├── .appveyor.yml ├── .gitignore ├── .travis.yml ├── Cargo.toml ├── LICENSE-APACHE ├── LICENSE-MIT ├── README.md └── src └── lib.rs /.appveyor.yml: -------------------------------------------------------------------------------- 1 | os: Visual Studio 2015 2 | environment: 3 | matrix: 4 | - channel: stable 5 | target: x86_64-pc-windows-msvc 6 | - channel: beta 7 | target: x86_64-pc-windows-msvc 8 | - channel: nightly 9 | target: x86_64-pc-windows-msvc 10 | - channel: stable 11 | target: x86_64-pc-windows-gnu 12 | - channel: beta 13 | target: x86_64-pc-windows-gnu 14 | - channel: nightly 15 | target: x86_64-pc-windows-gnu 16 | matrix: 17 | allow_failures: 18 | - channel: nightly 19 | install: 20 | - appveyor DownloadFile https://win.rustup.rs/ -FileName rustup-init.exe 21 | - rustup-init -yv --default-toolchain %channel% --default-host %target% 22 | - set PATH=%PATH%;%USERPROFILE%\.cargo\bin 23 | - rustc -vV 24 | - cargo -vV 25 | build: false 26 | test_script: 27 | - cargo test --verbose %cargoflags% 28 | -------------------------------------------------------------------------------- /.gitignore: -------------------------------------------------------------------------------- 1 | target 2 | Cargo.lock 3 | -------------------------------------------------------------------------------- /.travis.yml: -------------------------------------------------------------------------------- 1 | sudo: false 2 | language: rust 3 | cache: cargo 4 | rust: 5 | - stable 6 | - beta 7 | - nightly 8 | matrix: 9 | allow_failures: 10 | - rust: nightly 11 | -------------------------------------------------------------------------------- /Cargo.toml: -------------------------------------------------------------------------------- 1 | [package] 2 | name = "features" 3 | version = "0.10.0" 4 | authors = ["Fletcher Nichol "] 5 | license = "MIT/Apache-2.0" 6 | readme = "README.md" 7 | repository = "https://github.com/fnichol/features-rs" 8 | documentation = "https://docs.rs/features" 9 | keywords = ["feature", "toggle", "flag"] 10 | categories = ["config", "development-tools"] 11 | description = """ 12 | A macro to generate runtime feature toggles. 13 | """ 14 | 15 | [dependencies] 16 | bitflags = "^1.0" 17 | -------------------------------------------------------------------------------- /LICENSE-APACHE: -------------------------------------------------------------------------------- 1 | Apache License 2 | Version 2.0, January 2004 3 | http://www.apache.org/licenses/ 4 | 5 | TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION 6 | 7 | 1. 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We also recommend that a 185 | file or class name and description of purpose be included on the 186 | same "printed page" as the copyright notice for easier 187 | identification within third-party archives. 188 | 189 | Copyright [yyyy] [name of copyright owner] 190 | 191 | Licensed under the Apache License, Version 2.0 (the "License"); 192 | you may not use this file except in compliance with the License. 193 | You may obtain a copy of the License at 194 | 195 | http://www.apache.org/licenses/LICENSE-2.0 196 | 197 | Unless required by applicable law or agreed to in writing, software 198 | distributed under the License is distributed on an "AS IS" BASIS, 199 | WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 200 | See the License for the specific language governing permissions and 201 | limitations under the License. 