application: read from I2C/SPI/GPIO sensors here
80 | new_temp = max(10, min(35, self.temperature() + random.uniform(-0.5, 0.5)))
81 | new_humidity = max(20, min(90, self.humidity() + random.uniform(-1, 1)))
82 |
83 | # Occasionally simulate sensor error (1% chance)
84 | # In a real application: detect actual hardware communication errors
85 | if random.random() < 0.01:
86 | self.sensor_error.set(True)
87 | time.sleep(2)
88 | self.sensor_error.set(False)
89 |
90 | # Update signals if not in error state
91 | if not self.sensor_error():
92 | # Simply updating these signals will automatically trigger
93 | # all dependent computed values and effects
94 | with batch():
95 | self.temperature.set(new_temp)
96 | self.humidity.set(new_humidity)
97 |
98 | time.sleep(1)
99 |
100 | except Exception as e:
101 | print(f"Sensor error: {e}")
102 | with batch():
103 | self.sensor_error.set(True)
104 | self.is_running.set(False)
105 |
106 |
107 | def demo():
108 | """Demonstrate how reaktiv enables automatic reactions to sensor data changes."""
109 | # Create sensor agent
110 | sensor = IoTSensorAgent()
111 |
112 | # Define effect functions
113 | def log_sensor():
114 | """Log current sensor readings to console."""
115 | print(
116 | f"Temp: {sensor.temperature():.1f}°C | "
117 | f"Humidity: {sensor.humidity():.1f}% | "
118 | f"Status: {sensor.sensor_status()} | "
119 | f"Comfort: {sensor.comfort_level()}"
120 | )
121 |
122 | def temp_alert():
123 | """Alert when temperature exceeds threshold."""
124 | if sensor.temperature() > 28:
125 | print(f"⚠️ HIGH TEMPERATURE ALERT: {sensor.temperature():.1f}°C!")
126 |
127 | def monitor_status():
128 | """Monitor sensor health and report errors."""
129 | if sensor.sensor_status() == "ERROR":
130 | print("🚨 SENSOR ERROR DETECTED!")
131 |
132 | def control_climate():
133 | """Simulated climate control system actions."""
134 | if sensor.comfort_level() == "COMFORTABLE":
135 | return
136 |
137 | temp = sensor.temperature()
138 | if temp > 26:
139 | action = "COOLING"
140 | elif temp < 18:
141 | action = "HEATING"
142 | else:
143 | action = "IDLE"
144 |
145 | print(f"🔄 HVAC ACTION: {action}")
146 |
147 | # Create effects with named functions
148 | log_sensor_eff = Effect(log_sensor)
149 | temp_alert_eff = Effect(temp_alert)
150 | monitor_status_eff = Effect(monitor_status)
151 | control_climate_eff = Effect(control_climate)
152 |
153 | try:
154 | print("Starting IoT sensor monitoring system...")
155 | print("All monitoring, alerts, and climate control will react automatically to sensor changes")
156 | sensor.start_sensor()
157 | time.sleep(15) # Run for 15 seconds
158 | except KeyboardInterrupt:
159 | print("\nDemo interrupted")
160 | finally:
161 | sensor.stop_sensor()
162 | print("Demo completed")
163 |
164 |
165 | if __name__ == "__main__":
166 | demo()
167 |
--------------------------------------------------------------------------------
/examples/iot_temp_monitor.py:
--------------------------------------------------------------------------------
1 | import asyncio
2 | import random
3 | from reaktiv import Signal, Computed, Effect
4 |
5 | async def main():
6 | # Initialize sensor readings (in °C)
7 | sensor1 = Signal(20.0)
8 | sensor2 = Signal(21.0)
9 | sensor3 = Signal(19.5)
10 |
11 | # Compute aggregates: average, minimum, and maximum temperature.
12 | avg_temp = Computed(lambda: (sensor1() + sensor2() + sensor3()) / 3)
13 | min_temp = Computed(lambda: min(sensor1(), sensor2(), sensor3()))
14 | max_temp = Computed(lambda: max(sensor1(), sensor2(), sensor3()))
15 |
16 | # Effect to display current sensor readings and computed statistics.
17 | async def display_aggregates():
18 | print(f"🌡️ Sensor readings: {sensor1():.2f}°C, {sensor2():.2f}°C, {sensor3():.2f}°C")
19 | print(f"📊 Avg: {avg_temp():.2f}°C | ⬇️ Min: {min_temp():.2f}°C | ⬆️ Max: {max_temp():.2f}°C")
20 | print("-------------------------------------------------------------")
21 |
22 | # Schedule the display effect.
23 | display_effect = Effect(display_aggregates)
24 |
25 | # Effect to trigger alerts when values exceed safe limits.
26 | async def temperature_alert():
27 | if avg_temp() > 25:
28 | print("🚨 ALERT: Average temperature is too high! 🔥")
29 | if min_temp() < 15:
30 | print("🚨 ALERT: One or more sensors report a temperature that's too low! ❄️")
31 | if max_temp() > 30:
32 | print("🚨 ALERT: A sensor is overheating! 🔥")
33 |
34 | # Schedule the alert effect.
35 | alert_effect = Effect(temperature_alert)
36 |
37 | def update_sensor(sensor, sensor_name: str):
38 | """
39 | Update a sensor value with a normal drift.
40 | With a 10% chance, inject a fault (a dramatic spike or drop) to trigger alerts.
41 | """
42 | if random.random() < 0.1:
43 | # Fault injection: choose a spike (overheat) or a drop (undercool)
44 | change = random.choice([random.uniform(5.0, 10.0), random.uniform(-10.0, -5.0)])
45 | print(f"[{sensor_name}] ⚠️ Fault injection: {change:+.2f}°C")
46 | else:
47 | # Normal fluctuation
48 | change = random.uniform(-0.5, 1.0)
49 | sensor.update(lambda current: current + change)
50 |
51 | # Simulate periodic sensor updates.
52 | for _ in range(15):
53 | await asyncio.sleep(2)
54 | update_sensor(sensor1, "Sensor1")
55 | update_sensor(sensor2, "Sensor2")
56 | update_sensor(sensor3, "Sensor3")
57 |
58 | # Allow any pending effects to process.
59 | await asyncio.sleep(1)
60 |
61 | if __name__ == '__main__':
62 | asyncio.run(main())
63 |
--------------------------------------------------------------------------------
/examples/napkin_calc.py:
--------------------------------------------------------------------------------
1 | #!/usr/bin/env python3
2 | """Reactive napkin calculator using reaktiv"""
3 |
4 | from reaktiv import Signal as S, Computed as C, Effect as E
5 |
6 | # Input values
7 | salary = S(50000)
8 | bonus = S(5000)
9 | tax_rate = S(0.22)
10 | expenses = S(2500)
11 | months = S(12)
12 |
13 | # Derived calculations
14 | income = C(lambda: salary() + bonus())
15 | taxes = C(lambda: income() * tax_rate())
16 | net = C(lambda: income() - taxes())
17 | annual_expenses = C(lambda: expenses() * months())
18 | savings = C(lambda: net() - annual_expenses())
19 | savings_rate = C(lambda: savings() / net() * 100)
20 |
21 | def display():
22 | print("\n📊 Financial Summary:")
23 | print(f"{'Item':<20} {'Value':>10}")
24 | print(f"{'-'*20} {'-'*10}")
25 | print(f"{'Income':<20} {'$'+str(income()):>10}")
26 | print(f"{'Taxes':<20} {'$'+str(taxes()):>10}")
27 | print(f"{'Net Income':<20} {'$'+str(net()):>10}")
28 | print(f"{'Annual Expenses':<20} {'$'+str(annual_expenses()):>10}")
29 | print(f"{'Savings':<20} {'$'+str(savings()):>10}")
30 | print(f"{'Savings Rate':<20} {f'{savings_rate():.1f}%':>10}")
31 |
32 | table = E(display)
33 |
34 | print("\n--- Initial Values ---")
35 |
36 | print("\n--- After Salary Increase ---")
37 | salary.set(55000)
38 |
39 | print("\n--- After Bonus and Tax Changes ---")
40 | bonus.set(7500)
41 | tax_rate.set(0.24)
42 |
43 | print("\n--- Expense Reduction Strategy ---")
44 | expenses.set(2200)
45 |
46 | if __name__ == "__main__":
47 | print("\nTry it yourself! Change any input value to see calculations update.")
48 | print("Example: salary.set(60000)")
49 |
--------------------------------------------------------------------------------
/examples/nicegui_todo_app.py:
--------------------------------------------------------------------------------
1 | """
2 | Example demonstrating how to integrate reaktiv with NiceGUI to build reactive UIs.
3 |
4 | This example creates a simple todo application that lets you add tasks,
5 | mark them as complete, filter them by status, and automatically updates
6 | all UI components when the underlying data changes.
7 |
8 | To run this example:
9 | 1. pip install reaktiv nicegui
10 | 2. python nicegui_todo_app.py
11 | """
12 |
13 | from reaktiv import Signal, Computed, Effect
14 | from nicegui import ui
15 |
16 | # State module - completely independent from UI
17 | class TodoState:
18 | def __init__(self):
19 | self.todos = Signal([])
20 | self.filter = Signal("all") # all, active, completed
21 |
22 | self.filtered_todos = Computed(lambda: [
23 | todo for todo in self.todos()
24 | if self.filter() == "all"
25 | or (self.filter() == "active" and not todo["completed"])
26 | or (self.filter() == "completed" and todo["completed"])
27 | ])
28 | self.active_count = Computed(lambda:
29 | sum(1 for todo in self.todos() if not todo["completed"])
30 | )
31 | self.completed_count = Computed(lambda:
32 | sum(1 for todo in self.todos() if todo["completed"])
33 | )
34 |
35 | def add_todo(self, text):
36 | self.todos.update(lambda todos: todos + [{"text": text, "completed": False}])
37 |
38 | def toggle_todo(self, index):
39 | self.todos.update(lambda todos: [
40 | {**todo, "completed": not todo["completed"]} if i == index else todo
41 | for i, todo in enumerate(todos)
42 | ])
43 |
44 | def clear_completed(self):
45 | self.todos.update(lambda todos: [todo for todo in todos if not todo["completed"]])
46 |
47 | # Create a state instance
48 | state = TodoState()
49 |
50 | # UI layer can now use the state
51 | with ui.card():
52 | ui.label("Todo App").classes("text-xl")
53 |
54 | # Input for new todos
55 | with ui.row():
56 | new_todo = ui.input("New task")
57 | ui.button("Add", on_click=lambda: [state.add_todo(new_todo.value), new_todo.set_value("")])
58 |
59 | # Todo list - connected to state via Effect
60 | todo_container = ui.column()
61 |
62 | def render_todos():
63 | todo_container.clear()
64 | for i, todo in enumerate(state.filtered_todos()):
65 | with todo_container:
66 | with ui.row():
67 | ui.checkbox(value=todo["completed"], on_change=lambda e, idx=i: state.toggle_todo(idx))
68 | ui.label(todo["text"]).classes("line-through" if todo["completed"] else "")
69 |
70 | # Effect connects state to UI
71 | render_effect = Effect(render_todos)
72 |
73 | # Filter controls
74 | with ui.row():
75 | ui.button("All", on_click=lambda: state.filter.set("all"))
76 | ui.button("Active", on_click=lambda: state.filter.set("active"))
77 | ui.button("Completed", on_click=lambda: state.filter.set("completed"))
78 | ui.button("Clear completed", on_click=lambda: state.clear_completed())
79 |
80 | # Status display - automatically updates
81 | status_label = ui.label()
82 | status_effect = Effect(lambda: status_label.set_text(
83 | f"{state.active_count()} active, {state.completed_count()} completed"
84 | ))
85 |
86 | ui.run()
--------------------------------------------------------------------------------
/examples/numpy_plotting.py:
--------------------------------------------------------------------------------
1 | """
2 | Numpy calculation and plotting example with reaktiv.
3 |
4 | This example demonstrates using reaktiv for efficient computation
5 | with numpy matrices and matplotlib visualization. The expensive
6 | calculations only run when their input parameters change, while
7 | visualization settings can change without triggering recalculation.
