├── .github ├── CODE_OF_CONDUCT.md ├── CONTRIBUTING.md ├── ISSUE_TEMPLATE.md ├── ISSUE_TEMPLATE │ ├── bug_report.md │ ├── feature_request.md │ └── question.md ├── PULL_REQUEST_TEMPLATE.md └── stale.yml ├── .gitignore ├── .travis.yml ├── Cargo.toml ├── LICENSE-APACHE ├── LICENSE-MIT ├── README.md ├── examples ├── read_string.rs └── square.rs ├── src └── lib.rs └── tests └── test.rs /.github/CODE_OF_CONDUCT.md: -------------------------------------------------------------------------------- 1 | # Contributor Covenant Code of Conduct 2 | 3 | ## Our Pledge 4 | 5 | In the interest of fostering an open and welcoming environment, we as 6 | contributors and maintainers pledge to making participation in our project and 7 | our community a harassment-free experience for everyone, regardless of age, body 8 | size, disability, ethnicity, gender identity and expression, level of 9 | experience, 10 | education, socio-economic status, nationality, personal appearance, race, 11 | religion, or sexual identity and orientation. 12 | 13 | ## Our Standards 14 | 15 | Examples of behavior that contributes to creating a positive environment 16 | include: 17 | 18 | - Using welcoming and inclusive language 19 | - Being respectful of differing viewpoints and experiences 20 | - Gracefully accepting constructive criticism 21 | - Focusing on what is best for the community 22 | - Showing empathy towards other community members 23 | 24 | Examples of unacceptable behavior by participants include: 25 | 26 | - The use of sexualized language or imagery and unwelcome sexual attention or 27 | advances 28 | - Trolling, insulting/derogatory comments, and personal or political attacks 29 | - Public or private harassment 30 | - Publishing others' private information, such as a physical or electronic 31 | address, without explicit permission 32 | - Other conduct which could reasonably be considered inappropriate in a 33 | professional setting 34 | 35 | 36 | ## Our Responsibilities 37 | 38 | Project maintainers are responsible for clarifying the standards of acceptable 39 | behavior and are expected to take appropriate and fair corrective action in 40 | response to any instances of unacceptable behavior. 41 | 42 | Project maintainers have the right and responsibility to remove, edit, or 43 | reject comments, commits, code, wiki edits, issues, and other contributions 44 | that are not aligned to this Code of Conduct, or to ban temporarily or 45 | permanently any contributor for other behaviors that they deem inappropriate, 46 | threatening, offensive, or harmful. 47 | 48 | ## Scope 49 | 50 | This Code of Conduct applies both within project spaces and in public spaces 51 | when an individual is representing the project or its community. Examples of 52 | representing a project or community include using an official project e-mail 53 | address, posting via an official social media account, or acting as an appointed 54 | representative at an online or offline event. Representation of a project may be 55 | further defined and clarified by project maintainers. 56 | 57 | ## Enforcement 58 | 59 | Instances of abusive, harassing, or otherwise unacceptable behavior may be 60 | reported by contacting the project team at yoshuawuyts@gmail.com, or through 61 | IRC. All complaints will be reviewed and investigated and will result in a 62 | response that is deemed necessary and appropriate to the circumstances. The 63 | project team is obligated to maintain confidentiality with regard to the 64 | reporter of an incident. 65 | Further details of specific enforcement policies may be posted separately. 66 | 67 | Project maintainers who do not follow or enforce the Code of Conduct in good 68 | faith may face temporary or permanent repercussions as determined by other 69 | members of the project's leadership. 