202 | -------------------------------------------------------------------------------- /LICENSE-MIT: -------------------------------------------------------------------------------- 1 | Copyright (c) 2017 Fletcher Nichol 2 | 3 | Permission is hereby granted, free of charge, to any 4 | person obtaining a copy of this software and associated 5 | documentation files (the "Software"), to deal in the 6 | Software without restriction, including without 7 | limitation the rights to use, copy, modify, merge, 8 | publish, distribute, sublicense, and/or sell copies of 9 | the Software, and to permit persons to whom the Software 10 | is furnished to do so, subject to the following 11 | conditions: 12 | 13 | The above copyright notice and this permission notice 14 | shall be included in all copies or substantial portions 15 | of the Software. 16 | 17 | THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF 18 | ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED 19 | TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A 20 | PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT 21 | SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY 22 | CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION 23 | OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR 24 | IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER 25 | DEALINGS IN THE SOFTWARE. 26 | -------------------------------------------------------------------------------- /README.md: -------------------------------------------------------------------------------- 1 | # Features 2 | 3 | [![Crate version](https://img.shields.io/crates/v/features.svg)][crate] 4 | [![Crate downloads](https://img.shields.io/crates/d/features.svg)][crate] 5 | [![Crate license](https://img.shields.io/crates/l/features.svg)][github] 6 | [![Documentation](https://img.shields.io/badge/documentation-docs.rs-df3600.svg?style=flat-square)][docs] 7 | 8 | [![AppVeyor](https://img.shields.io/appveyor/ci/fnichol/features-rs.svg)][build-windows] (Windows) 9 | [![Travis](https://img.shields.io/travis/fnichol/features-rs.svg)][build-unix] (Linux and OS X) 10 | 11 | [build-unix]: https://travis-ci.org/fnichol/features-rs 12 | [build-windows]: https://ci.appveyor.com/project/fnichol/features-rs 13 | [crate]: https://crates.io/crates/features 14 | [docs]: https://docs.rs/features 15 | [github]: https://github.com/fnichol/features-rs 16 | [lic-apachev2]: https://github.com/fnichol/features-rs/blob/master/LICENSE-APACHE 17 | [lic-mit]: https://github.com/fnichol/features-rs/blob/master/LICENSE-MIT 18 | 19 | ## About 20 | 21 | `features` is a small library that implements runtime [feature toggles][fowler_toggles] for 22 | your library or program allowing behavior to be changed on boot or dynamically at runtime using 23 | the same compiled binary artifact. This is different from cargo's [feature][cargo_feature] 24 | support which uses conditional compilation. 25 | 26 | At its core, it is a macro (`features!`) that takes a collection of feature flag names which it 27 | uses to generate a module containing a function to enable a feature toggle (`::enable()`), a 28 | function to disable a feature toggle (`::disable()`) and a function to check if a feature 29 | toggle is enabled (`::is_enabled()`). 30 | 31 | [fowler_toggles]: https://martinfowler.com/articles/feature-toggles.html 32 | [cargo_feature]: http://doc.crates.io/manifest.html#the-features-section 33 | 34 | ## Example 35 | 36 | Basic example: 37 | 38 | ```rust 39 | #[macro_use] 40 | extern crate bitflags; 41 | #[macro_use] 42 | extern crate features; 43 | 44 | features! { 45 | pub mod feature { 46 | const Alpha = 0b00000001, 47 | const Beta = 0b00000010 48 | } 49 | } 50 | 51 | fn main() { 52 | assert_eq!(false, feature::is_enabled(feature::Alpha)); 53 | assert_eq!(false, feature::is_enabled(feature::Beta)); 54 | 55 | feature::enable(feature::Beta); 56 | assert_eq!(false, feature::is_enabled(feature::Alpha)); 57 | assert_eq!