Rint (Ruby Interface)
Rint provides a way to implement behaviour defined by Interface files, warning when the desired behaviour is missing.
require 'interface' module Playable include Interface def initialize must_implement :play, play_quietly: 1 end end class Instrument implements Playable end Instrument.new # will throw: Interface::Error::NotImplementedError: Expected Instrument to implement play for interface Playable
As showed in the example above,
must_implement allows you enforce the implementation of the methods, specifying the arity. When not specified, only the method implementation will be checked.
There is also a CLI to generate the interfaces from the command line:
$ rint c Playable play play_quietly:1
will generate lib/playable.rb (namespaces are also supported).
Add it to your Gemfile:
$ bundle install
Duck typing can be evil if not used correctly. While Ruby applications can get a good level of confidence about issues arisen by duck typing, the fear of a method missing exception or constant changes to a class may lead the developer to use safety checks such as respond_to? or raise Errors when a method is missing.
This implementation of rint wraps what other static languages use and encapsulates the safety check in a common place, also making explicit the behaviour through the word "implements" and expecting the developer to guess the behaviour of a class without looking at docs or partially implemented code.
It also provides a centralised way to implement the interface pattern without having the code throwing an error in a hidden method.
The environment variable DISABLE_RUBY_INTERFACE can be set to 1 in order to globally disable the interfaces - no Error will get thrown. This might be particularly useful in production for performance reasons if we are confident enough through tests that the interfaces are all implemented.
Create your feature branch (git checkout -b my-new-feature)
Commit your changes (git commit -am 'Add some feature')
Push to the branch (git push origin my-new-feature)
Create new Pull Request
Free Software, Hell Yeah!
Copyright 2015 James Lopez https://github.com/bluegod/rint