Code style linter for Crystal
(a single-celled animal that catches food and moves about by extending fingerlike projections of protoplasm)
## About Ameba is a tool for enforcing a consistent Crystal code style, for catching code smells and wrong code constructions. Ameba's [rules](src/ameba/rules/) traverse AST and report bad parts of your code. Is still under construction, compatibility may be broken :construction: ## Installation ### As a project dependency: Add this to your application's `shard.yml`: ```yaml development_dependencies: ameba: github: veelenga/ameba ``` Compile and install `ameba` binary onto your system while running `crystal deps`. ### OS X ``` $ brew tap veelenga/tap $ brew install ameba ``` ### From sources ``` $ git clone https://github.com/veelenga/ameba && cd ameba $ make install ``` Or just compile it from sources `make install`. ## Usage Run `ameba` binary within your project directory to catch code issues: ```sh $ ameba Inspecting 52 files. .........................F.......F........F......... src/ameba/ast/traverse.cr:27:5 PredicateName: Favour method name 'node?' over 'is_node?' src/ameba/rules/empty_expression.cr:42:7 LiteralInCondition: Literal value found in conditional src/ameba/rules/empty_expression.cr:30:7 UnlessElse: Favour if over unless with else Finished in 10.53 milliseconds 52 inspected, 3 failures. ``` ## Configuration It is possible to configure or even disable specific rules using YAML configuration file. By default Ameba is looking for `.ameba.yml` in a project root directory. Copy and adjust [existed example](config/ameba.yml). ## Write a new Rule Adding a new rule is as simple as inheriting from `Rule::Base` struct and implementing your logic to detect a problem: ```crystal struct DebuggerStatement < Rule::Base # This is a required method to be implemented by the rule. # Source will be passed here. If rule finds an issue in this source, # it reports an error: # # source.error rule, line_number, message # def test(source) # This line deletegates verification to a particular AST visitor. AST::Visitor.new self, source end # This method is called once the visitor finds a required node. def test(source, node : Crystal::Call) # It reports an error, if there is `debugger` method call # without arguments and a receiver. That's it, somebody forgot # to remove a debugger statement. return unless node.name == "debugger" && node.args.empty? && node.obj.nil? source.error self, node.location, "Possible forgotten debugger statement detected" end end ``` ## Contributors - [veelenga](https://github.com/veelenga) Vitalii Elenhaupt - creator, maintainer