(true, feature::is_enabled(feature::Beta)); 58 | } 59 | ``` 60 | 61 | Multiple feature sets: 62 | 63 | ```rust 64 | #[macro_use] 65 | extern crate bitflags; 66 | #[macro_use] 67 | extern crate features; 68 | 69 | features! { 70 | pub mod ux { 71 | const JsonOutput = 0b10000000, 72 | const VerboseOutput = 0b01000000 73 | } 74 | } 75 | 76 | features! { 77 | pub mod srv { 78 | const Http2Downloading = 0b10000000, 79 | const BitTorrentDownloading = 0b01000000 80 | } 81 | } 82 | 83 | fn main() { 84 | // Parse CLI args, environment, read config file etc... 85 | srv::enable(srv::BitTorrentDownloading); 86 | ux::enable(ux::JsonOutput); 87 | 88 | if srv::is_enabled(srv::Http2Downloading) { 89 | println!("Downloading via http2..."); 90 | } else if srv::is_enabled(srv::BitTorrentDownloading) { 91 | println!("Downloading via bit torrent..."); 92 | } else { 93 | println!("Downloading the old fashioned way..."); 94 | } 95 | 96 | if ux::is_enabled(ux::VerboseOutput) { 97 | println!("COOL"); 98 | } 99 | } 100 | ``` 101 | 102 | ## Feature Toggle References 103 | 104 | Here are some articles and projects which insipred the implementation of `features`: 105 | 106 | * [Feature Toggles](https://martinfowler.com/articles/feature-toggles.html) (Martin Fowler's 107 | blog) 108 | * [Using Feature Flags to Ship Changes with 109 | Confidence](https://blog.travis-ci.com/2014-03-04-use-feature-flags-to-ship-changes-with-confidence/) 110 | (TravisCI's blog) 111 | * [Feature Toggles are one of the worst kinds of Technical 112 | Debt](http://swreflections.blogspot.ca/2014/08/feature-toggles-are-one-of-worst-kinds.html) 113 | (excellent cautionary tale and warning) 114 | * [Feature toggle](https://en.wikipedia.org/wiki/Feature_toggle) (Wikipedia article) 115 | * [Ruby feature gem](https://github.com/mgsnova/feature) (nice prior art) 116 | 117 | ## License 118 | 119 | Features is licensed under the Apache License, Version 2.0 and the MIT license. Please read the [LICENSE-APACHE] and [LICENSE-MIT] for details 120 | 121 | [LICENSE-APACHE]: https://github.com/fnichol/features-rs/blob/master/LICENSE-MIT 122 | [LICENSE-MIT]: https://github.com/fnichol/features-rs/blob/master/MIT-MIT 123 | -------------------------------------------------------------------------------- /src/lib.rs: -------------------------------------------------------------------------------- 1 | // Copyright ⓒ 2017 Fletcher Nichol and/or applicable contributors. 2 | // 3 | // Licensed under the Apache License, Version 2.0 (see LICENSE-APACHE or 4 | // ) or the MIT license (see, at your option. This file may not be copied, modified, or 6 | // distributed except according to those terms. 7 | 8 | //! `features` is a small library that implements runtime [feature toggles][fowler_toggles] for 9 | //! your library or program allowing behavior to be changed on boot or dynamically at runtime using 10 | //! the same compiled binary artifact. This is different from cargo's [feature][cargo_feature] 11 | //! support which uses conditional compilation. 12 | //! 13 | //! At its core, it is a macro (`features!`) that takes a collection of feature flag names which it 14 | //! uses to generate a module containing a function to enable a feature toggle (`::enable()`), a 15 | //! function to disable a feature toggle (`::disable()`) and a function to check if a feature 16 | //! toggle is enabled (`::is_enabled()`). 17 | //! 18 | //! ## Example 19 | //! 20 | //! Basic example: 21 | //! 22 | //! ``` 23 | //! #[macro_use] 24 | //! extern crate bitflags; 25 | //! #[macro_use] 26 | //! extern crate features; 27 | //! 28 | //! features! { 29 | //! pub mod feature { 30 | //! const Alpha = 0b00000001, 31 | //! const Beta = 0b00000010 32 | //! } 33 | //! } 34 | //! 35 | //! fn main() { 36 | //! assert_eq!(false, feature::is_enabled(feature::Alpha)); 37 | //! assert_eq!(false, feature::is_enabled(feature::Beta)); 38 | //! 39 | //! feature::enable(feature::Beta); 40 | //! assert_eq!(false, feature::is_enabled(feature::Alpha)); 41 | //! assert_eq!(true, feature::is_enabled(feature::Beta)); 42 | //! } 43 | //! ``` 44 | //! 