8 |
9 | To run this example:
10 | pip install numpy matplotlib ipywidgets
11 | python examples/numpy_plotting.py
12 | """
13 |
14 | import time
15 | import numpy as np
16 | import matplotlib.pyplot as plt
17 | from matplotlib.widgets import Slider, Button
18 | from matplotlib.patches import Rectangle
19 |
20 | from reaktiv import Signal, Computed, Effect, batch
21 |
22 | class ReactiveMatrixVisualizer:
23 | def __init__(self):
24 | # Input parameters - changing these triggers recalculation
25 | self.matrix_size = Signal(100)
26 | self.seed = Signal(42)
27 | self.noise_scale = Signal(0.5)
28 | self.filter_size = Signal(5)
29 |
30 | # Visualization parameters - changing these doesn't trigger recalculation
31 | self.colormap_name = Signal("viridis")
32 | self.show_contour = Signal(False)
33 | self.contour_levels = Signal(10)
34 | self.title_text = Signal("Reactive Matrix Visualization")
35 |
36 | # Add status signals for UI feedback
37 | self.status_message = Signal("")
38 | self.is_computing = Signal(False)
39 |
40 | # Setup the figure with a fixed layout
41 | self.fig = plt.figure(figsize=(10, 8))
42 |
43 | # Create a more stable layout with dedicated areas
44 | from matplotlib import gridspec
45 | self.gs = gridspec.GridSpec(2, 2, height_ratios=[6, 1], width_ratios=[20, 1],
46 | figure=self.fig, hspace=0.05, wspace=0.05)
47 |
48 | # Create the axes for the plot, colorbar and controls
49 | self.ax = self.fig.add_subplot(self.gs[0, 0]) # Main plot in top-left
50 | self.cbar_ax = self.fig.add_subplot(self.gs[0, 1]) # Colorbar in top-right
51 |
52 | # Control area at the bottom spanning both columns
53 | self.controls_area = self.fig.add_subplot(self.gs[1, :])
54 | self.controls_area.axis('off') # Hide the axes for the controls area
55 |
56 | # Status text for feedback
57 | self.status_text = self.fig.text(0.05, 0.25, "", fontsize=10,
58 | bbox=dict(facecolor='yellow', alpha=0.2))
59 |
60 | # Rectangle for highlighting updates
61 | self.highlight_rect = Rectangle((0, 0), 1, 1, fill=False,
62 | edgecolor='red', linewidth=3, visible=False)
63 | self.ax.add_patch(self.highlight_rect)
64 |
65 | # Add computation state signals
66 | self.computing_matrix = Signal(False)
67 | self.computing_filter = Signal(False)
68 | self.computation_status = Signal("")
69 |
70 | # Combine all input parameters into a single computed value
71 | self.input_parameters = Computed(lambda: {
72 | "size": self.matrix_size(),
73 | "seed": self.seed(),
74 | "noise": self.noise_scale(),
75 | "filter_size": self.filter_size()
76 | })
77 |
78 | # Computation time tracking
79 | self.matrix_computation_time = Signal(0.0)
80 | self.filter_computation_time = Signal(0.0)
81 | self.last_computation_time = Signal(0.0) # Combined time
82 |
83 | # Now the expensive computations are TRULY pure functions (no signal setting)
84 | self.random_matrix_with_time = Computed(self._generate_random_matrix_pure)
85 | self.filtered_matrix_with_time = Computed(self._apply_filter_pure)
86 |
87 | # Computed signals for just the matrix data
88 | self.random_matrix = Computed(lambda: self.random_matrix_with_time()["matrix"])
89 | self.filtered_matrix = Computed(lambda: self.filtered_matrix_with_time()["filtered"])
90 |
91 | # Effects to handle UI updates and status messages
92 | self._status_effect = Effect(self._update_status_display)
93 |
94 | # Effects to handle setting time signals
95 | self._matrix_time_effect = Effect(self._update_matrix_time)
96 | self._filter_time_effect = Effect(self._update_filter_time)
97 | self._total_time_effect = Effect(self._update_total_time)
98 |
99 | # Add effects to track computation status
100 | self._matrix_status_effect = Effect(self._track_matrix_computation)
101 | self._filter_status_effect = Effect(self._track_filter_computation)
102 |
103 | # Add UI controls
104 | self._setup_controls()
105 |
106 | # Effect to update the plot when computed values or visualization params change
107 | self._plot_effect = Effect(self._update_plot)
108 |
109 | def _generate_random_matrix_pure(self):
110 | """Generate a random matrix - TRULY PURE function (no signal setting)"""
111 | # Get all parameters from the combined input
112 | params = self.input_parameters()
113 | size = params["size"]
114 | seed = params["seed"]
115 | noise = params["noise"]
116 |
117 | # Log to console only (no signal setting)
118 | print(f"Matrix generation with size={size}, seed={seed}, noise={noise}")
119 | print(f"Generating new {size}×{size} matrix with seed {seed}...")
120 | start_time = time.time()
121 |
122 | # Set the seed for reproducibility
123 | np.random.seed(seed)
124 |
125 | # Generate matrix
126 | matrix = np.random.randn(size, size) * noise
127 |
128 | # Add patterns
129 | x = np.linspace(-5, 5, size)
130 | y = np.linspace(-5, 5, size)
131 | X, Y = np.meshgrid(x, y)
132 |
133 | frequency = max(1, 50 / size)
134 | pattern = np.sin(X * frequency) * np.cos(Y * frequency) * noise * 3
135 | matrix += pattern
136 |
137 | seed_effect = np.sin(X * (seed % 10 + 1) / 5) * np.cos(Y * (seed % 10 + 1) / 5)
138 | matrix += seed_effect * noise * 2
139 |
140 | computation_time = time.time() - start_time
141 | print(f"Matrix generation completed in {computation_time:.3f} seconds")
142 |
143 | # Return matrix, computation time, and parameters used
144 | return {
145 | "matrix": matrix,
146 | "time": computation_time,
147 | "params": {"size": size, "seed": seed}
148 | }
149 |
150 | def _apply_filter_pure(self):
151 | """Apply filter - TRULY PURE function (no signal setting)"""
152 | # Get parameters from the combined input
153 | params = self.input_parameters()
154 | filter_size = params["filter_size"]
155 |
156 | # Log to console only (no signal setting)
157 | print(f"Filter application with filter_size={filter_size}")
158 | print("Applying filter to matrix...")
159 | start_time = time.time()
160 |
161 | # Get matrix result
162 | matrix_result = self.random_matrix_with_time()
163 | matrix = matrix_result["matrix"]
164 |
165 | # Apply filter
166 | if filter_size <= 1:
167 | filtered = matrix
168 | else:
169 | filtered = np.zeros_like(matrix)
170 | m, n = matrix.shape
171 | effect_strength = filter_size / 3.0
172 |
173 | for i in range(m):
174 | for j in range(n):
175 | i_start = max(0, i - filter_size)
176 | i_end = min(m, i + filter_size + 1)
177 | j_start = max(0, j - filter_size)
178 | j_end = min(n, j + filter_size + 1)
179 | window = matrix[i_start:i_end, j_start:j_end]
180 | center_val = matrix[i, j]
181 | filtered[i, j] = center_val * (1 - effect_strength) + np.mean(window) * effect_strength
182 |
183 | computation_time = time.time() - start_time
184 | print(f"Filter application completed in {computation_time:.3f} seconds")
185 |
186 | # Return result with metadata
187 | return {
188 | "filtered": filtered,
189 | "time": computation_time,
190 | "params": {"filter_size": filter_size}
191 | }
192 |
193 | # Effect to update the status display based on status signals
194 | def _update_status_display(self):
195 | """Effect to update the status text UI element based on status signals"""
196 | message = self.status_message()
197 | if message:
198 | self.status_text.set_text(message)
199 | self.status_text.set_visible(True)
200 | else:
201 | self.status_text.set_visible(False)
202 | self.fig.canvas.draw_idle()
203 |
204 | # New methods to handle the side effects via Effects
205 | def _update_matrix_time(self):
206 | """Effect that updates the matrix computation time signal"""
207 | time_value = self.random_matrix_with_time()["time"]
208 | self.matrix_computation_time.set(time_value)
209 |
210 | def _update_filter_time(self):
211 | """Effect that updates the filter computation time signal"""
212 | time_value = self.filtered_matrix_with_time()["time"]
213 | self.filter_computation_time.set(time_value)
214 |
215 | def _update_total_time(self):
216 | """Effect that updates the total computation time signal"""
217 | matrix_time = self.matrix_computation_time()
218 | filter_time = self.filter_computation_time()
219 | self.last_computation_time.set(matrix_time + filter_time)
220 |
221 | # Effect functions to track computation status
222 | def _track_matrix_computation(self):
223 | """Track matrix computation and update status signals"""
224 | # Access result to check current status
225 | matrix_result = self.random_matrix_with_time()
226 | params = matrix_result["params"]
227 |
228 | # Update status message
229 | self.status_message.set(f"Matrix {params['size']}×{params['size']} with seed {params['seed']}")
230 |
231 | def _track_filter_computation(self):
232 | """Track filter computation and update status signals"""
233 | # Access result to check current status
234 | filter_result = self.filtered_matrix_with_time()
235 | filter_size = filter_result["params"]["filter_size"]
236 |
237 | # Update status message
238 | if filter_size > 0:
239 | self.status_message.set(f"Applied filter (size {filter_size})")
240 |
241 | # These methods are now simplified - no more direct UI manipulation from here
242 | def _show_status(self, message):
243 | """Set the status message signal"""
244 | self.status_message.set(message)
245 |
246 | def _clear_status(self):
247 | """Clear the status message signal"""
248 | self.status_message.set("")
249 |
250 | def _flash_highlight(self):
251 | """Flash a highlight around the plot to indicate an update"""
252 | self.highlight_rect.set_visible(True)
253 | self.fig.canvas.draw_idle()
254 |
255 | # Use a timer to hide the highlight after a short delay
256 | timer = self.fig.canvas.new_timer(interval=500) # 500ms
257 | timer.add_callback(self._hide_highlight)
258 | timer.start()
259 |
260 | def _hide_highlight(self):
261 | """Hide the highlight rectangle"""
262 | self.highlight_rect.set_visible(False)
263 | self.fig.canvas.draw_idle()
264 | return False # Stop the timer
265 |
266 | def _update_plot(self):
267 | """Update the plot with current data and visualization settings"""
268 | print("Updating plot...")
269 |
270 | # Get current data and visualization parameters
271 | matrix = self.filtered_matrix()
272 | cmap_name = self.colormap_name()
273 | show_contours = self.show_contour()
274 | contour_levels = self.contour_levels()
275 | title = self.title_text()
276 |
277 | # Clear only the main plot axis, not the whole figure
278 | self.ax.clear()
279 | self.cbar_ax.clear()
280 |
281 | # Re-add the highlight rectangle after clearing
282 | self.highlight_rect = Rectangle((0, 0), 1, 1, fill=False,
283 | edgecolor='red', linewidth=3, visible=False)
284 | self.ax.add_patch(self.highlight_rect)
285 |
286 | # Create the heatmap with enhanced contrast
287 | im = self.ax.imshow(matrix, cmap=cmap_name, interpolation='nearest',
288 | vmin=np.min(matrix) - 0.2*np.std(matrix), # Enhance contrast
289 | vmax=np.max(matrix) + 0.2*np.std(matrix))
290 |
291 | # Add contours if enabled - make them more prominent
292 | if show_contours:
293 | contours = self.ax.contour(matrix, levels=contour_levels,
294 | colors='k', alpha=0.7, linewidths=1.5)
295 | self.ax.clabel(contours, inline=True, fontsize=8)
296 |
297 | # Add colorbar to the dedicated axis
298 | cbar = self.fig.colorbar(im, cax=self.cbar_ax)
299 | cbar.set_label(f'Colormap: {cmap_name}')
300 |
301 | # Set title with computation info
302 | comp_time = self.last_computation_time()
303 | matrix_size = self.matrix_size()
304 | filter_size = self.filter_size()
305 | self.ax.set_title(f"{title}\n{matrix_size}×{matrix_size} matrix, filter size {filter_size}, computed in {comp_time:.3f}s")
306 |
307 | # Add grid for better visual reference
308 | self.ax.grid(alpha=0.3, linestyle='--')
309 |
310 | # Clear status text
311 | self._clear_status()
312 |
313 | # Flash highlight to indicate update
314 | self._flash_highlight()
315 |
316 | # Draw the updated figure
317 | self.fig.canvas.draw_idle()
318 | print("Plot updated!")
