RUBY

rails include module

module Features
  FEATURES = [Running, Walking]

  # include Features::Running
  FEATURES.each do |feature|
    include feature
  end

  module ClassMethods
    # include Features::Running::ClassMethods
    FEATURES.each do |feature|
      include feature::ClassMethods
    end
  end

  module InstanceMethods
    def method_missing(meth)
      # Catch feature checks that are not included in models to return false
      if meth[-1] == '?' && meth.to_s =~ /can_(w+)z?/
        false
      else
        # You *must* call super if you don't handle the method,
        # otherwise you'll mess up Ruby's method lookup
        super
      end
    end
  end

  def self.included(base)
    base.send :extend, ClassMethods
    base.send :include, InstanceMethods
  end
end

# lib/features/running.rb
module Features::Running
  module ClassMethods
    def can_run
      ...

      # Define a method to have model know a way they have that feature
      define_method(:can_run?) { true }
    end
  end
end

# lib/features/walking.rb
module Features::Walking
  module ClassMethods
    def can_walk
      ...

      # Define a method to have model know a way they have that feature
      define_method(:can_walk?) { true }
    end
  end
end