70 | 71 | ## Attribution 72 | 73 | This Code of Conduct is adapted from the Contributor Covenant, version 1.4, 74 | available at 75 | https://www.contributor-covenant.org/version/1/4/code-of-conduct.html 76 | -------------------------------------------------------------------------------- /.github/CONTRIBUTING.md: -------------------------------------------------------------------------------- 1 | # Contributing 2 | Contributions include code, documentation, answering user questions, running the 3 | project's infrastructure, and advocating for all types of users. 4 | 5 | The project welcomes all contributions from anyone willing to work in good faith 6 | with other contributors and the community. No contribution is too small and all 7 | contributions are valued. 8 | 9 | This guide explains the process for contributing to the project's GitHub 10 | Repository. 11 | 12 | - [Code of Conduct](#code-of-conduct) 13 | - [Bad Actors](#bad-actors) 14 | 15 | ## Code of Conduct 16 | The project has a [Code of Conduct](./CODE_OF_CONDUCT.md) that *all* 17 | contributors are expected to follow. This code describes the *minimum* behavior 18 | expectations for all contributors. 19 | 20 | As a contributor, how you choose to act and interact towards your 21 | fellow contributors, as well as to the community, will reflect back not only 22 | on yourself but on the project as a whole. The Code of Conduct is designed and 23 | intended, above all else, to help establish a culture within the project that 24 | allows anyone and everyone who wants to contribute to feel safe doing so. 25 | 26 | Should any individual act in any way that is considered in violation of the 27 | [Code of Conduct](./CODE_OF_CONDUCT.md), corrective actions will be taken. It is 28 | possible, however, for any individual to *act* in such a manner that is not in 29 | violation of the strict letter of the Code of Conduct guidelines while still 30 | going completely against the spirit of what that Code is intended to accomplish. 31 | 32 | Open, diverse, and inclusive communities live and die on the basis of trust. 33 | Contributors can disagree with one another so long as they trust that those 34 | disagreements are in good faith and everyone is working towards a common 35 | goal. 36 | 37 | ## Bad Actors 38 | All contributors to tacitly agree to abide by both the letter and 39 | spirit of the [Code of Conduct](./CODE_OF_CONDUCT.md). Failure, or 40 | unwillingness, to do so will result in contributions being respectfully 41 | declined. 42 | 43 | A *bad actor* is someone who repeatedly violates the *spirit* of the Code of 44 | Conduct through consistent failure to self-regulate the way in which they 45 | interact with other contributors in the project. In doing so, bad actors 46 | alienate other contributors, discourage collaboration, and generally reflect 47 | poorly on the project as a whole. 48 | 49 | Being a bad actor may be intentional or unintentional. Typically, unintentional 50 | bad behavior can be easily corrected by being quick to apologize and correct 51 | course *even if you are not entirely convinced you need to*. Giving other 52 | contributors the benefit of the doubt and having a sincere willingness to admit 53 | that you *might* be wrong is critical for any successful open collaboration. 54 | 55 | Don't be a bad actor. 56 | -------------------------------------------------------------------------------- /.github/ISSUE_TEMPLATE.md: -------------------------------------------------------------------------------- 1 | ## Summary 2 | Explain what is going on. 3 | 4 | ## Your Environment 5 | | Software | Version(s) | 6 | | ---------------- | ---------- | 7 | | context-attribute | 8 | | Rustc | 9 | | Operating System | 10 | -------------------------------------------------------------------------------- /.github/ISSUE_TEMPLATE/bug_report.md: -------------------------------------------------------------------------------- 1 | --- 2 | name: Bug Report 3 | about: Did something not work as expected? 