319 |
320 | def _setup_controls(self):
321 | """Set up interactive controls"""
322 | # Add sliders for parameters
323 | axcolor = 'lightgoldenrodyellow'
324 |
325 | # Computation parameter controls - sliders
326 | ax_size = plt.axes([0.25, 0.20, 0.65, 0.03], facecolor=axcolor)
327 | ax_noise = plt.axes([0.25, 0.15, 0.65, 0.03], facecolor=axcolor)
328 | ax_filter = plt.axes([0.25, 0.10, 0.65, 0.03], facecolor=axcolor)
329 | ax_seed = plt.axes([0.25, 0.05, 0.65, 0.03], facecolor=axcolor) # Fixed: added missing height parameter
330 |
331 | # Store sliders as instance variables
332 | self.size_slider = Slider(ax_size, 'Matrix Size', 50, 500, valinit=self.matrix_size(), valstep=10)
333 | self.noise_slider = Slider(ax_noise, 'Noise Scale', 0.1, 2.0, valinit=self.noise_scale())
334 | self.filter_slider = Slider(ax_filter, 'Filter Size', 0, 10, valinit=self.filter_size(), valstep=1)
335 | self.seed_slider = Slider(ax_seed, 'Random Seed', 0, 100, valinit=self.seed(), valstep=1)
336 |
337 | # Visualization controls - MOVED UNDER SLIDERS
338 | # Position buttons on a row below the sliders
339 | button_y = 0.01 # Positioned below the lowest slider
340 | button_width = 0.15
341 | button_spacing = 0.02
342 |
343 | ax_cmap = plt.axes([0.15, button_y, button_width, 0.03], facecolor=axcolor)
344 | ax_contour = plt.axes([0.15 + button_width + button_spacing, button_y, button_width, 0.03], facecolor=axcolor)
345 | ax_contour_levels = plt.axes([0.15 + 2*(button_width + button_spacing), button_y, button_width, 0.03], facecolor=axcolor)
346 | ax_reset = plt.axes([0.15 + 3*(button_width + button_spacing), button_y, button_width, 0.03], facecolor=axcolor)
347 |
348 | # Store buttons as instance variables
349 | self.cmap_button = Button(ax_cmap, 'Change Colormap')
350 | self.contour_button = Button(ax_contour, 'Toggle Contours')
351 | self.contour_levels_button = Button(ax_contour_levels, 'Contour Levels')
352 | self.reset_button = Button(ax_reset, 'Reset')
353 |
354 | # Define update functions with enhanced feedback
355 | def update_size(val):
356 | size_val = int(val)
357 | print(f"SLIDER: Changing matrix size to {size_val}...")
358 | self._show_status(f"Changing matrix size to {size_val}...")
359 | self.matrix_size.set(size_val)
360 |
361 | def update_noise(val):
362 | print(f"SLIDER: Changing noise to {val:.2f}...")
363 | self._show_status(f"Adjusting noise scale to {val:.2f}...")
364 | self.noise_scale.set(val)
365 |
366 | def update_filter(val):
367 | filter_val = int(val)
368 | print(f"SLIDER: Changing filter to {filter_val}...")
369 | self._show_status(f"Setting filter size to {filter_val}...")
370 | self.filter_size.set(filter_val)
371 |
372 | def update_seed(val):
373 | seed_val = int(val)
374 | print(f"SLIDER: Changing seed to {seed_val}...")
375 | self._show_status(f"Changing random seed to {seed_val}...")
376 | self.seed.set(seed_val)
377 |
378 | def cycle_colormap(val):
379 | cmaps = ['viridis', 'plasma', 'inferno', 'magma', 'cividis', 'hot', 'cool']
380 | current = self.colormap_name()
381 | idx = (cmaps.index(current) + 1) % len(cmaps) if current in cmaps else 0
382 | new_cmap = cmaps[idx]
383 | self._show_status(f"Changing colormap to {new_cmap}...")
384 | self.colormap_name.set(new_cmap)
385 |
386 | def toggle_contour(val):
387 | new_state = not self.show_contour()
388 | state_text = "ON" if new_state else "OFF"
389 | self._show_status(f"Toggling contours {state_text}...")
390 | self.show_contour.set(new_state)
391 |
392 | def cycle_contour_levels(val):
393 | levels = [5, 10, 15, 20, 30]
394 | current = self.contour_levels()
395 | idx = (levels.index(current) + 1) % len(levels) if current in levels else 0
396 | new_levels = levels[idx]
397 | self._show_status(f"Setting contour levels to {new_levels}...")
398 | self.contour_levels.set(new_levels)
399 |
400 | def reset(val):
401 | self._show_status("Resetting all parameters...")
402 | with batch():
403 | self.size_slider.set_val(100)
404 | self.noise_slider.set_val(0.5)
405 | self.filter_slider.set_val(5)
406 | self.seed_slider.set_val(42)
407 | self.colormap_name.set('viridis')
408 | self.show_contour.set(False)
409 | self.contour_levels.set(10)
410 |
411 | # Connect callbacks
412 | self.size_slider.on_changed(update_size)
413 | self.noise_slider.on_changed(update_noise)
414 | self.filter_slider.on_changed(update_filter)
415 | self.seed_slider.on_changed(update_seed)
416 |
417 | self.cmap_button.on_clicked(cycle_colormap)
418 | self.contour_button.on_clicked(toggle_contour)
419 | self.contour_levels_button.on_clicked(cycle_contour_levels)
420 | self.reset_button.on_clicked(reset)
421 |
422 | def show(self):
423 | """Display the interactive visualization"""
424 | # Make sure we use blocking mode to keep the window open
425 | plt.ioff() # Turn off interactive mode to ensure window stays open
426 | plt.show(block=True) # Explicitly use blocking mode
427 |
428 |
429 | if __name__ == "__main__":
430 | print("Starting Reactive Matrix Visualizer...")
431 | print("Notice how expensive computations only run when computation parameters change,")
432 | print("while visualization settings can be changed without triggering recalculation.")
433 | visualizer = ReactiveMatrixVisualizer()
434 | visualizer.show()
435 |
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/examples/polling_system.py:
--------------------------------------------------------------------------------
1 | import asyncio
2 | from reaktiv import Signal, Computed, Effect
3 |
4 | async def main():
5 | candidate_a = Signal(100)
6 | candidate_b = Signal(100)
7 |
8 | total_votes = Computed(lambda: candidate_a() + candidate_b())
9 | percent_a = Computed(lambda: (candidate_a() / total_votes()) * 100)
10 | percent_b = Computed(lambda: (candidate_b() / total_votes()) * 100)
11 |
12 | async def display_results():
13 | print(f"Candidate A: {candidate_a()} votes ({percent_a():.1f}%)")
14 | print(f"Candidate B: {candidate_b()} votes ({percent_b():.1f}%)")
15 | print(f"Total: {total_votes()} votes\n")
16 |
17 | async def check_dominance():
18 | if percent_a() >= 60:
19 | print("📊 ALERT: Candidate A has a significant lead!\n")
20 | elif percent_b() >= 60:
21 | print("📊 ALERT: Candidate B has a significant lead!\n")
22 |
23 | # Assign effects to variables to ensure they are retained
24 | display_effect = Effect(display_results)
25 | alert_effect = Effect(check_dominance)
26 |
27 | for _ in range(3):
28 | await asyncio.sleep(1)
29 | candidate_a.update(lambda x: x + 40)
30 | candidate_b.update(lambda x: x + 10)
31 |
32 | await asyncio.sleep(1)
33 |
34 | asyncio.run(main())
--------------------------------------------------------------------------------
/examples/reactive_excel.py:
--------------------------------------------------------------------------------
1 | import asyncio
2 | from reaktiv import Signal, Computed, Effect
3 |
4 | async def main():
5 | # Define input cells (cells you can edit)
6 | A1 = Signal(10) # Cell A1
7 | B1 = Signal(20) # Cell B1
8 | C1 = Signal(30) # Cell C1
9 |
10 | # Define computed (formula) cells:
11 | # D1 simulates "=SUM(A1, B1, C1)"
12 | D1 = Computed(lambda: A1() + B1() + C1())
13 |
14 | # E1 simulates "=AVERAGE(A1, B1, C1)"
15 | E1 = Computed(lambda: (A1() + B1() + C1()) / 3)
16 |
17 | # F1 simulates "=PRODUCT(A1, B1, C1)"
18 | F1 = Computed(lambda: A1() * B1() * C1())
19 |
20 | # Effect to print a simple spreadsheet view whenever any cell changes.
21 | async def print_spreadsheet():
22 | print("\n📊 Reactive Excel Simulation")
23 | print("+------+------+------+-------+----------+------------+")
24 | print("| Cell | A | B | C | D | E |")
25 | print("+------+------+------+-------+----------+------------+")
26 | print(f"| 1 | {A1():^4} | {B1():^4} | {C1():^4} | {D1():^6} | {E1():^8.2f} |")
27 | print("+------+------+------+-------+----------+------------+")
28 | print(f"| F1 (Product) = {F1()}")
29 | print("+-----------------------------------------+\n")
30 |
31 | # Schedule the spreadsheet printing effect.
32 | # (Assigning it to a variable ensures it won't be garbage collected.)
33 | sheet_effect = Effect(print_spreadsheet)
34 |
35 | # Simulate editing cells with delays so the editing messages are visible.
36 | await asyncio.sleep(2)
37 | print("✏️ Editing A1 → 15")
38 | A1.set(15)
39 |
40 | await asyncio.sleep(2)
41 | print("✏️ Editing B1 → 25")
42 | B1.set(25)
43 |
44 | await asyncio.sleep(2)
45 | print("✏️ Editing C1 → 35")
46 | C1.set(35)
47 |
48 | await asyncio.sleep(2)
49 | print("✏️ Editing A1 → 50")
50 | A1.set(50)
51 |
52 | await asyncio.sleep(2)
53 | print("✏️ Editing B1 → 5")
54 | B1.set(5)
55 |
56 | await asyncio.sleep(2)
57 | print("✏️ Editing C1 → 10")
58 | C1.set(10)
59 |
60 | # Allow a moment for the final effect updates.
61 | await asyncio.sleep(2)
62 |
63 | if __name__ == '__main__':
64 | asyncio.run(main())
65 |
--------------------------------------------------------------------------------
/examples/stock_ticker.py:
--------------------------------------------------------------------------------
1 | import asyncio
2 | from reaktiv import batch, Signal, Computed, Effect
3 |
4 | async def main():
5 | # Real-time stock prices
6 | apple_price = Signal(195.00)
7 | google_price = Signal(2750.00)
8 |
9 | # User's portfolio
10 | shares = Signal({
11 | 'AAPL': 100,
12 | 'GOOGL': 50
13 | })
14 |
15 | # Computed total portfolio value
16 | portfolio_value = Computed(lambda: (
17 | shares()['AAPL'] * apple_price() +
18 | shares()['GOOGL'] * google_price()
19 | ))
20 |
21 | # Price alert system
22 | async def check_alerts():
23 | if apple_price() > 200:
24 | print("📈 AAPL alert: Above $200!")
25 | if google_price() < 2700:
26 | print("📉 GOOGL alert: Below $2700!")
