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fxn committed Aug 14, 2010
1 parent 25145d6 commit d6fd0f7
Showing 1 changed file with 22 additions and 32 deletions.
54 changes: 22 additions & 32 deletions activesupport/lib/active_support/concern.rb
Expand Up @@ -3,56 +3,56 @@ module ActiveSupport
#
# module M
# def self.included(base)
# base.send(:extend, ClassMethods)
# base.extend, ClassMethods
# base.send(:include, InstanceMethods)
# scope :foo, :conditions => { :created_at => nil }
# scope :disabled, where(:disabled => true)
# end
#
# module ClassMethods
# def cm; puts 'I am a class method'; end
# ...
# end
#
# module InstanceMethods
# def im; puts 'I am an instance method'; end
# ...
# end
# end
#
# By using <tt>ActiveSupport::Concern</tt> the above module could instead be written as:
#
#
# require 'active_support/concern'
#
# module M
# extend ActiveSupport::Concern
#
# included do
# scope :foo, :conditions => { :created_at => nil }
# scope :disabled, where(:disabled => true)
# end
#
# module ClassMethods
# def cm; puts 'I am a class method'; end
# ...
# end
#
# module InstanceMethods
# def im; puts 'I am an instance method'; end
# ...
# end
# end
#
# Moreover, it gracefully handles module dependencies. Given a Foo module and a Bar module which depends on the former, we would typically write the following:
# Moreover, it gracefully handles module dependencies. Given a +Foo+ module and a +Bar+
# module which depends on the former, we would typically write the following:
#
# module Foo
# def self.included(base)
# # Define some :enhanced_method for Host class
# base.class_eval do
# def self.enhanced_method
# # Do enhanced stuff
# def self.method_injected_by_foo
# ...
# end
# end
# end
# end
#
# module Bar
# def self.included(base)
# base.send(:enhanced_method)
# base.method_injected_by_foo
# end
# end
#
Expand All @@ -61,41 +61,31 @@ module ActiveSupport
# include Bar # Bar is the module that Host really needs
# end
#
# But why should Host care about Bar's dependencies, namely Foo? We could try to hide these from Host directly including Foo in Bar:
#
# module Foo
# def self.included(base)
# # Define some :enhanced_method for Host class
# base.class_eval do
# def self.enhanced_method
# # Do enhanced stuff
# end
# end
# end
# end
# But why should +Host+ care about +Bar+'s dependencies, namely +Foo+? We could try to hide
# these from +Host+ directly including +Foo+ in +Bar+:
#
# module Bar
# include Foo
# def self.included(base)
# base.send(:enhanced_method)
# base.method_injected_by_foo
# end
# end
#
# class Host
# include Bar
# end
#
# Unfortunately this won't work, since when Foo is included, its <tt>base</tt> is Bar module, not Host class.
# With <tt>ActiveSupport::Concern</tt>, module dependencies are properly resolved:
# Unfortunately this won't work, since when +Foo+ is included, its <tt>base</tt> is the +Bar+ module,
# not the +Host+ class. With <tt>ActiveSupport::Concern</tt>, module dependencies are properly resolved:
#
# require 'active_support/concern'
#
# module Foo
# extend ActiveSupport::Concern
# included do
# class_eval do
# def self.enhanced_method
# # Do enhanced stuff
# def self.method_injected_by_foo
# ...
# end
# end
# end
Expand All @@ -106,12 +96,12 @@ module ActiveSupport
# include Foo
#
# included do
# self.send(:enhanced_method)
# self.method_injected_by_foo
# end
# end
#
# class Host
# include Bar # Host only needs to care about Bar without needing to know about its dependencies
# include Bar # works, Bar takes care now of its dependencies
# end
#
module Concern
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