45 | //! Multiple feature sets: 46 | //! 47 | //! ``` 48 | //! #[macro_use] 49 | //! extern crate bitflags; 50 | //! #[macro_use] 51 | //! extern crate features; 52 | //! 53 | //! features! { 54 | //! pub mod ux { 55 | //! const JsonOutput = 0b10000000, 56 | //! const VerboseOutput = 0b01000000 57 | //! } 58 | //! } 59 | //! 60 | //! features! { 61 | //! pub mod srv { 62 | //! const Http2Downloading = 0b10000000, 63 | //! const BitTorrentDownloading = 0b01000000 64 | //! } 65 | //! } 66 | //! 67 | //! fn main() { 68 | //! // Parse CLI args, environment, read config file etc... 69 | //! srv::enable(srv::BitTorrentDownloading); 70 | //! ux::enable(ux::JsonOutput); 71 | //! 72 | //! if srv::is_enabled(srv::Http2Downloading) { 73 | //! println!("Downloading via http2..."); 74 | //! } else if srv::is_enabled(srv::BitTorrentDownloading) { 75 | //! println!("Downloading via bit torrent..."); 76 | //! } else { 77 | //! println!("Downloading the old fashioned way..."); 78 | //! } 79 | //! 80 | //! if ux::is_enabled(ux::VerboseOutput) { 81 | //! println!("COOL"); 82 | //! } 83 | //! } 84 | //! ``` 85 | //! 86 | //! ## Feature Toggle References 87 | //! 88 | //! Here are some articles and projects which insipred the implementation of `features`: 89 | //! 90 | //! * [Feature Toggles](https://martinfowler.com/articles/feature-toggles.html) (Martin Fowler's 91 | //! blog) 92 | //! * [Using Feature Flags to Ship Changes with 93 | //! Confidence](https://blog.travis-ci.com/2014-03-04-use-feature-flags-to-ship-changes-with-confidence/) 94 | //! (TravisCI's blog) 95 | //! * [Feature Toggles are one of the worst kinds of Technical 96 | //! Debt](http://swreflections.blogspot.ca/2014/08/feature-toggles-are-one-of-worst-kinds.html) 97 | //! (excellent cautionary tale and warning) 98 | //! * [Feature toggle](https://en.wikipedia.org/wiki/Feature_toggle) (Wikipedia article) 99 | //! * [Ruby feature gem](https://github.com/mgsnova/feature) (nice prior art) 100 | //! 101 | //! [fowler_toggles]: https://martinfowler.com/articles/feature-toggles.html 102 | //! [cargo_feature]: http://doc.crates.io/manifest.html#the-features-section 103 | 104 | #[cfg(test)] 105 | #[macro_use] 106 | extern crate bitflags; 107 | 108 | /// The `features!` macro generates a module to contain all feature toggling logic. 109 | /// 110 | /// # Examples 111 | /// 112 | /// Basic example: 113 | /// 114 | /// ``` 115 | /// #[macro_use] 116 | /// extern crate bitflags; 117 | /// #[macro_use] 118 | /// extern crate features; 119 | /// 120 | /// features! { 121 | /// pub mod feature { 122 | /// const Alpha = 0b00000001, 123 | /// const Beta = 0b00000010 124 | /// } 125 | /// } 126 | /// 127 | /// fn main() { 128 | /// assert_eq!(false, feature::is_enabled(feature::Alpha)); 129 | /// assert_eq!(false, feature::is_enabled(feature::Beta)); 130 | /// 131 | /// feature::enable(feature::Beta); 132 | /// assert_eq!(false, feature::is_enabled(feature::Alpha)); 133 | /// assert_eq!(true, feature::is_enabled(feature::Beta)); 134 | /// } 135 | /// ``` 136 | /// 137 | /// Multiple feature sets: 138 | /// 139 | /// ``` 140 | /// #[macro_use] 141 | /// extern crate bitflags; 142 | /// #[macro_use] 143 | /// extern crate features; 144 | /// 145 | /// features! { 146 | /// pub mod ux { 147 | /// const JsonOutput = 0b10000000, 148 | /// const VerboseOutput = 0b01000000 149 | /// } 150 | /// } 151 | /// 152 | /// features! { 153 | /// pub mod srv { 154 | /// const Http2Downloading = 0b10000000, 155 | /// const BitTorrentDownloading = 0b01000000 156 | /// } 157 | /// } 158 | /// 159 | /// fn main() { 160 | /// // Parse CLI args, environment, read config file etc... 161 | /// srv::enable(srv::BitTorrentDownloading); 162 | /// ux::enable(ux::JsonOutput); 163 | /// 164 | /// if srv::is_enabled(srv::Http2Downloading) { 165 | /// println!