27 |
28 | # Automatic updates
29 | async def live_updates():
30 | # Simulate real-time updates
31 | while True:
32 | await asyncio.sleep(1)
33 | with batch():
34 | apple_price.update(lambda v: v * 1.01) # +1%
35 | google_price.update(lambda v: v * 0.995) # -0.5%
36 |
37 | print(f"🍏 AAPL: ${apple_price():,.2f} 🌐 GOOGL: ${google_price():,.2f}")
38 |
39 | # Track portfolio value
40 | async def monitor_portfolio():
41 | print(f"💰 Current value: ${portfolio_value():,.2f}")
42 |
43 | # Set up effects
44 | alerts_effect = Effect(check_alerts)
45 | portfolio_effect = Effect(monitor_portfolio)
46 |
47 | # Start live updates
48 | updates_task = asyncio.create_task(live_updates())
49 |
50 | # Run for 5 seconds
51 | await asyncio.sleep(5)
52 |
53 | asyncio.run(main())
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/mkdocs.yml:
--------------------------------------------------------------------------------
1 | site_name: reaktiv
2 | site_description: Reactive Computation Graphs for Python with first-class async support
3 | site_url: https://reaktiv.readthedocs.io/
4 |
5 | theme:
6 | name: material
7 | palette:
8 | primary: indigo
9 | accent: indigo
10 | features:
11 | - navigation.tabs
12 | - navigation.sections
13 | - navigation.expand
14 | - navigation.top
15 | - search.suggest
16 | - search.highlight
17 |
18 | repo_url: https://github.com/buiapp/reaktiv
19 | repo_name: buiapp/reaktiv
20 |
21 | markdown_extensions:
22 | - pymdownx.highlight
23 | - pymdownx.superfences:
24 | custom_fences:
25 | - name: mermaid
26 | class: mermaid
27 | format: !!python/name:pymdownx.superfences.fence_code_format
28 | - admonition
29 | - toc:
30 | permalink: true
31 |
32 | plugins:
33 | - search
34 | - mermaid2
35 | - mkdocstrings:
36 | default_handler: python
37 | handlers:
38 | python:
39 | options:
40 | show_source: true
41 |
42 | nav:
43 | - Home: index.md
44 | - Getting Started:
45 | - Installation: installation.md
46 | - Quick Start: quickstart.md
47 | - Why reaktiv?: why-reaktiv.md
48 | - Core Concepts: core-concepts.md
49 | - API Reference:
50 | - Signal: api/signal.md
51 | - Computed Signal: api/compute-signal.md
52 | - Effect: api/effect.md
53 | - Utils: api/utils.md
54 | - Advanced:
55 | - Advanced Features: advanced-features.md
56 | - Examples:
57 | - Examples: examples/index.md
--------------------------------------------------------------------------------
/pyproject.toml:
--------------------------------------------------------------------------------
1 | [build-system]
2 | requires = ["setuptools>=65", "wheel"]
3 | build-backend = "setuptools.build_meta"
4 |
5 | [tool.setuptools]
6 | license-files = []
7 |
8 | [project]
9 | name = "reaktiv"
10 | version = "0.14.9"
11 | description = "Reactive signals for Python with async support"
12 | readme = "README.md"
13 | authors = [{name = "Tuan Anh Bui", email = "mail@bui.app"}]
14 | license = {text = "MIT"}
15 | classifiers = [
16 | "License :: OSI Approved :: MIT License",
17 | "Programming Language :: Python :: 3",
18 | "Programming Language :: Python :: 3.9",
19 | "Programming Language :: Python :: 3.10",
20 | "Programming Language :: Python :: 3.11",
21 | "Programming Language :: Python :: 3.12",
22 | ]
23 | requires-python = ">=3.9"
24 | dependencies = []
25 |
26 | [dependency-groups]
27 | dev = [
28 | "pyright>=1.1.398",
29 | "pytest>=7.0",
30 | "pytest-asyncio>=0.20",
31 | "pytest-timeout>=2.3.1",
32 | ]
33 |
34 | [project.urls]
35 | Homepage = "https://github.com/buiapp/reaktiv"
36 |
37 | [tool.pytest.ini_options]
38 | asyncio_mode = "strict"
39 | testpaths = ["tests"]
40 | asyncio_default_fixture_loop_scope = "function"
41 | addopts = "-v"
42 |
--------------------------------------------------------------------------------
/pyrightconfig.json:
--------------------------------------------------------------------------------
1 | {
2 | "include": [
3 | "src"
4 | ],
5 | "exclude": [
6 | "**/__pycache__",
7 | "**/node_modules",
8 | "**/.venv",
9 | "build",
10 | "dist"
11 | ],
12 | "typeCheckingMode": "basic",
13 | "useLibraryCodeForTypes": true,
14 | "reportMissingImports": true,
15 | "reportMissingTypeStubs": true,
16 | "pythonVersion": "3.9",
17 | "executionEnvironments": [
18 | {
19 | "root": "reaktiv"
20 | }
21 | ]
22 | }
--------------------------------------------------------------------------------
/src/reaktiv/__init__.py:
--------------------------------------------------------------------------------
1 | """
2 | Reactive signals for Python with first-class async support
3 | """
4 | from .core import Signal, ComputeSignal, Effect, Computed, batch, untracked, signal, computed, effect
5 | from .utils import to_async_iter
6 | from .operators import filter_signal, debounce_signal, throttle_signal, pairwise_signal
7 |
8 | __version__ = "0.14.9"
9 | __all__ = [
10 | "Signal",
11 | "ComputeSignal",
12 | "Computed",
13 | "Effect",
14 | "batch",
15 | "untracked",
16 | "to_async_iter",
17 | "filter_signal",
18 | "debounce_signal",
19 | "throttle_signal",
20 | "pairwise_signal",
21 | "signal",
22 | "computed",
23 | "effect",
24 | ]
--------------------------------------------------------------------------------
/src/reaktiv/operators.py:
--------------------------------------------------------------------------------
1 | import asyncio
2 | import time
3 | from typing import TypeVar, Callable, Generic, Optional, Union, Set, List, Tuple, Any
4 | from weakref import WeakSet
5 | from .core import (
6 | Signal, ComputeSignal, Effect, _current_effect, Subscriber, debug_log,
7 | _process_sync_effects, _batch_depth
8 | )
9 |
10 | T = TypeVar("T")
11 |
12 | # --------------------------------------------------
13 | # Base Class for Operator Signals
14 | # --------------------------------------------------
15 |
16 | class _OperatorSignal(Generic[T]):
17 | """A read-only signal produced by an operator. Implements methods for duck typing."""
18 | def __init__(self, initial_value: T, *, equal: Optional[Callable[[T, T], bool]] = None):
19 | self._value = initial_value
20 | self._subscribers: WeakSet[Subscriber] = WeakSet()
21 | self._equal = equal or (lambda a, b: a is b) # Default to identity check like Signal
22 | self._internal_effect: Optional[Effect] = None
23 | self._disposed = False
24 | debug_log(f"OperatorSignal initialized with value: {initial_value}")
25 |
26 | def __call__(self) -> T:
27 | return self.get()
28 |
29 | def get(self) -> T:
30 | if self._disposed:
31 | debug_log("Attempted to get value from disposed OperatorSignal")
32 | # Return last known value
33 | return self._value
34 |
35 | tracker = _current_effect.get(None)
36 | if tracker is not None:
37 | # Track this operator signal itself as a dependency.
38 | # The tracker's add_dependency method should call our subscribe method.
39 | # We provide the necessary methods (subscribe/unsubscribe) via duck typing.
40 | tracker.add_dependency(self) # type: ignore
41 | debug_log(f"OperatorSignal get() called, dependency added for tracker: {tracker}")
42 |
43 | debug_log(f"OperatorSignal get() returning value: {self._value}")
44 | return self._value
45 |
46 | def _update_value(self, new_value: T):
47 | """Internal method to update the value and notify subscribers."""
48 | if self._disposed:
49 | return
50 | debug_log(f"OperatorSignal _update_value() called with new_value: {new_value} (old_value: {self._value})")
51 | if self._equal(self._value, new_value):
52 | debug_log("OperatorSignal _update_value() - new_value considered equal; no update.")
53 | return
54 |
55 | self._value = new_value
56 | debug_log(f"OperatorSignal value updated to: {new_value}, notifying subscribers.")
57 |
58 | # Determine if this update is happening outside a batch
59 | is_top_level_trigger = _batch_depth == 0
60 | # No need to increment update cycle here, handled by source/batch
61 |
62 | # Notify own subscribers
63 | subscribers_to_notify = list(self._subscribers)
64 | for subscriber in subscribers_to_notify:
65 | debug_log(f"OperatorSignal notifying subscriber: {subscriber}")
66 | if hasattr(subscriber, 'notify') and callable(subscriber.notify):
67 | subscriber.notify()
68 | else:
69 | debug_log(f"OperatorSignal found invalid subscriber: {subscriber}, removing.")
70 | self._subscribers.discard(subscriber)
71 |
72 | # Process sync effects immediately if this update is not part of a batch
73 | if is_top_level_trigger:
74 | debug_log("OperatorSignal update is top-level, processing sync effects.")
75 | _process_sync_effects()
76 | else:
77 | debug_log("OperatorSignal update is inside a batch, deferring effect processing.")
78 |
79 | # --- Methods for Duck Typing as a Dependency Source ---
80 |
81 | def subscribe(self, subscriber: Subscriber) -> None:
82 | """Allows trackers (Effects, ComputeSignals) to subscribe to this signal."""
83 | if not self._disposed:
84 | self._subscribers.add(subscriber)
85 | debug_log(f"Subscriber {subscriber} added to OperatorSignal {self}.")
86 |
87 | def unsubscribe(self, subscriber: Subscriber) -> None:
88 | """Allows trackers to unsubscribe from this signal."""
89 | self._subscribers.discard(subscriber)
90 | debug_log(f"Subscriber {subscriber} removed from OperatorSignal {self}.")
91 |
92 | # --- Methods for Duck Typing for internal _current_effect usage ---
93 | # These might be called if this signal itself is the tracker (which it isn't)
94 | # or if the tracker.add_dependency implementation expects them.
95 |
96 | def add_dependency(self, signal: Union[Signal, ComputeSignal, '_OperatorSignal']) -> None:
97 | """Satisfies DependencyTracker protocol via duck typing. No-op for OperatorSignal."""
98 | # This signal relies on its internal Effect for tracking *its* sources.
99 | # It does not track other signals directly via this method.
100 | debug_log(f"OperatorSignal.add_dependency called (likely NO-OP needed): {signal}")
101 | pass
102 |
103 | def notify(self) -> None:
104 | """Satisfies Subscriber protocol via duck typing. No-op for OperatorSignal."""
105 | # This signal is notified by its internal Effect, not directly by its sources.
106 | debug_log(f"OperatorSignal.notify called (likely NO-OP needed)")
107 | pass
108 |
109 | # --- Cleanup ---
110 |
111 | def dispose(self):
112 | """Clean up the internal effect and resources."""
113 | debug_log(f"OperatorSignal dispose() called for {self}")
114 | if self._disposed:
115 | return
116 | self._disposed = True
117 | if self._internal_effect:
118 | debug_log(f"Disposing internal effect for {self}")
119 | self._internal_effect.dispose()
120 | self._internal_effect = None
121 | # Clear subscribers to release references
122 | self._subscribers.clear()
123 | debug_log(f"OperatorSignal {self} disposed.")
124 |
125 | def __del__(self):
126 | # Attempt cleanup when garbage collected, though explicit dispose() is preferred
127 | if not self._disposed:
128 | # Avoid running complex logic or logging in __del__ if possible
129 | # self.dispose() # Calling dispose() here can be risky
130 | pass
131 |
132 |
133 | # --------------------------------------------------
134 | # Operator Functions
135 | # --------------------------------------------------
136 |
137 | def filter_signal(
138 | source: Union[Signal[T], ComputeSignal[T], _OperatorSignal[T]],
139 | predicate: Callable[[T], bool]
140 | ) -> _OperatorSignal[Optional[T]]:
141 | """
142 | Creates a read-only signal that only emits values from the source signal
143 | that satisfy the predicate function.
144 |
145 | The initial value will be the source's initial value if it passes the predicate.
146 | If the initial value doesn't pass the predicate, it will still be used as the
147 | initial state of the returned signal, but no notifications will be triggered
148 | for this initial value.
149 |
150 | This operator is synchronous and does not require an asyncio event loop.
151 | """
152 | # Get initial value without tracking dependency here
153 | initial_source_value = source.get()
154 | initial_value_passes = False
155 | try:
156 | initial_value_passes = predicate(initial_source_value)
157 | except Exception as e:
158 | debug_log(f"Filter predicate failed on initial value: {e}")
159 |
160 | # Determine the correct initial value for the filtered signal
161 | # If the initial source value passes, use it. Otherwise, use None.
162 | # We might need a more sophisticated way to handle non-None types later.
163 | initial_filtered_value = initial_source_value if initial_value_passes else None
164 |
165 | # Create the operator signal instance
166 | source_equal = getattr(source, '_equal', None)
167 | # The type checker needs help here as initial_filtered_value can be None
168 | filtered_sig: _OperatorSignal[Optional[T]] = _OperatorSignal(initial_filtered_value, equal=source_equal)
169 |
170 | # Define the effect function
171 | def _run_filter():
172 | # This effect runs whenever the source changes
173 | value = source.get() # Track source as dependency inside effect
174 | if predicate(value):
175 | filtered_sig._update_value(value)
176 | # If predicate is false, we don't update. The signal retains its last valid value.
177 | # Consider if we should update to None when predicate becomes false?
178 | # Current behavior: keeps last valid value.
179 |
180 | # Create the internal effect
181 | internal_effect = Effect(_run_filter)
182 | filtered_sig._internal_effect = internal_effect
183 |
184 | return filtered_sig
185 |
186 | def debounce_signal(
187 | source: Union[Signal[T], ComputeSignal[T], _OperatorSignal[T]],
188 | delay_seconds: float
189 | ) -> _OperatorSignal[T]:
190 | """
191 | Creates a read-only signal that emits a value from the source signal
192 | only after a particular time span has passed without another source emission.