4 | --- 5 | 6 | # Bug Report 7 | ## Your Environment 8 | | Software | Version(s) | 9 | | ---------------- | ---------- | 10 | | context-attribute | 11 | | Rustc | 12 | | Operating System | 13 | 14 | ## Expected Behavior 15 | Tell us what should have happened. 16 | 17 | ## Current Behavior 18 | Tell us what happens instead of the expected behavior. If you are seeing an 19 | error, please include the full error message and stack trace. 20 | 21 | ## Code Sample 22 | Please provide a code repository, gist, code snippet or sample files to 23 | reproduce the issue. 24 | -------------------------------------------------------------------------------- /.github/ISSUE_TEMPLATE/feature_request.md: -------------------------------------------------------------------------------- 1 | --- 2 | name: Feature Request 3 | about: Want us to add something to context-attribute? 4 | --- 5 | 6 | # Feature Request 7 | ## Summary 8 | One paragraph explanation of the feature. 9 | 10 | ## Motivation 11 | Why are we doing this? What use cases does it support? What is the expected 12 | outcome? 13 | 14 | ## Guide-level explanation 15 | Explain the proposal as if it was already included in the project and you 16 | were teaching it to another programmer. That generally means: 17 | 18 | - Introducing new named concepts. 19 | - Explaining the feature largely in terms of examples. 20 | - If applicable, provide sample error messages, deprecation warnings, or 21 | migration guidance. 22 | 23 | ## Reference-level explanation 24 | This is the technical portion of the feature request. Explain the design in 25 | sufficient detail that: 26 | 27 | - Its interaction with other features is clear. 28 | - It is reasonably clear how the feature would be implemented. 29 | - Corner cases are dissected by example. 30 | 31 | ## Drawbacks 32 | Why should we _not_ do this? 33 | 34 | ## Rationale and alternatives 35 | - Why is this design the best in the space of possible designs? 36 | - What other designs have been considered and what is the rationale for not 37 | choosing them? 38 | - What is the impact of not doing this? 39 | 40 | ## Unresolved Questions 41 | What related issues do you consider out of scope for this feature that could be 42 | addressed in the future independently of the solution that comes out of this 43 | feature? 44 | -------------------------------------------------------------------------------- /.github/ISSUE_TEMPLATE/question.md: -------------------------------------------------------------------------------- 1 | --- 2 | name: Question 3 | about: Have any questions regarding how context-attribute works? 4 | --- 5 | 6 | # Question 7 | ## Your Environment 8 | | Software | Version(s) | 9 | | ---------------- | ---------- | 10 | | context-attribute | 11 | | Rustc | 12 | | Operating System | 13 | 14 | ## Question 15 | Provide your question here. 16 | 17 | ## Context 18 | How has this issue affected you? What are you trying to accomplish? 19 | -------------------------------------------------------------------------------- /.github/PULL_REQUEST_TEMPLATE.md: -------------------------------------------------------------------------------- 1 | 2 | 3 | ## Description 4 | 5 | 6 | ## Motivation and Context 7 | 8 | 9 | 10 | ## Types of changes 11 | 12 | - [ ] Bug fix (non-breaking change which fixes an issue) 13 | - [ ] New feature (non-breaking change which adds functionality) 14 | - [ ] Breaking change (fix or feature that would cause existing functionality to change) 15 | -------------------------------------------------------------------------------- /.github/stale.yml: -------------------------------------------------------------------------------- 1 | # Configuration for probot-stale - https://github.com/probot/stale 2 | 3 | daysUntilStale: 90 4 | daysUntilClose: 7 5 | exemptLabels: 6 | - pinned 7 | - security 8 | exemptProjects: false 9 | exemptMilestones: false 10 | staleLabel: wontfix 11 | markComment: > 12 | This issue has been automatically marked as stale because it has not had 13 | recent activity. It will be closed if no further activity occurs. Thank you 14 | for your contributions. 