Interfaceable

Impose interfaces on classes and let this gem automatically check that the interface constraints are met.

Installation

Add this line to your application's Gemfile:

gem 'interfaceable'

And then execute:

$ bundle install

Usage

In this example:

module Carrier
  def call(number); end

  def text(number, text); end
end

class Giffgaff
  extend Interfaceable

  implements Carrier
end

An attempt to load this code will result in the following error:

Giffgaff must implement: (Interfaceable::Error)
  - Carrier#text
  - Carrier#call

It will keep failing until Giffgaff defines those methods.

Correctly! E.g.:

class Giffgaff
  def call(number); end

  def text(number, text = ''); end
end

Will fail because of method signature mismatch:

Giffgaff must implement correctly: (Interfaceable::Error)
  - Carrier#text:
    - expected arguments: (req, req)
    - actual arguments: (req, opt=)

Rails

Mix in Interfaceable before any of the application code is loaded. For example, in the initializer. For extra peace of mind, you can noop interface checking in production:

# config/initializers/interfaceable.rb
class Class
  if Rails.env.production?
    def implements(*args); end
  else
    include Interfaceable
  end
end