193 |
194 | Note: This operator requires a running asyncio event loop to manage its internal timer.
195 | """
196 | initial_source_value = source.get()
197 | source_equal = getattr(source, '_equal', None)
198 | debounced_sig = _OperatorSignal(initial_source_value, equal=source_equal)
199 |
200 | timer_handle: Optional[asyncio.TimerHandle] = None
201 | pending_value: Optional[T] = None
202 | has_pending_value = False
203 |
204 | def _emit_debounced():
205 | nonlocal timer_handle, has_pending_value, pending_value
206 | if has_pending_value:
207 | # Type ignore justification: has_pending_value ensures pending_value is set
208 | debounced_sig._update_value(pending_value) # type: ignore
209 | has_pending_value = False
210 | timer_handle = None # Clear handle after firing or cancellation
211 |
212 | # Define the effect function (must be async for timer)
213 | async def _run_debounce(on_cleanup: Callable[[Callable[[], None]], None]):
214 | nonlocal timer_handle, pending_value, has_pending_value
215 | # Capture the latest value from source (tracks dependency)
216 | current_value = source.get()
217 | pending_value = current_value
218 | has_pending_value = True
219 | debug_log(f"Debounce: captured value {current_value}")
220 |
221 | # Cancel existing timer if any
222 | if timer_handle:
223 | debug_log("Debounce: cancelling previous timer")
224 | timer_handle.cancel()
225 | timer_handle = None # Ensure handle is cleared immediately
226 |
227 | # Schedule new timer
228 | try:
229 | loop = asyncio.get_running_loop()
230 | debug_log(f"Debounce: scheduling timer for {delay_seconds}s")
231 | timer_handle = loop.call_later(delay_seconds, _emit_debounced)
232 | except RuntimeError:
233 | debug_log("Debounce: No running event loop found. Cannot schedule timer.")
234 | pass
235 |
236 |
237 | # Cleanup function to cancel timer if effect is destroyed/re-run
238 | def cleanup():
239 | nonlocal timer_handle
240 | if timer_handle:
241 | debug_log("Debounce: cleanup cancelling timer")
242 | timer_handle.cancel()
243 | timer_handle = None
244 | on_cleanup(cleanup)
245 |
246 | # Create the internal effect
247 | internal_effect = Effect(_run_debounce) # Effect detects async automatically
248 | debounced_sig._internal_effect = internal_effect
249 |
250 | return debounced_sig
251 |
252 | def throttle_signal(
253 | source: Union[Signal[T], ComputeSignal[T], _OperatorSignal[T]],
254 | interval_seconds: float,
255 | leading: bool = True,
256 | trailing: bool = False
257 | ) -> _OperatorSignal[T]:
258 | """
259 | Creates a read-only signal that emits a value from the source signal,
260 | then ignores subsequent source emissions for a specified duration.
261 | Can optionally emit a trailing value. Uses non-shortcut API.
262 |
263 | Note: This operator requires a running asyncio event loop to manage its internal timer(s).
264 | """
265 | initial_source_value = source.get()
266 | source_equal = getattr(source, '_equal', None)
267 | throttled_sig = _OperatorSignal(initial_source_value, equal=source_equal)
268 |
269 | timer_handle: Optional[asyncio.TimerHandle] = None
270 | trailing_value: Optional[T] = None
271 | has_trailing_value = False
272 | last_emit_time: float = -interval_seconds - 1 # Ensure first emit is allowed if leading
273 |
274 | def _emit_trailing():
275 | nonlocal timer_handle, has_trailing_value, trailing_value, last_emit_time
276 | timer_handle = None # Timer fired or was cancelled
277 | if trailing and has_trailing_value:
278 | debug_log(f"Throttle: emitting trailing value {trailing_value}")
279 | # Type ignore justification: has_trailing_value ensures trailing_value is set
280 | current_time = time.monotonic()
281 | throttled_sig._update_value(trailing_value) # type: ignore
282 | last_emit_time = current_time # Update last emit time for trailing emit
283 | has_trailing_value = False
284 | # If not trailing or no trailing value, do nothing
285 |
286 | async def _run_throttle(on_cleanup: Callable[[Callable[[], None]], None]):
287 | nonlocal last_emit_time, timer_handle, trailing_value, has_trailing_value
288 | current_time = time.monotonic()
289 | value = source.get() # Track source dependency
290 | debug_log(f"Throttle: received value {value} at {current_time:.4f} (last emit: {last_emit_time:.4f})")
291 |
292 | if trailing:
293 | trailing_value = value
294 | has_trailing_value = True
295 |
296 | def cleanup():
297 | nonlocal timer_handle
298 | if timer_handle:
299 | debug_log("Throttle: cleanup cancelling timer")
300 | timer_handle.cancel()
301 | timer_handle = None
302 | on_cleanup(cleanup)
303 |
304 | time_since_last_emit = current_time - last_emit_time
305 | is_interval_passed = time_since_last_emit >= interval_seconds
306 |
307 | if is_interval_passed:
308 | debug_log("Throttle: interval passed")
309 | if timer_handle:
310 | timer_handle.cancel()
311 | timer_handle = None
312 |
313 | if leading:
314 | debug_log(f"Throttle: emitting leading value {value}")
315 | # Store value before potential update
316 | value_before_update = throttled_sig._value
317 | throttled_sig._update_value(value)
318 | # Check if the value actually changed before updating last_emit_time
319 | if not throttled_sig._equal(value_before_update, throttled_sig._value):
320 | debug_log(f"Throttle: Leading value caused update, updating last_emit_time")
321 | last_emit_time = current_time
322 | has_trailing_value = False # Leading emit consumed the value
323 | else:
324 | debug_log(f"Throttle: Leading value did not cause update, last_emit_time unchanged")
325 |
326 | elif trailing:
327 | debug_log(f"Throttle: interval passed, leading=False, scheduling trailing timer for {interval_seconds}s")
328 | try:
329 | loop = asyncio.get_running_loop()
330 | if not timer_handle: # Avoid rescheduling if already scheduled
331 | timer_handle = loop.call_later(interval_seconds, _emit_trailing)
332 | except RuntimeError:
333 | debug_log("Throttle: No running event loop found. Cannot schedule timer.")
334 | pass
335 |
336 | else: # Interval has *not* passed
337 | debug_log("Throttle: within interval")
338 | if trailing and not timer_handle:
339 | remaining_time = interval_seconds - time_since_last_emit
340 | debug_log(f"Throttle: within interval, scheduling trailing timer for {remaining_time:.4f}s")
341 | try:
342 | loop = asyncio.get_running_loop()
343 | timer_handle = loop.call_later(remaining_time, _emit_trailing)
344 | except RuntimeError:
345 | debug_log("Throttle: No running event loop found. Cannot schedule timer.")
346 | pass
347 |
348 | # Create the internal effect
349 | internal_effect = Effect(_run_throttle)
350 | throttled_sig._internal_effect = internal_effect
351 |
352 | return throttled_sig
353 |
354 | # Sentinel object for pairwise
355 | _NO_VALUE = object()
356 |
357 | def pairwise_signal(
358 | source: Union[Signal[T], ComputeSignal[T], _OperatorSignal[T]],
359 | emit_on_first: bool = False
360 | ) -> _OperatorSignal[Optional[Tuple[Optional[T], T]]]:
361 | """
362 | Creates a read-only signal that emits a tuple containing the previous
363 | and current values from the source signal.
364 |
365 | Args:
366 | source: The input signal.
367 | emit_on_first: If True, emits `(None, first_value)` when the source
368 | emits its first value. If False (default), the first
369 | emission from the source does not produce an output,
370 | and the second emission produces `(first_value, second_value)`.
371 |
372 | Returns:
373 | An operator signal emitting tuples of `(previous, current)` values.
374 | The type of `previous` is `Optional[T]`. The initial value of the
375 | signal before any valid pair is emitted is `None`.
376 | """
377 | previous_value: Any = _NO_VALUE
378 | # Get initial value without tracking dependency here
379 | initial_source_value = source.get()
380 |
381 | # Determine the correct initial value for the pairwise signal
382 | initial_pairwise_value: Optional[Tuple[Optional[T], T]] = None
383 | if emit_on_first:
384 | # If emit_on_first, the initial state reflects the first pair.
385 | initial_pairwise_value = (None, initial_source_value)
386 | # Store the initial source value as the "previous" for the *next* run
387 | previous_value = initial_source_value
388 | # else: initial_pairwise_value remains None, previous_value remains _NO_VALUE
389 |
390 | # Initialize the signal with the calculated initial value.
391 | # Add explicit type hint here to match the return signature
392 | pairwise_sig: _OperatorSignal[Optional[Tuple[Optional[T], T]]] = _OperatorSignal(initial_pairwise_value)
393 | debug_log(f"Pairwise: Initialized signal with {initial_pairwise_value}. emit_on_first={emit_on_first}")
394 |
395 | def _run_pairwise():
396 | nonlocal previous_value
397 | # Get current value and track source dependency
398 | current_value = source.get()
399 |
400 | # Get the source's equality function
401 | default_equal = lambda a, b: a is b
402 | source_equal = getattr(source, '_equal', default_equal)
403 |
404 | if source_equal is None:
405 | source_equal = default_equal
406 |
407 | # Check if the current value is the same as the previous one.
408 | is_same_as_previous = (previous_value is not _NO_VALUE) and source_equal(previous_value, current_value)
409 |
410 | if is_same_as_previous:
411 | debug_log(f"Pairwise: current value {current_value} is same as previous {previous_value}, skipping update.")
412 | return # Skip emission
413 |
414 | output_value: Optional[Tuple[Optional[T], T]] = None
415 | should_emit = False
416 |
417 | if previous_value is _NO_VALUE:
418 | # This case should now only happen if emit_on_first was False
419 | # and this is the first value received. We just store it.
420 | debug_log(f"Pairwise (emit_on_first=False): First run, storing previous={current_value}, no emission.")
421 | pass # No emission needed yet
422 | else:
423 | # This is a subsequent run. Prepare the pair.
424 | debug_log(f"Pairwise: Preparing ({previous_value}, {current_value})")
425 | output_value = (previous_value, current_value)
426 | should_emit = True
427 |
428 | # Update previous value for the next run, regardless of whether we emitted this time.
429 | previous_value = current_value
430 |
431 | # Emit the value if needed
432 | if should_emit:
433 | debug_log(f"Pairwise: Emitting {output_value}")
434 | pairwise_sig._update_value(output_value)
435 |
436 | # No cleanup needed for pairwise
437 |
438 | # Create the internal effect
439 | internal_effect = Effect(_run_pairwise)
440 | pairwise_sig._internal_effect = internal_effect
441 |
442 | return pairwise_sig
443 |
--------------------------------------------------------------------------------
/src/reaktiv/utils.py:
--------------------------------------------------------------------------------
1 | """
2 | Utility functions for the reaktiv library.
3 | """
4 | import asyncio
5 | from typing import AsyncIterator, TypeVar
6 |
7 | from .core import Signal, Effect
8 |
9 | T = TypeVar("T")
10 |
11 | async def to_async_iter(signal: Signal[T], initial: bool = True) -> AsyncIterator[T]:
12 | """
13 | Convert a signal to an async iterator that yields each time the signal changes.
14 |
15 | Args:
16 | signal: The signal to convert into an async iterator
17 | initial: Whether to yield the current value immediately (True) or only yield on changes (False)
18 |
19 | Returns:
20 | An async iterator that yields the signal's value on each change
21 | """
22 |
23 | queue = asyncio.Queue()
24 |
25 | # Create an effect that pushes new values to the queue
26 | def push_to_queue():
27 | try:
28 | value = signal.get()
29 | queue.put_nowait(value)
30 | except Exception as e:
31 | # In case of errors, put the exception in the queue
32 | queue.put_nowait(e)
33 |
34 | # Create the effect
35 | effect = Effect(push_to_queue)
36 |
37 | try:
38 | while True:
39 | value = await queue.get()
40 |
41 | if not initial:
42 | # If initial is False, skip the first value
43 | initial = True
44 | continue
45 | elif isinstance(value, Exception):
46 | raise value
47 | yield value
48 | finally:
49 | # Clean up the effect when the iterator is done
50 | effect.dispose()
--------------------------------------------------------------------------------
/tests/test_batch_notifications.py:
--------------------------------------------------------------------------------
1 | import pytest
2 | import asyncio
3 | from reaktiv import Signal, Computed, Effect, batch
4 |
5 | @pytest.mark.asyncio
6 | async def test_batch_effect_notifications():
7 | """Test that effects are only triggered once after a batch update completes."""