15 | unmarkComment: false 16 | closeComment: false 17 | limitPerRun: 30 18 | -------------------------------------------------------------------------------- /.gitignore: -------------------------------------------------------------------------------- 1 | coverage/ 2 | target/ 3 | tmp/ 4 | dist/ 5 | npm-debug.log* 6 | Cargo.lock 7 | .DS_Store 8 | -------------------------------------------------------------------------------- /.travis.yml: -------------------------------------------------------------------------------- 1 | language: rust 2 | rust: 3 | - stable 4 | 5 | before_script: | 6 | rustup component add rustfmt-preview && 7 | rustup component add clippy-preview 8 | script: | 9 | cargo fmt -- --check && 10 | cargo clippy -- -D clippy && 11 | cargo build --verbose && 12 | cargo test --verbose 13 | cache: cargo 14 | -------------------------------------------------------------------------------- /Cargo.toml: -------------------------------------------------------------------------------- 1 | [package] 2 | name = "context-attribute" 3 | version = "1.0.0" 4 | license = "MIT OR Apache-2.0" 5 | repository = "https://github.com/yoshuawuyts/context-attribute" 6 | documentation = "https://docs.rs/context-attribute" 7 | description = "Set the error context using doc comments." 8 | keywords = ["doc", "failure", "context", "error", "macro"] 9 | categories = ["development-tools"] 10 | authors = ["Yoshua Wuyts "] 11 | readme = "README.md" 12 | edition = "2018" 13 | 14 | [lib] 15 | proc-macro = true 16 | 17 | [dependencies] 18 | failure = "0.1.5" 19 | syn = { version = "0.15", features = ["full", "extra-traits"] } 20 | proc-macro2 = { version = "0.4.24", features = ["nightly"] } 21 | quote = "0.6" 22 | 23 | [dev-dependencies] 24 | -------------------------------------------------------------------------------- /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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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 | -------------------------------------------------------------------------------- /README.md: -------------------------------------------------------------------------------- 1 | # context-attribute 2 | [![crates.io version][1]][2] [![build status][3]][4] 3 | [![downloads][5]][6] [![docs.rs docs][7]][8] 4 | 5 | Set the error [`context`] using doc comments. 6 | 7 | This is useful because instead of writing manual error messages to provide context to an error, it 8 | automatically derives it from doc comments. This works especially well for async contexts, where 9 | stack traces may not be persisted past yield points and thread boundaries. But contexts do. 10 | 11 | [`context`]: https://docs.rs/failure/0.1.5/failure/trait.ResultExt.html#tymethod.context 12 | 13 | - [Documentation][8] 14 | - [Crates.io][2] 15 | - [Releases][releases] 16 | 17 | ## Examples 18 | ```rust 19 | use context_attribute::context; 20 | use failure::{ensure, ResultExt}; 21 | 22 | /// Square a number if it's less than 10. 23 | #[context] 24 | fn square(num: usize) -> Result { 25 | ensure!(num < 10, "Number was too large"); 26 | Ok(num * num) 27 | } 28 | 29 | fn main() -> Result<(), failure::Error> { 30 | let args = std::env::args(); 31 | ensure!(args.len() == 2, "usage: square "); 32 | let input = args.skip(1).next().unwrap().parse()?; 33 | 34 | println!("result is {}", square(input)?); 35 | 36 | Ok(()) 37 | } 38 | ``` 39 | 40 | ```txt 41 | $ cargo run --example square 12 42 | Error: ErrorMessage { msg: "Number was too large" } 43 | Square a number if it's less than 10. 