Parametric Mixin

Parametric Mixins provides parameters for mixin modules. Module parameters can be set at the time of inclusion or extension using Module#[] method, then parameters can be accessed via the mixin_parameters method.

  module MyMixin
    include Paramix

    def hello
      puts "Hello from #{mixin_parameters[MyMixin][:name]}!"
    end
  end

  class MyClass
    include Mixin[:name => 'Ruby']
  end

  m = MyClass.new
  m.hello -> 'Hello from Ruby!'

You can view the full set of parameters via the mixin_parameters class method, which returns a hash keyed on the included modules.

  MyClass.mixin_parameters         #=> {MyMixin=>{:name=>'Ruby'}}
  MyClass.mixin_parameters[MyMixin]  #=> {:name=>'ruby'}

The include Praamix is equivalent to:

  def [](parameters)
    Paramix.new(self, parameters)
  end

Paramix.new can also take a block that injects code into the class or module including the parametric mixin. This is useful as an alternative to using the included callback for creating dynamic mixins.. For example:

  def self.[](parameters)
    Paramix.new(self, parameters) do
      attr_accessor mixin_params[MyMixin][:name]
    end
  end

As opposed to:

  module Mixin
    def self.included(base)
      base.class_eval do
        attr_accessor mixin_params[MyMixin][:name]
      end
    end
  end