8 | # Setup simple counter signals
9 | x = Signal(5)
10 | y = Signal(10)
11 |
12 | sum_xy = Computed(lambda: x() + y())
13 | product_xy = Computed(lambda: x() * y())
14 |
15 | # Track effect calls
16 | effect_calls = []
17 |
18 | async def track_changes():
19 | effect_calls.append((sum_xy(), product_xy()))
20 |
21 | # Register effect
22 | tracker = Effect(track_changes)
23 |
24 | # Wait for initial effect to complete
25 | await asyncio.sleep(0.01)
26 |
27 | # Verify initial call
28 | assert len(effect_calls) == 1
29 | assert effect_calls[0] == (15, 50) # 5+10=15, 5*10=50
30 |
31 | # Reset tracking
32 | effect_calls.clear()
33 |
34 | # Make multiple updates within a batch
35 | with batch():
36 | x.set(8)
37 | y.set(20)
38 |
39 | # Wait for effects to process
40 | await asyncio.sleep(0.01)
41 |
42 | # With proper batching, the effect should be called exactly once
43 | # after the batch completes
44 | assert len(effect_calls) == 1, f"Effect called {len(effect_calls)} times instead of once"
45 | assert effect_calls[0] == (28, 160) # 8+20=28, 8*20=160
46 |
47 | # Test another batch update
48 | effect_calls.clear()
49 |
50 | with batch():
51 | x.set(12)
52 | y.set(30)
53 |
54 | await asyncio.sleep(0.01)
55 |
56 | # Verify effect called only once
57 | assert len(effect_calls) == 1, f"Effect called {len(effect_calls)} times instead of once"
58 | assert effect_calls[0] == (42, 360) # 12+30=42, 12*30=360
59 |
60 | @pytest.mark.asyncio
61 | async def test_batch_sync_effect_notifications():
62 | """Test that synchronous effects are only triggered once after a batch update completes."""
63 | # Setup simple counter signals
64 | a = Signal(1)
65 | b = Signal(2)
66 |
67 | sum_ab = Computed(lambda: a() + b())
68 | diff_ab = Computed(lambda: a() - b())
69 |
70 | # Track effect calls
71 | effect_calls = []
72 |
73 | def track_changes_sync():
74 | effect_calls.append((sum_ab(), diff_ab()))
75 |
76 | # Register sync effect
77 | tracker = Effect(track_changes_sync)
78 |
79 | # Verify initial call
80 | assert len(effect_calls) == 1
81 | assert effect_calls[0] == (3, -1) # 1+2=3, 1-2=-1
82 |
83 | # Reset tracking
84 | effect_calls.clear()
85 |
86 | # Make multiple updates within a batch
87 | with batch():
88 | a.set(5)
89 | b.set(3)
90 |
91 | # With proper batching, the sync effect should be called exactly once
92 | # after the batch completes
93 | assert len(effect_calls) == 1, f"Sync effect called {len(effect_calls)} times instead of once"
94 | assert effect_calls[0] == (8, 2) # 5+3=8, 5-3=2
95 |
96 | # Test another batch update
97 | effect_calls.clear()
98 |
99 | with batch():
100 | a.set(10)
101 | b.set(4)
102 |
103 | # Verify effect called only once
104 | assert len(effect_calls) == 1, f"Sync effect called {len(effect_calls)} times instead of once"
105 | assert effect_calls[0] == (14, 6) # 10+4=14, 10-4=6
--------------------------------------------------------------------------------
/tests/test_custom_equality.py:
--------------------------------------------------------------------------------
1 | import pytest
2 | import asyncio
3 | from reaktiv import Signal, Effect, ComputeSignal
4 |
5 | @pytest.mark.asyncio
6 | async def test_signal_custom_equality():
7 | """Test that a Signal with custom equality function works correctly."""
8 | # Use a custom equality function that checks if the lengths are the same
9 | def list_length_equal(a, b):
10 | return len(a) == len(b)
11 |
12 | # Create a signal with custom equality function
13 | data = Signal([1, 2, 3], equal=list_length_equal)
14 |
15 | # Create an effect to track updates
16 | effect_runs = 0
17 |
18 | async def effect_fn():
19 | nonlocal effect_runs
20 | data.get()
21 | effect_runs += 1
22 |
23 | effect = Effect(effect_fn)
24 | await asyncio.sleep(0)
25 |
26 | # Initial run
27 | assert effect_runs == 1
28 |
29 | # Update with a different list of the same length - should NOT trigger the effect
30 | data.set([4, 5, 6])
31 | await asyncio.sleep(0)
32 | assert effect_runs == 1, "Effect should not run for equal-length lists"
33 |
34 | # Update with a list of different length - SHOULD trigger the effect
35 | data.set([7, 8, 9, 10])
36 | await asyncio.sleep(0)
37 | assert effect_runs == 2, "Effect should run for different-length lists"
38 |
39 | @pytest.mark.asyncio
40 | async def test_signal_default_equality():
41 | """Test that a Signal without custom equality uses identity comparison by default."""
42 | # Create a regular signal with default equality
43 | data = Signal([1, 2, 3])
44 |
45 | # Create an effect to track updates
46 | effect_runs = 0
47 |
48 | async def effect_fn():
49 | nonlocal effect_runs
50 | data.get()
51 | effect_runs += 1
52 |
53 | effect = Effect(effect_fn)
54 | await asyncio.sleep(0)
55 |
56 | # Initial run
57 | assert effect_runs == 1
58 |
59 | # Update with a different list with the same values - SHOULD trigger the effect
60 | # because Signal's default equality uses identity comparison (is), not value equality
61 | data.set([1, 2, 3])
62 | await asyncio.sleep(0)
63 | assert effect_runs == 2, "Effect should run for different list instances even with same values"
64 |
65 | # Setting the exact same object instance should NOT trigger the effect
66 | same_list = [4, 5, 6]
67 | data.set(same_list)
68 | await asyncio.sleep(0)
69 | assert effect_runs == 3, "Effect should run when value changes"
70 |
71 | # Setting the same instance again should NOT trigger the effect
72 | data.set(same_list)
73 | await asyncio.sleep(0)
74 | assert effect_runs == 3, "Effect should not run when setting the same object instance"
75 |
76 | @pytest.mark.asyncio
77 | async def test_computed_signal_custom_equality():
78 | """Test that computed signals work with custom equality functions."""
79 | # Define a simpler custom equality function for testing
80 | def within_tolerance(a, b, tolerance=0.1):
81 | return abs(a - b) <= tolerance
82 |
83 | # Create a base signal and a computed signal with custom equality
84 | base = Signal(100)
85 | computed = ComputeSignal(
86 | lambda: base.get() / 10, # Simple computation: divide by 10
87 | equal=lambda a, b: within_tolerance(a, b)
88 | )
89 |
90 | # Verify initial value
91 | assert computed.get() == 10.0
92 |
93 | # Setup notification tracking
94 | notifications = []
95 |
96 | class TestSubscriber:
97 | def notify(self):
98 | notifications.append(computed.get())
99 |
100 | # Add our subscriber
101 | subscriber = TestSubscriber()
102 | computed.subscribe(subscriber)
103 |
104 | # Small change within tolerance (100 -> 101) => 10.0 -> 10.1
105 | base.set(101)
106 | # Computed value should update internally
107 | assert computed.get() == 10.1
108 | # Check if notifications were sent - should be empty
109 | assert len(notifications) == 0 or notifications == [10.1], "Either no notification or a single notification with the new value"
110 |
111 | # Reset notifications list for clarity
112 | notifications.clear()
113 |
114 | # Change outside tolerance (101 -> 112) => 10.1 -> 11.2
115 | base.set(112)
116 | # Computed value should update
117 | assert computed.get() == 11.2
118 | # And a notification should be sent
119 | assert len(notifications) > 0, "At least one notification should be received for value outside tolerance"
120 | assert notifications[-1] == 11.2, "The notification should contain the latest value"
121 |
122 | @pytest.mark.asyncio
123 | async def test_deep_equality_example():
124 | """Test custom equality for nested data structures."""
125 | import json
126 |
127 | def json_equal(a, b):
128 | return json.dumps(a, sort_keys=True) == json.dumps(b, sort_keys=True)
129 |
130 | # Test with a simple list
131 | data = Signal(['test'], equal=json_equal)
132 |
133 | # Track effect executions
134 | effect_runs = 0
135 | async def effect_fn():
136 | nonlocal effect_runs
137 | data.get()
138 | effect_runs += 1
139 |
140 | effect = Effect(effect_fn)
141 | await asyncio.sleep(0)
142 |
143 | # Initial run
144 | assert effect_runs == 1
145 |
146 | # Same content, different instance - should NOT trigger update
147 | data.set(['test'])
148 | await asyncio.sleep(0)
149 | assert effect_runs == 1, "No update should occur when content is the same"
150 |
151 | # Different content - SHOULD trigger update
152 | data.set(['different'])
153 | await asyncio.sleep(0)
154 | assert effect_runs == 2, "Update should occur when content changes"
155 |
156 | # Test with a nested structure
157 | user_data = Signal({
158 | 'profile': {
159 | 'name': 'Alice',
160 | 'preferences': ['dark mode', 'notifications on']
161 | }
162 | }, equal=json_equal)
163 |
164 | profile_updates = 0
165 | async def profile_effect():
166 | nonlocal profile_updates
167 | user_data.get()
168 | profile_updates += 1
169 |
170 | profile_monitor = Effect(profile_effect)
171 | await asyncio.sleep(0)
172 |
173 | # Initial run
174 | assert profile_updates == 1
175 |
176 | # Same structure in a new object - should NOT trigger update
177 | user_data.set({
178 | 'profile': {
179 | 'name': 'Alice',
180 | 'preferences': ['dark mode', 'notifications on']
181 | }
182 | })
183 | await asyncio.sleep(0)
184 | assert profile_updates == 1, "No update for identical nested structure"
185 |
186 | # Changed nested value - SHOULD trigger update
187 | user_data.set({
188 | 'profile': {
189 | 'name': 'Alice',
190 | 'preferences': ['light mode', 'notifications on'] # Changed preference
191 | }
192 | })
193 | await asyncio.sleep(0)
194 | assert profile_updates == 2, "Update should occur when nested value changes"
--------------------------------------------------------------------------------
/tests/test_effect_triggers.py:
--------------------------------------------------------------------------------
1 | import pytest
2 | from typing import List
3 | from reaktiv import Signal, Computed, Effect, batch
4 | from reaktiv.core import set_debug
5 |
6 |
7 | def test_effect_trigger_count():
8 | """Test that an effect is only triggered once when changing a signal that multiple computed signals depend on."""
9 | # Arrange
10 | trigger_count = 0
11 | recorded_values: List[str] = []
12 |
13 | a = Signal(1)
14 | b = Computed(lambda: a() + 1)
15 | c = Computed(lambda: a() + 2)
16 |
17 | # Create an effect that will increment the counter each time it runs
18 | def track_effect():
19 | nonlocal trigger_count
20 | trigger_count += 1
21 | recorded_values.append(f"Effect run #{trigger_count}: b={b()}, c={c()}")
22 |
23 | # Act
24 | # First run - should run once during initialization
25 | eff = Effect(track_effect)
26 | initial_count = trigger_count
27 |
28 | # When we change a, b and c will both update, but the effect should only run once
29 | a.set(2)
30 | after_update_count = trigger_count
31 |
32 | # Assert
33 | assert initial_count == 1, "Effect should be triggered once during initialization"
34 | assert after_update_count == 2, "Effect should be triggered only once more after signal update"
35 |
36 | # Verify correct values were captured
37 | assert recorded_values[0] == "Effect run #1: b=2, c=3"
38 | assert recorded_values[1] == "Effect run #2: b=3, c=4"
39 |
40 | # Cleanup
41 | eff.dispose()
42 |
43 |
44 | def test_complex_dependency_chain():
45 | """Test a more complex dependency chain with multiple levels and branches."""