44 | ``` 45 | 46 | ## Installation 47 | ```sh 48 | $ cargo add context-attribute 49 | ``` 50 | 51 | ## FAQ 52 | ### What does the code expand to? 53 | Take this piece of code: 54 | ```rust 55 | /// Read address.txt from disk 56 | #[context] 57 | pub fn read_file_2() -> Result { 58 | Ok(std::fs::read_to_string("address.txt")?.trim().to_string()) 59 | } 60 | ``` 61 | Any error that comes from it is tagged with the message `"Read address.txt from disk"`. To write it 62 | by hand we'd have to do: 63 | 64 | ```rust 65 | /// Read address.txt from disk 66 | pub fn read_file_1() -> Result { 67 | let res = std::fs::read_to_string("address.txt") 68 | .context("Read address.txt from disk")? 69 | .trim() 70 | .to_string(); 71 | Ok(res) 72 | } 73 | ``` 74 | 75 | ## Safety 76 | This crate uses ``#![deny(unsafe_code)]`` to ensure everything is implemented in 77 | 100% Safe Rust. 78 | 79 | ## Contributing 80 | Want to join us? Check out our ["Contributing" guide][contributing] and take a 81 | look at some of these issues: 82 | 83 | - [Issues labeled "good first issue"][good-first-issue] 84 | - [Issues labeled "help wanted"][help-wanted] 85 | 86 | ## License 87 | [MIT](./LICENSE-MIT) OR [Apache-2.0](./LICENSE-APACHE) 88 | 89 | [1]: https://img.shields.io/crates/v/context-attribute.svg?style=flat-square 90 | [2]: https://crates.io/crates/context-attribute 91 | [3]: https://img.shields.io/travis/yoshuawuyts/context-attribute/master.svg?style=flat-square 92 | [4]: https://travis-ci.org/yoshuawuyts/context-attribute 93 | [5]: https://img.shields.io/crates/d/context-attribute.svg?style=flat-square 94 | [6]: https://crates.io/crates/context-attribute 95 | [7]: https://img.shields.io/badge/docs-latest-blue.svg?style=flat-square 96 | [8]: https://docs.rs/context-attribute 97 | 98 | [releases]: https://github.com/yoshuawuyts/context-attribute/releases 99 | [contributing]: https://github.com/yoshuawuyts/context-attribute/blob/master.github/CONTRIBUTING.md 100 | [good-first-issue]: https://github.com/yoshuawuyts/context-attribute/labels/good%20first%20issue 101 | [help-wanted]: https://github.com/yoshuawuyts/context-attribute/labels/help%20wanted 102 | -------------------------------------------------------------------------------- /examples/read_string.rs: -------------------------------------------------------------------------------- 1 | use context_attribute::context; 2 | use failure::{Error, ResultExt}; 3 | 4 | use std::fs; 5 | use std::net::SocketAddr; 6 | 7 | /// Read address.txt from disk 8 | fn read_file_1() -> Result { 9 | let res = std::fs::read_to_string("address.txt") 10 | .context("error reading address.txt from disk")? 11 | .trim() 12 | .to_string(); 13 | Ok(res) 14 | } 15 | 16 | /// Read address.txt from disk 17 | #[context] 18 | fn read_file_2() -> Result { 19 | Ok(std::fs::read_to_string("address.txt")?.trim().to_string()) 20 | } 21 | 22 | fn main() -> Result<(), Error> { 23 | read_file_1()?; 24 | read_file_2()?; 25 | Ok(()) 26 | } 27 | -------------------------------------------------------------------------------- /examples/square.rs: -------------------------------------------------------------------------------- 1 | use context_attribute::context; 2 | use failure::{ensure, ResultExt}; 3 | 4 | /// Square a number if it's less than 10. 5 | #[context] 6 | fn square(num: usize) -> Result { 7 | ensure!(num < 10, "Number was too large"); 8 | Ok(num * num) 9 | } 10 | 11 | fn main() -> Result<(), failure::Error> { 12 | let args = std::env::args(); 13 | ensure!(args.len() == 2, "usage: square "); 14 | let input = args.skip(1).next().unwrap().parse()?; 15 | 16 | println!("result is {}", square(input)?); 17 | 18 | Ok(()) 19 | } 20 | -------------------------------------------------------------------------------- /src/lib.rs: -------------------------------------------------------------------------------- 1 | //! Set the error [`context`] using doc comments. 2 | //! 3 | //! This is useful because instead of writing manual error messages to provide context to an error, it 4 | //! automatically derives it from doc comments. This works especially well for async contexts, where 5 | //! stack traces may not be persisted past yield points and thread boundaries. But contexts do. 6 | //! 