Extends the given modules to the classes that subsequently include the invoking module or one of its submodules.

Calling SomeMixin.class_extend(SomeClassMethods) would be equivalent to:

  module SomeMixin
    class_mixin do
      include SomeClassMethods
    end
  end

Works like class_extend except that the given modules are instead extended to the invoking module and the modules that subsequently include it rather than their including classes.

Returns the invoking modules‘s class_mixin module object. When a block is passed, it is evaluated in the context of the class_mixin module.

Given the module M, M‘s class_mixin module is included by the class_mixin module of any module that includes M and is extended to any class that includes M.

  module Active
    class_mixin do
      def active?; true; end
    end
  end

  module Hyper
    include Active
    class_mixin do
      def hyper?; true; end
    end
  end

  class HyperClass
    include Hyper
  end

  HyperClass.active? -> true
  HyperClass.hyper?  -> true

Works the same as class_mixin except that the invoking module‘s module_mixin is instead extended to the invoking module itself rather than its including classes.

  module Active
    module_mixin do
      def active_mixin?; true; end
    end
  end

  module Hyper
    include Active
  end

  class ActiveClass
    include Active
  end

  Active.active_mixin?                    -> true
  Hyper.active_mixin?                     -> true
  ActiveClass.respond_to?(:active_mixin?) -> false