### Ameba

Code style linter for Crystal

(a single-celled animal that catches food and moves about by extending fingerlike projections of protoplasm)

- [About](#about) - [Usage](#usage) - [Watch a tutorial](#watch-a-tutorial) - [Autocorrection](#autocorrection) - [Explain issues](#explain-issues) - [Run in parallel](#run-in-parallel) - [Installation](#installation) - [As a project dependency:](#as-a-project-dependency) - [OS X](#os-x) - [Docker](#docker) - [From sources](#from-sources) - [Configuration](#configuration) - [Sources](#sources) - [Rules](#rules) - [Inline disabling](#inline-disabling) - [Editors \& integrations](#editors--integrations) - [Credits \& inspirations](#credits--inspirations) - [Contributors](#contributors) ## About Ameba is a static code analysis tool for the Crystal language. It enforces a consistent [Crystal code style](https://crystal-lang.org/reference/conventions/coding_style.html), also catches code smells and wrong code constructions. See also [Roadmap](https://github.com/crystal-ameba/ameba/wiki). ## Usage Run `ameba` binary within your project directory to catch code issues: ```sh $ ameba Inspecting 107 files ...............F.....................FF.................................................................... src/ameba/formatter/flycheck_formatter.cr:6:37 [W] Lint/UnusedArgument: Unused argument `location`. If it's necessary, use `_` as an argument name to indicate that it won't be used. > source.issues.each do |issue, location| ^ src/ameba/formatter/base_formatter.cr:16:14 [W] Lint/UselessAssign: Useless assignment to variable `s` > return s += issues.size ^ src/ameba/formatter/base_formatter.cr:16:7 [Correctable] [C] Style/RedundantReturn: Redundant `return` detected > return s += issues.size ^---------------------^ Finished in 389.45 milliseconds 107 inspected, 3 failures ``` ### Watch a tutorial [🎬 Watch the LuckyCast showing how to use Ameba](https://luckycasts.com/videos/ameba) ### Autocorrection Rules that are marked as `[Correctable]` in the output can be automatically corrected using `--fix` flag: ```sh $ ameba --fix ``` ### Explain issues Ameba allows you to dig deeper into an issue, by showing you details about the issue and the reasoning by it being reported. To be convenient, you can just copy-paste the `PATH:line:column` string from the report and paste behind the `ameba` command to check it out. ```sh $ ameba crystal/command/format.cr:26:83 # show explanation for the issue $ ameba --explain crystal/command/format.cr:26:83 # same thing ``` ### Run in parallel Some quick benchmark results measured while running Ameba on Crystal repo: ```sh $ CRYSTAL_WORKERS=1 ameba #=> 29.11 seconds $ CRYSTAL_WORKERS=2 ameba #=> 19.49 seconds $ CRYSTAL_WORKERS=4 ameba #=> 13.48 seconds $ CRYSTAL_WORKERS=8 ameba #=> 10.14 seconds ``` ## Installation ### As a project dependency: Add this to your application's `shard.yml`: ```yaml development_dependencies: ameba: github: crystal-ameba/ameba version: ~> 1.4.0 ``` Build `bin/ameba` binary within your project directory while running `shards install`. ### OS X ```sh $ brew tap crystal-ameba/ameba $ brew install ameba ``` ### Docker Build the image: ```sh $ docker build -t ghcr.io/crystal-ameba/ameba . ``` To use the resulting image on a local source folder, mount the current (or target) directory into `/src`: ```sh $ docker run -v $(pwd):/src ghcr.io/crystal-ameba/ameba ``` Also available on GitHub: https://github.com/crystal-ameba/ameba/pkgs/container/ameba ### From sources ```sh $ git clone https://github.com/crystal-ameba/ameba && cd ameba $ make install ``` ## Configuration Default configuration file is `.ameba.yml`. It allows to configure rule properties, disable specific rules and exclude sources from the rules. Generate new file by running `ameba --gen-config`. ### Sources **List of sources to run Ameba on can be configured globally via:** - `Globs` section - an array of wildcards (or paths) to include to the inspection. Defaults to `%w(**/*.cr !lib)`, meaning it includes all project files with `*.cr` extension except those which exist in `lib` folder. - `Excluded` section - an array of wildcards (or paths) to exclude from the source list defined by `Globs`. Defaults to an empty array. In this example we define default globs and exclude `src/compiler` folder: ``` yaml Globs: - "**/*.cr" - "!lib" Excluded: - src/compiler ``` **Specific sources can be excluded at rule level**: ``` yaml Style/RedundantBegin: Excluded: - src/server/processor.cr - src/server/api.cr ``` ### Rules One or more rules, or a one or more group of rules can be included or excluded via command line arguments: ```sh $ ameba --only Lint/Syntax # runs only Lint/Syntax rule $ ameba --only Style,Lint # runs only rules from Style and Lint groups $ ameba --except Lint/Syntax # runs all rules except Lint/Syntax $ ameba --except Style,Lint # runs all rules except rules in Style and Lint groups ``` Or through the configuration file: ``` yaml Style/RedundantBegin: Enabled: false ``` ### Inline disabling One or more rules or one or more group of rules can be disabled using inline directives: ```crystal # ameba:disable Style/LargeNumbers time = Time.epoch(1483859302) time = Time.epoch(1483859302) # ameba:disable Style/LargeNumbers, Lint/UselessAssign time = Time.epoch(1483859302) # ameba:disable Style, Lint ``` ## Editors & integrations - Vim: [vim-crystal](https://github.com/rhysd/vim-crystal), [Ale](https://github.com/w0rp/ale) - Emacs: [ameba.el](https://github.com/crystal-ameba/ameba.el) - Sublime Text: [Sublime Linter Ameba](https://github.com/epergo/SublimeLinter-contrib-ameba) - VSCode: [vscode-crystal-ameba](https://github.com/crystal-ameba/vscode-crystal-ameba) - Codacy: [codacy-ameba](https://github.com/codacy/codacy-ameba) - GitHub Actions: [github-action](https://github.com/crystal-ameba/github-action) ## Credits & inspirations - [Crystal Language](https://crystal-lang.org) - [Rubocop](https://rubocop.readthedocs.io/en/latest/) - [Credo](http://credo-ci.org/) - [Dogma](https://github.com/lpil/dogma) ## Contributors - [veelenga](https://github.com/veelenga) Vitalii Elenhaupt - creator, maintainer - [Sija](https://github.com/Sija) Sijawusz Pur Rahnama - maintainer