7 | //! [`context`]: https://docs.rs/failure/0.1.5/failure/trait.ResultExt.html#tymethod.context 8 | //! 9 | //! ## Examples 10 | //! 11 | //! ```rust 12 | //! use context_attribute::context; 13 | //! use failure::{ensure, ResultExt}; 14 | //! 15 | //! /// Square a number if it's less than 10. 16 | //! #[context] 17 | //! fn square(num: usize) -> Result { 18 | //! ensure!(num < 10, "Number was too large"); 19 | //! Ok(num * num) 20 | //! } 21 | //! 22 | //! fn main() -> Result<(), failure::Error> { 23 | //! let args = std::env::args(); 24 | //! ensure!(args.len() == 2, "usage: square "); 25 | //! let input = args.skip(1).next().unwrap().parse()?; 26 | //! 27 | //! println!("result is {}", square(input)?); 28 | //! 29 | //! Ok(()) 30 | //! } 31 | //! ``` 32 | //! 33 | //! ```sh 34 | //! $ cargo run --example square 12 35 | //! Error: ErrorMessage { msg: "Number was too large" } 36 | //! Square a number if it's less than 10. 37 | //! ``` 38 | 39 | #![forbid(unsafe_code, future_incompatible, rust_2018_idioms)] 40 | #![deny(missing_debug_implementations, nonstandard_style)] 41 | #![warn(missing_docs, missing_doc_code_examples)] 42 | #![cfg_attr(test, deny(warnings))] 43 | #![recursion_limit = "512"] 44 | 45 | extern crate proc_macro; 46 | 47 | use proc_macro::TokenStream; 48 | use quote::{quote, quote_spanned}; 49 | use syn::spanned::Spanned; 50 | 51 | /// Use a doc comment to annotate the failure context of a function or try 52 | /// block. 53 | /// 54 | /// # Examples 55 | /// 56 | /// ``` 57 | /// use context_attribute::context; 58 | /// use failure::{ensure, ResultExt}; 59 | /// 60 | /// fn main() -> Result<(), failure::Error> { 61 | /// let _ = square(2)?; 62 | /// let _ = square(5)?; 63 | /// let _ = square(11)?; 64 | /// } 65 | /// 66 | /// /// Square a number if it's less than 10. 67 | /// #[context] 68 | /// fn square(num: usize) -> Result{ 69 | /// ensure!(num < 10, "Number was larger than 10"); 70 | /// num * num 71 | /// } 72 | /// ``` 73 | #[proc_macro_attribute] 74 | pub fn context(_attr: TokenStream, item: TokenStream) -> TokenStream { 75 | let input = syn::parse_macro_input!(item as syn::ItemFn); 76 | 77 | let attrs = &input.attrs; 78 | let doc = attrs.iter().find(|attr| format!("{}", attr.path.segments.first().unwrap().value().ident) == "doc"); 79 | let doc = match doc { 80 | Some(doc) => { 81 | let mut iter = doc.clone().tts.into_iter().skip(1); 82 | iter.next().unwrap() 83 | }, 84 | None => return TokenStream::from(quote_spanned! { 85 | input.span() => compile_error!("no doc comment provided") 86 | }), 87 | }; 88 | 89 | let vis = &input.vis; 90 | let constness = &input.constness; 91 | let unsafety = &input.unsafety; 92 | let asyncness = &input.asyncness; 93 | let abi = &input.abi; 94 | 95 | let generics = &input.decl.generics; 96 | let name = &input.ident; 97 | let inputs = &input.decl.inputs; 98 | let output = &input.decl.output; 99 | let body = &input.block.stmts; 100 | 101 | let args: Vec = inputs.pairs().filter_map(|pair| { 102 | match pair.into_value() { 103 | syn::FnArg::Captured(arg) => Some(arg.pat.clone()), 104 | _ => return None, 105 | } 106 | }).collect(); 107 | 108 | let result = quote! { 109 | #(#attrs)* 110 | #vis #constness #unsafety #asyncness #abi fn #generics #name(#(#inputs)*) #output { 111 | #constness #unsafety #asyncness #abi fn #generics #name(#(#inputs)*) #output { 112 | #(#body)* 113 | } 114 | Ok(#name(#(#args)*).context(#doc.trim())?) 115 | } 116 | }; 117 | 118 | result.into() 119 | } 120 | -------------------------------------------------------------------------------- /tests/test.rs: -------------------------------------------------------------------------------- 1 | extern crate context_attribute; 2 | extern crate failure; 3 | 4 | use failure::Error; 5 | 6 | #[test] 7 | fn should_work() -> Result<(), Error> { 8 | Ok(()) 9 | } 10 | --------------------------------------------------------------------------------