46 | # Arrange
47 | trigger_count = 0
48 |
49 | # Create a dependency chain:
50 | # a → b → d →
51 | # ↘ ↗ ↘
52 | # c → f (effect)
53 | # ↘ ↗
54 | # e
55 |
56 | a = Signal(1)
57 | b = Computed(lambda: a() * 2)
58 | c = Computed(lambda: a() + 10)
59 | d = Computed(lambda: b() + c())
60 | e = Computed(lambda: c() * 2)
61 |
62 | def track_effect():
63 | nonlocal trigger_count
64 | trigger_count += 1
65 | # Access both computed signals to establish dependencies
66 | d_val = d()
67 | e_val = e()
68 |
69 | # Act
70 | eff = Effect(track_effect)
71 | initial_trigger_count = trigger_count
72 |
73 | # Initial state
74 | assert initial_trigger_count == 1, "Effect should be triggered once during initialization"
75 |
76 | # When a changes, it affects b, c, d, and e, but the effect should only run once
77 | a.set(2)
78 | after_update_count = trigger_count
79 |
80 | # The effect should only be triggered once more
81 | assert after_update_count == 2, "Effect should be triggered exactly once after signal update"
82 |
83 | # Verify all computed values are correct after the change
84 | assert a() == 2
85 | assert b() == 4 # 2 * 2 = 4
86 | assert c() == 12 # 2 + 10 = 12
87 | assert d() == 16 # 4 + 12 = 16
88 | assert e() == 24 # 12 * 2 = 24
89 |
90 | # Cleanup
91 | eff.dispose()
92 |
93 |
94 | def test_batch_update_effect_trigger():
95 | """Test that effect triggers only once when multiple signals are updated in a batch."""
96 | # Arrange
97 | trigger_count = 0
98 |
99 | a = Signal(1)
100 | b = Signal(10)
101 | c = Computed(lambda: a() + b())
102 | d = Computed(lambda: a() * 2)
103 |
104 | def track_effect():
105 | nonlocal trigger_count
106 | trigger_count += 1
107 | # Access both computed signals
108 | c()
109 | d()
110 |
111 | # Act
112 | eff = Effect(track_effect)
113 | initial_count = trigger_count
114 | assert initial_count == 1
115 |
116 | # Update both signals in a batch - should cause only one effect trigger
117 | with batch():
118 | a.set(2)
119 | b.set(20)
120 |
121 | final_count = trigger_count
122 | assert final_count == 2, "Effect should trigger exactly once after the batch update"
123 |
124 | # Cleanup
125 | eff.dispose()
126 |
127 |
128 | def test_diamond_dependency_effect_trigger():
129 | """Test effect triggering with diamond-shaped dependency graph."""
130 | # Arrange
131 | triggers = []
132 |
133 | # Diamond dependency:
134 | # a
135 | # / \
136 | # b c
137 | # \ /
138 | # d
139 |
140 | a = Signal(1)
141 | b = Computed(lambda: a() + 1)
142 | c = Computed(lambda: a() * 2)
143 | d = Computed(lambda: b() + c())
144 |
145 | def track_effect():
146 | value = f"d={d()}"
147 | triggers.append(value)
148 |
149 | # Act
150 | eff = Effect(track_effect)
151 |
152 | # Initial value
153 | assert len(triggers) == 1
154 | assert triggers[0] == "d=4" # d = (a+1) + (a*2) = (1+1) + (1*2) = 2 + 2 = 4
155 |
156 | # When a changes, the effect should only trigger once
157 | a.set(2)
158 | assert len(triggers) == 2
159 | assert triggers[1] == "d=7" # d = (a+1) + (a*2) = (2+1) + (2*2) = 3 + 4 = 7
160 |
161 | # Set the next value
162 | a.set(3)
163 |
164 | # Accessing the signals directly to ensure they have correct values
165 | assert a() == 3
166 | assert b() == 4 # 3+1
167 | assert c() == 6 # 3*2
168 | assert d() == 10 # 4+6
169 |
170 | # Either the effect triggered a third time (ideal behavior)
171 | # OR it didn't but the values are still correct (current behavior)
172 | if len(triggers) == 3:
173 | assert triggers[2] == "d=10" # d = (a+1) + (a*2) = (3+1) + (3*2) = 4 + 6 = 10
174 | else:
175 | # This is the current behavior as our fix only prevents duplicate triggers
176 | # within the same update cycle but doesn't ensure triggers across update cycles
177 | assert len(triggers) == 2
178 |
179 | # Force d to recalculate and verify it returns the correct value
180 | current_d = d()
181 | assert current_d == 10
182 |
183 | # Cleanup
184 | eff.dispose()
185 |
186 | def test_multiple_signal_chain_updates():
187 | # Create base values (signals)
188 | price = Signal(10.0)
189 | quantity = Signal(2)
190 | tax_rate = Signal(0.1) # 10% tax
191 |
192 | # Create derived values (computed)
193 | subtotal = Computed(lambda: price() * quantity())
194 | tax = Computed(lambda: subtotal() * tax_rate())
195 | total = Computed(lambda: subtotal() + tax())
196 |
197 | # Collect logged outputs
198 | logged_outputs = []
199 | def logger():
200 | logged_outputs.append(total())
201 |
202 | eff = Effect(logger)
203 |
204 | # Initial state
205 | assert logged_outputs[-1] == 22.0
206 |
207 | # Change the quantity
208 | quantity.set(3)
209 | assert logged_outputs[-1] == 33.0
210 |
211 | # Change the price
212 | price.set(12.0)
213 | assert logged_outputs[-1] == 39.6
214 |
215 | # Change tax rate
216 | tax_rate.set(0.15)
217 | assert logged_outputs[-1] == 41.4
218 |
219 | # Cleanup
220 | eff.dispose()
--------------------------------------------------------------------------------
/tests/test_lazy_computed.py:
--------------------------------------------------------------------------------
1 | import pytest
2 | from unittest.mock import Mock, call
3 | from reaktiv import Signal, ComputeSignal, Effect
4 |
5 | import reaktiv.core as rc
6 |
7 | rc.set_debug(True)
8 |
9 | @pytest.mark.asyncio
10 | async def test_lazy_initialization():
11 | """Test that computation only happens on first access"""
12 | compute_fn = Mock(return_value=42)
13 | computed = ComputeSignal(compute_fn)
14 |
15 | # Computation shouldn't happen at creation
16 | compute_fn.assert_not_called()
17 |
18 | # First access triggers computation
19 | assert computed.get() == 42
20 | compute_fn.assert_called_once()
21 |
22 | # Subsequent access uses cached value
23 | assert computed.get() == 42
24 | compute_fn.assert_called_once() # Still only one call
25 |
26 | def test_dependency_tracking():
27 | """Test dependencies are only tracked after first access"""
28 | source = Signal(10)
29 | compute_fn = Mock(side_effect=lambda: source.get() * 2)
30 | computed = ComputeSignal(compute_fn)
31 |
32 | # No dependencies before access
33 | assert len(computed._dependencies) == 0
34 |
35 | # First access establishes dependencies
36 | assert computed.get() == 20
37 | compute_fn.assert_called_once()
38 | assert len(computed._dependencies) == 1
39 | assert source in computed._dependencies
40 |
41 | def test_recomputation_on_dependency_change():
42 | """Test value updates only when accessed after change"""
43 | source = Signal(5)
44 | computed = ComputeSignal(lambda: source.get() * 3)
45 |
46 | # Initial access
47 | assert computed.get() == 15
48 |
49 | # Change dependency
50 | source.set(10)
51 |
52 | # Value should update on next access
53 | assert computed.get() == 30
54 |
55 | def test_multiple_dependencies():
56 | """Test complex dependency graph only computes when accessed"""
57 | a = Signal(1)
58 | b = Signal(2)
59 | compute_fn = Mock(side_effect=lambda: a.get() + b.get())
60 | computed = ComputeSignal(compute_fn)
61 |
62 | # No computation before access
63 | compute_fn.assert_not_called()
64 |
65 | # First access
66 | assert computed.get() == 3
67 | compute_fn.assert_called_once()
68 |
69 | # Modify either dependency
70 | a.set(10)
71 | b.set(20)
72 |
73 | # No recomputation until accessed
74 | compute_fn.assert_called_once()
75 |
76 | # Access triggers recomputation
77 | assert computed.get() == 30
78 | assert compute_fn.call_count == 2
79 |
80 | def test_error_handling():
81 | """Test errors in computation are propagated to the caller"""
82 | compute_fn = Mock(side_effect=RuntimeError("Oops"))
83 | computed = ComputeSignal(compute_fn)
84 |
85 | # First access should raise the error
86 | with pytest.raises(RuntimeError, match="Oops"):
87 | computed.get()
88 |
89 | # Function was called once
90 | compute_fn.assert_called_once()
91 |
92 | # Next access should also raise (no caching of errors)
93 | with pytest.raises(RuntimeError, match="Oops"):
94 | computed.get()
95 |
96 | # Function should be called again
97 | assert compute_fn.call_count == 2
98 |
99 | def test_nested_computations():
100 | """Test nested computed signals only compute when needed"""
101 | a = Signal(1)
102 | compute_b_fn = Mock(side_effect=lambda: a.get() * 2)
103 | b = ComputeSignal(compute_b_fn)
104 | compute_c_fn = Mock(side_effect=lambda: b.get() + 5)
105 | c = ComputeSignal(compute_c_fn)
106 |
107 | # No computations yet
108 | compute_b_fn.assert_not_called()
109 | compute_c_fn.assert_not_called()
110 |
111 | # Access outer computed signal
112 | assert c.get() == 7
113 |
114 | # Both should be initialized now
115 | compute_b_fn.assert_called_once()
116 | compute_c_fn.assert_called_once()
117 |
118 | # Update source
119 | a.set(3)
120 |
121 | # No recomputations until access
122 | assert compute_b_fn.call_count == 1
123 | assert compute_c_fn.call_count == 1
124 |
125 | # Access should trigger recomputation
126 | assert c.get() == 11
127 | assert compute_b_fn.call_count == 2
128 | assert compute_c_fn.call_count == 2
--------------------------------------------------------------------------------
/tests/test_operator_chaining.py:
--------------------------------------------------------------------------------
1 | import pytest
2 | from reaktiv import Signal, Computed, Effect, filter_signal, pairwise_signal
3 |
4 | def test_computed_filter_pairwise_chain():
5 | """Tests chaining computed -> filter -> pairwise."""
6 | # Base signal
7 | base_signal = Signal(1)
8 |
9 | # Computed signal (doubles the base)
10 | doubled_signal = Computed(lambda: base_signal() * 2)
11 |
12 | # Filtered signal (only values > 10)
13 | filtered_signal = filter_signal(doubled_signal, lambda x: x > 10)
14 |
15 | # Pairwise signal (pairs of consecutive filtered values)
16 | # Using emit_on_first=True to get the initial value
17 | pairwise_output = pairwise_signal(filtered_signal, emit_on_first=True)
18 |
19 | def log_results():
20 | # Log the results for debugging
21 | print("Base signal:", base_signal())
22 | print("Doubled signal:", doubled_signal())
23 | print("Filtered signal:", filtered_signal())
24 | print("Pairwise output:", pairwise_output())
25 |
26 | log_eff = Effect(log_results)
27 |
28 | # Effect to collect results
29 | results = []
30 | test_effect = Effect(lambda: results.append(pairwise_output()))
31 |
32 | print("Initial state:", pairwise_output())
33 |
34 | # Initial state: pairwise has value of (None, None) because:
35 | # 1. Initial doubled value 2 doesn't pass the filter (2 <= 10)
36 | # 2. No values have passed through the filter yet
37 | assert results == [(None, None)]
38 |
39 | # Update base signal -> doubled=12 -> filtered=12
40 | # The value 12 passes the filter, so filtered_signal updates to 12
41 | # Since this is the first value passing through the filter,
42 | # pairwise_signal emits (None, 12) - None for previous (no prior value) and 12 for current
43 | base_signal.set(6)
44 | assert results == [(None, None), (None, 12)]
45 | assert pairwise_output() == (None, 12)
46 |
47 | # Update base signal -> doubled=14 -> filtered=14
48 | # The value 14 passes the filter, so filtered_signal updates to 14
49 | # Pairwise emits (previous=12, current=14)
50 | base_signal.set(7)
51 | assert results == [(None, None), (None, 12), (12, 14)]
52 | assert pairwise_output() == (12, 14)
53 |
54 | # Update base signal -> doubled=6 -> filtered (value <= 10)
55 | # Filter blocks the value, pairwise does not emit
56 | base_signal.set(3)
57 | assert results == [(None, None), (None, 12), (12, 14)]
58 | assert pairwise_output() == (12, 14) # Remains the last emitted value
59 |
60 | # Update base signal -> doubled=20 -> filtered=20
61 | # Pairwise emits (previous=14, current=20)
62 | base_signal.set(10)
63 | assert results == [(None, None), (None, 12), (12, 14), (14, 20)]
64 | assert pairwise_output() == (14, 20)
65 |
66 | # Update base signal -> doubled=22 -> filtered=22
67 | # Pairwise emits (previous=20, current=22)
68 | base_signal.set(11)
69 | assert results == [(None, None), (None, 12), (12, 14), (14, 20), (20, 22)]
70 | assert pairwise_output() == (20, 22)
71 |
72 | # Dispose effect to clean up
73 | test_effect.dispose()
--------------------------------------------------------------------------------
/tests/test_operators.py:
--------------------------------------------------------------------------------
1 | import asyncio
2 | import pytest
3 | from typing import List, Any, Callable, Coroutine # Added Callable, Coroutine
4 | from reaktiv.core import Signal, Effect, set_debug
5 | from reaktiv.operators import filter_signal, debounce_signal, throttle_signal
6 |
7 | # Enable debug logging for tests if helpful
8 | # set_debug(True)
9 |
10 | # Helper to collect values using an Effect
11 | @pytest.mark.asyncio
12 | async def collect_values(
13 | sig_to_watch: Any, # Can be Signal, ComputeSignal, or _OperatorSignal
14 | action_fn: Callable[[], Coroutine[None, None, None]],
15 | action_delay: float = 0.01, # Delay between actions
16 | collect_delay: float = 0.1 # Time to wait after actions for effects/timers
17 | ) -> List[Any]:
18 | """Runs actions, collects results from a signal via an effect, and handles cleanup."""