("Downloading via http2..."); 166 | /// } else if srv::is_enabled(srv::BitTorrentDownloading) { 167 | /// println!("Downloading via bit torrent..."); 168 | /// } else { 169 | /// println!("Downloading the old fashioned way..."); 170 | /// } 171 | /// 172 | /// if ux::is_enabled(ux::VerboseOutput) { 173 | /// println!("COOL"); 174 | /// } 175 | /// } 176 | /// ``` 177 | #[macro_export] 178 | macro_rules! features { 179 | (mod $mod_name:ident { 180 | $($(#[$flag_attr:meta])* const $flag:ident = $value:expr),+ 181 | }) => { 182 | #[allow(non_upper_case_globals)] 183 | mod $mod_name { 184 | features! { 185 | @_impl mod $mod_name { 186 | $($(#[$flag_attr])* const $flag = $value),+ 187 | } 188 | } 189 | } 190 | }; 191 | (pub mod $mod_name:ident { 192 | $($(#[$flag_attr:meta])* const $flag:ident = $value:expr),+ 193 | }) => { 194 | #[allow(non_upper_case_globals)] 195 | pub mod $mod_name { 196 | features! { 197 | @_impl mod $mod_name { 198 | $($(#[$flag_attr])* const $flag = $value),+ 199 | } 200 | } 201 | } 202 | }; 203 | (@_impl mod $mod_name:ident { 204 | $($(#[$flag_attr:meta])* const $flag:ident = $value:expr),+ 205 | }) => { 206 | use std::sync::atomic; 207 | 208 | bitflags! { 209 | pub struct Flags: usize { 210 | $( 211 | $(#[$flag_attr])* const $flag = $value; 212 | )+ 213 | } 214 | } 215 | $( 216 | pub const $flag: Flags = Flags::$flag; 217 | )+ 218 | 219 | static mut FEATURES: atomic::AtomicUsize = atomic::AtomicUsize::new(0); 220 | 221 | #[allow(dead_code)] 222 | pub fn enable(flag: Flags) { 223 | let features = unsafe { FEATURES.get_mut() }; 224 | let mut flags = Flags::from_bits_truncate(*features); 225 | flags.insert(flag); 226 | *features = flags.bits(); 227 | } 228 | 229 | #[allow(dead_code)] 230 | pub fn disable(flag: Flags) { 231 | let features = unsafe { FEATURES.get_mut() }; 232 | let mut flags = Flags::from_bits_truncate(*features); 233 | flags.remove(flag); 234 | *features = flags.bits(); 235 | } 236 | 237 | #[allow(dead_code)] 238 | pub fn is_enabled(flag: Flags) -> bool { 239 | flags().contains(flag) 240 | } 241 | 242 | #[allow(dead_code)] 243 | pub fn flags() -> Flags { 244 | unsafe { Flags::from_bits_truncate(FEATURES.load(atomic::Ordering::Relaxed)) } 245 | } 246 | }; 247 | } 248 | 249 | #[cfg(test)] 250 | mod tests { 251 | #[test] 252 | fn enabling() { 253 | features! { 254 | pub mod f { 255 | const Alpha = 0b00000001, 256 | const Beta = 0b00000010 257 | } 258 | } 259 | 260 | assert_eq!(false, f::is_enabled(f::Alpha)); 261 | assert_eq!(false, f::is_enabled(f::Beta)); 262 | 263 | f::enable(f::Alpha); 264 | assert_eq!(true, f::is_enabled(f::Alpha)); 265 | assert_eq!(false, f::is_enabled(f::Beta)); 266 | 267 | // Enable again 268 | f::enable(f::Alpha); 269 | assert_eq!(true, f::is_enabled(f::Alpha)); 270 | assert_eq!(false, f::is_enabled(f::Beta)); 271 | 272 | f::enable(f::Beta); 273 | assert_eq!(true, f::is_enabled(f::Alpha)); 274 | assert_eq!(true, f::is_enabled(f::Beta)); 275 | } 276 | 277 | #[test] 278 | fn disabling() { 279 | features! { 280 | pub mod f { 281 | const Cool = 0b01000000, 282 | const Beans = 0b10000000 283 | } 284 | } 285 | 286 | f::enable(f::Cool); 287 | f::enable(f::Beans); 288 | assert_eq!(true, f::is_enabled(f::Cool)); 289 | assert_eq!(true, f::is_enabled(f::Beans)); 290 | 291 | f::disable(f::Cool); 292 | assert_eq!(false, f::is_enabled(f::Cool)); 293 | assert_eq!(true, f::is_enabled(f::Beans)); 294 | 295 | // Disable again 296 | f::disable(f::Cool); 297 | assert_eq!(false, f::is_enabled(f::Cool)); 298 | assert_eq!(true, f::is_enabled(f::Beans)); 299 | 300 | f::disable(f::Beans); 301 | assert_eq!(false, f::is_enabled(f::Cool)); 302 | assert_eq!(false, f::is_enabled(f::Beans)); 303 | } 304 | } 305 | --------------------------------------------------------------------------------