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### 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) * [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) * [Explain issues](#explain-issues) * [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.....................F.................................................................... src/ameba/formatter/flycheck_formatter.cr:4:33 [W] Lint/UnusedArgument: Unused argument `location` > source.issues.each do |e, location| ^ src/ameba/formatter/base_formatter.cr:12:7 [W] Lint/UselessAssign: Useless assignment to variable `s` > return s += issues.size ^ Finished in 542.64 milliseconds 129 inspected, 2 failures ``` ### Watch a tutorial [🎬 Watch the LuckyCast showing how to use Ameba](https://luckycasts.com/videos/ameba) ### Run in parallel Starting from 0.31.0 Crystal [supports parallelism](https://crystal-lang.org/2019/09/06/parallelism-in-crystal.html). It allows to run linting in parallel too. In order to take advantage of this feature you need to build ameba with preview_mt support: ```sh $ crystal build src/cli.cr -Dpreview_mt -o bin/ameba $ make install ``` 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: ~> 1.0.0 ``` Build `bin/ameba` binary within your project directory while running `shards install`. You may also want to use it on [Travis](travis-ci.org): ```yaml # .travis.yml language: crystal install: - shards install script: - crystal spec - crystal bin/ameba.cr ``` Using this config Ameba will inspect files just after the specs run. Travis will also fail the build if some problems detected. ### OS X ```sh $ brew tap veelenga/tap $ brew install ameba ``` ### Docker Build the image: ```sh $ docker build -t 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 crystal-ameba/ameba ``` Also available on DockerHub: https://hub.docker.com/r/veelenga/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 ``` ### 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 ``` ### 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