module Sprout

  ##
  # This class was copied from Rails source code and enhances
  # Ruby's native mixin functionality for our Sprout::RubyFeature.
  # 
  # I'd like to work to get rid of this class, and the confusion
  # that it introduces.
  #
  module Concern

    ##
    # Callback handler when a class is extended. This
    # handler will set the @_dependencies array on the
    # concrete class that just extended a 
    # 'Concern'.
    #
    # This callback is often triggered with:
    #
    #   class Foo
    #     extend Concern
    #   end
    #
    def self.extended(base)
      base.instance_variable_set("@_dependencies", [])
    end

    ##
    # Apply both class and instance features found in the 
    # base class to the new subclass.
    def append_features(base)
      if base.instance_variable_defined?("@_dependencies")
        base.instance_variable_get("@_dependencies") << self
        return false
      else
        return false if base < self
        @_dependencies.each { |dep| base.send(:include, dep) }
        super
        base.extend const_get("ClassMethods") if const_defined?("ClassMethods")
        base.send :include, const_get("InstanceMethods") if const_defined?("InstanceMethods")
        base.class_eval(&@_included_block) if instance_variable_defined?("@_included_block")
      end
    end

    ##
    # Handle inclusion of this module.
    def included(base = nil, &block)
      if base.nil?
        @_included_block = block
      else
        super
      end
    end
  end
end

=begin
Copyright (c) 2004-2010 David Heinemeier Hansson

Permission is hereby granted, free of charge, to any person obtaining
a copy of this software and associated documentation files (the
"Software"), to deal in the Software without restriction, including
without limitation the rights to use, copy, modify, merge, publish,
distribute, sublicense, and/or sell copies of the Software, and to
permit persons to whom the Software is furnished to do so, subject to
the following conditions:

The above copyright notice and this permission notice shall be
included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
=end