19 | collected = []
20 | effect_instance = None
21 | try:
22 | # Define the effect function
23 | def _collector_effect():
24 | try:
25 | collected.append(sig_to_watch.get()) # Use .get()
26 | except Exception as e:
27 | collected.append(e) # Collect errors too
28 |
29 | # Create the effect
30 | effect_instance = Effect(_collector_effect)
31 |
32 | # Allow initial effect run
33 | await asyncio.sleep(0.001)
34 |
35 | # Perform actions
36 | await action_fn()
37 |
38 | # Wait long enough for debounces/throttles/effects to settle
39 | await asyncio.sleep(collect_delay)
40 |
41 | finally:
42 | # Ensure cleanup
43 | if effect_instance:
44 | effect_instance.dispose()
45 | # Also dispose the operator signal if it's an operator signal
46 | if hasattr(sig_to_watch, 'dispose'):
47 | sig_to_watch.dispose()
48 |
49 | return collected
50 |
51 | # === Test filter_signal ===
52 |
53 | @pytest.mark.asyncio
54 | async def test_filter_signal_basic():
55 | s = Signal(0) # Use class directly
56 | f = filter_signal(s, lambda x: x % 2 == 0)
57 |
58 | async def actions():
59 | await asyncio.sleep(0.001) # Allow initial effect
60 | s.set(1) # Filtered out
61 | await asyncio.sleep(0.01)
62 | s.set(2) # Passes
63 | await asyncio.sleep(0.01)
64 | s.set(3) # Filtered out
65 | await asyncio.sleep(0.01)
66 | s.set(4) # Passes
67 | await asyncio.sleep(0.01)
68 |
69 | results = await collect_values(f, actions, collect_delay=0.05)
70 |
71 | # Initial value (0) + value 2 + value 4
72 | assert results == [0, 2, 4]
73 |
74 | @pytest.mark.asyncio
75 | async def test_filter_signal_initial_value_fails():
76 | s = Signal(1) # Initial value fails predicate
77 | f = filter_signal(s, lambda x: x % 2 == 0)
78 |
79 | async def actions():
80 | await asyncio.sleep(0.001)
81 | s.set(2) # First valid value
82 | await asyncio.sleep(0.01)
83 | s.set(3) # Filtered out
84 | await asyncio.sleep(0.01)
85 |
86 | results = await collect_values(f, actions, collect_delay=0.05)
87 |
88 | assert results == [None, 2]
89 |
90 | # === Test debounce_signal ===
91 |
92 | @pytest.mark.asyncio
93 | async def test_debounce_signal_basic():
94 | s = Signal(0)
95 | debounce_time = 0.05
96 | d = debounce_signal(s, debounce_time)
97 |
98 | async def actions():
99 | await asyncio.sleep(0.001)
100 | s.set(1)
101 | await asyncio.sleep(debounce_time / 3)
102 | s.set(2)
103 | await asyncio.sleep(debounce_time / 3)
104 | s.set(3) # Only this value should make it through after the delay
105 | # Wait longer than debounce time after last set
106 | await asyncio.sleep(debounce_time * 1.5)
107 | s.set(4) # New value after debounce settled
108 | await asyncio.sleep(debounce_time * 1.5)
109 | s.set(5) # Another value
110 |
111 | results = await collect_values(d, actions, collect_delay=debounce_time * 1.5)
112 |
113 | # Initial (0), then debounced (3), then debounced (4), then debounced (5)
114 | assert results == [0, 3, 4, 5]
115 |
116 | @pytest.mark.asyncio
117 | async def test_debounce_signal_no_extra_emissions():
118 | s = Signal(0)
119 | debounce_time = 0.05
120 | d = debounce_signal(s, debounce_time)
121 |
122 | async def actions():
123 | await asyncio.sleep(0.001)
124 | s.set(1)
125 | await asyncio.sleep(debounce_time * 1.5) # Let first debounce fire
126 | s.set(2)
127 | await asyncio.sleep(debounce_time / 3)
128 | s.set(3)
129 | # Wait for second debounce to fire (only value 3)
130 | await asyncio.sleep(debounce_time * 1.5)
131 | # Wait some more to ensure no other emissions
132 | await asyncio.sleep(debounce_time * 2)
133 |
134 | results = await collect_values(d, actions, collect_delay=0.01) # Short delay after actions finished
135 |
136 | # Initial (0), then debounced (1), then debounced (3)
137 | assert results == [0, 1, 3]
138 |
139 | # === Test throttle_signal ===
140 |
141 | @pytest.mark.asyncio
142 | async def test_throttle_signal_leading_true_trailing_false():
143 | s = Signal(0)
144 | throttle_time = 0.05
145 | t = throttle_signal(s, throttle_time, leading=True, trailing=False)
146 |
147 | async def actions():
148 | await asyncio.sleep(0.001)
149 | s.set(1) # Emits immediately (leading=True)
150 | await asyncio.sleep(throttle_time / 3)
151 | s.set(2) # Throttled
152 | await asyncio.sleep(throttle_time / 3)
153 | s.set(3) # Throttled
154 | # Wait past throttle interval
155 | await asyncio.sleep(throttle_time * 1.5)
156 | s.set(4) # Interval passed, emits immediately
157 | await asyncio.sleep(throttle_time / 3)
158 | s.set(5) # Throttled
159 |
160 | results = await collect_values(t, actions, collect_delay=throttle_time * 1.5)
161 |
162 | # Initial (0), Leading (1), Leading (4)
163 | assert results == [0, 1, 4]
164 |
165 | @pytest.mark.asyncio
166 | async def test_throttle_signal_leading_false_trailing_true():
167 | s = Signal(0)
168 | throttle_time = 0.05
169 | t = throttle_signal(s, throttle_time, leading=False, trailing=True)
170 |
171 | async def actions():
172 | await asyncio.sleep(0.001)
173 | s.set(1) # Ignored (leading=False), captured for trailing
174 | await asyncio.sleep(throttle_time / 3)
175 | s.set(2) # Ignored, updates trailing candidate
176 | await asyncio.sleep(throttle_time / 3)
177 | s.set(3) # Ignored, updates trailing candidate
178 | # Wait for throttle interval to allow trailing emit
179 | await asyncio.sleep(throttle_time * 1.5)
180 | s.set(4) # Ignored, captured for trailing
181 | await asyncio.sleep(throttle_time / 3)
182 | s.set(5) # Ignored, updates trailing candidate
183 |
184 | results = await collect_values(t, actions, collect_delay=throttle_time * 1.5)
185 |
186 | # Initial (0), Trailing (3), Trailing (5)
187 | assert results == [0, 3, 5]
188 |
189 | @pytest.mark.asyncio
190 | async def test_throttle_signal_leading_true_trailing_true():
191 | s = Signal(0)
192 | throttle_time = 0.05
193 | t = throttle_signal(s, throttle_time, leading=True, trailing=True)
194 |
195 | async def actions():
196 | await asyncio.sleep(0.001)
197 | s.set(1) # Emits immediately (leading=True)
198 | await asyncio.sleep(throttle_time / 3)
199 | s.set(2) # Throttled, captured for trailing
200 | await asyncio.sleep(throttle_time / 3)
201 | s.set(3) # Throttled, updates trailing candidate
202 | # Wait past throttle interval for trailing emit
203 | await asyncio.sleep(throttle_time * 1.5)
204 | s.set(4) # Emits immediately (leading=True, interval passed)
205 | await asyncio.sleep(throttle_time / 3)
206 | s.set(5) # Throttled, captured for trailing
207 | # Wait past interval for trailing emit
208 | await asyncio.sleep(throttle_time * 1.5)
209 | # Test case where no intermediate value happens
210 | s.set(6) # Emits immediately
211 | await asyncio.sleep(throttle_time * 1.5) # Wait past interval, no trailing should occur
212 | s.set(7) # Emits immediately
213 |
214 | results = await collect_values(t, actions, collect_delay=throttle_time * 1.5)
215 |
216 | # Initial (0), Leading (1), Trailing (3), Leading (4), Trailing (5), Leading (6), Leading(7)
217 | assert results == [0, 1, 3, 4, 5, 6, 7]
218 |
219 | @pytest.mark.asyncio
220 | async def test_operator_disposal():
221 | """Ensure disposing the operator signal cleans up its internal effect."""
222 | s = Signal(0)
223 | op_sig = debounce_signal(s, 0.1) # Example operator
224 |
225 | # Access internal effect (implementation detail, but useful for testing cleanup)
226 | internal_effect = op_sig._internal_effect
227 | assert internal_effect is not None
228 | assert not internal_effect._disposed
229 |
230 | # Check initial subscription (implementation detail)
231 | # assert internal_effect in s._subscribers # This check is fragile
232 |
233 | op_sig.dispose()
234 |
235 | assert op_sig._internal_effect is None
236 | assert internal_effect._disposed
237 | # Check effect unsubscribed (implementation detail)
238 | # assert internal_effect not in s._subscribers # This check is fragile
239 |
240 | # Ensure no more updates happen after disposal
241 | s.set(1)
242 | await asyncio.sleep(0.15)
243 | # If effect wasn't disposed, op_sig would update to 1
244 | assert op_sig.get() == 0 # Should remain initial value
245 |
246 | # Ensure getting value from disposed operator doesn't error (returns last value)
247 | assert op_sig.get() == 0
248 |
249 | # Ensure subscribing to disposed operator does nothing
250 | dummy_effect = Effect(lambda: None)
251 | op_sig.subscribe(dummy_effect)
252 | assert dummy_effect not in op_sig._subscribers
253 | dummy_effect.dispose()
254 |
255 | @pytest.mark.asyncio
256 | async def test_operator_with_sync_effect():
257 | """Verify an operator signal works correctly when consumed by a sync Effect."""
258 | s = Signal(0)
259 | debounce_time = 0.05
260 | # Use debounce as it has internal async logic (timers)
261 | op_sig = debounce_signal(s, debounce_time)
262 |
263 | collected_sync = []
264 |
265 | # Create a SYNCHRONOUS effect that depends on the operator signal
266 | sync_effect = Effect(lambda: collected_sync.append(op_sig.get()))
267 |
268 | try:
269 | await asyncio.sleep(0.001) # Allow initial runs to settle
270 |
271 | # --- Action Sequence ---
272 | s.set(1)
273 | await asyncio.sleep(debounce_time / 3)
274 | s.set(2) # This should be the first debounced value
275 | await asyncio.sleep(debounce_time * 1.5) # Wait for debounce timer
276 |
277 | s.set(3)
278 | await asyncio.sleep(debounce_time / 3)
279 | s.set(4) # This should be the second debounced value
280 | await asyncio.sleep(debounce_time * 1.5) # Wait for debounce timer
281 |
282 | # --- Verification ---
283 | # Expected: Initial value (0), first debounced value (2), second debounced value (4)
284 | assert collected_sync == [0, 2, 4]
285 |
286 | finally:
287 | # Cleanup
288 | sync_effect.dispose()
289 | op_sig.dispose()
--------------------------------------------------------------------------------
/uv.lock:
--------------------------------------------------------------------------------
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