How to use included method of ClassMethods Package

2module ActiveSupport3  # A typical module looks like this:4  #5  #   module M6  #     def self.included(base)7  #       base.extend ClassMethods8  #       base.class_eval do9  #         scope :disabled, -> { where(disabled: true) }10  #       end11  #     end12  #13  #     module ClassMethods14  #       ...15  #     end16  #   end17  #18  # By using <tt>ActiveSupport::Concern</tt> the above module could instead be19  # written as:20  #21  #   require "active_support/concern"22  #23  #   module M24  #     extend ActiveSupport::Concern25  #26  #     included do27  #       scope :disabled, -> { where(disabled: true) }28  #     end29  #30  #     class_methods do31  #       ...32  #     end33  #   end34  #35  # Moreover, it gracefully handles module dependencies. Given a +Foo+ module36  # and a +Bar+ module which depends on the former, we would typically write the37  # following:38  #39  #   module Foo40  #     def self.included(base)41  #       base.class_eval do42  #         def self.method_injected_by_foo43  #           ...44  #         end45  #       end46  #     end47  #   end48  #49  #   module Bar50  #     def self.included(base)51  #       base.method_injected_by_foo52  #     end53  #   end54  #55  #   class Host56  #     include Foo # We need to include this dependency for Bar57  #     include Bar # Bar is the module that Host really needs58  #   end59  #60  # But why should +Host+ care about +Bar+'s dependencies, namely +Foo+? We61  # could try to hide these from +Host+ directly including +Foo+ in +Bar+:62  #63  #   module Bar64  #     include Foo65  #     def self.included(base)66  #       base.method_injected_by_foo67  #     end68  #   end69  #70  #   class Host71  #     include Bar72  #   end73  #74  # Unfortunately this won't work, since when +Foo+ is included, its <tt>base</tt>75  # is the +Bar+ module, not the +Host+ class. With <tt>ActiveSupport::Concern</tt>,76  # module dependencies are properly resolved:77  #78  #   require "active_support/concern"79  #80  #   module Foo81  #     extend ActiveSupport::Concern82  #     included do83  #       def self.method_injected_by_foo84  #         ...85  #       end86  #     end87  #   end88  #89  #   module Bar90  #     extend ActiveSupport::Concern91  #     include Foo92  #93  #     included do94  #       self.method_injected_by_foo95  #     end96  #   end97  #98  #   class Host99  #     include Bar # It works, now Bar takes care of its dependencies100  #   end101  #102  # === Prepending concerns103  #104  # Just like <tt>include</tt>, concerns also support <tt>prepend</tt> with a corresponding105  # <tt>prepended do</tt> callback. <tt>module ClassMethods</tt> or <tt>class_methods do</tt> are106  # prepended as well.107  #108  # <tt>prepend</tt> is also used for any dependencies.109  module Concern110    class MultipleIncludedBlocks < StandardError #:nodoc:111      def initialize112        super "Cannot define multiple 'included' blocks for a Concern"113      end114    end115    class MultiplePrependBlocks < StandardError #:nodoc:116      def initialize117        super "Cannot define multiple 'prepended' blocks for a Concern"118      end119    end120    def self.extended(base) #:nodoc:121      base.instance_variable_set(:@_dependencies, [])122    end123    def append_features(base) #:nodoc:124      if base.instance_variable_defined?(:@_dependencies)125        base.instance_variable_get(:@_dependencies) << self126        false127      else128        return false if base < self129        @_dependencies.each { |dep| base.include(dep) }130        super131        base.extend const_get(:ClassMethods) if const_defined?(:ClassMethods)132        base.class_eval(&@_included_block) if instance_variable_defined?(:@_included_block)133      end134    end135    def prepend_features(base) #:nodoc:136      if base.instance_variable_defined?(:@_dependencies)137        base.instance_variable_get(:@_dependencies).unshift self138        false139      else140        return false if base < self141        @_dependencies.each { |dep| base.prepend(dep) }142        super143        base.singleton_class.prepend const_get(:ClassMethods) if const_defined?(:ClassMethods)144        base.class_eval(&@_prepended_block) if instance_variable_defined?(:@_prepended_block)145      end146    end147    # Evaluate given block in context of base class,148    # so that you can write class macros here.149    # When you define more than one +included+ block, it raises an exception.150    def included(base = nil, &block)151      if base.nil?152        if instance_variable_defined?(:@_included_block)153          if @_included_block.source_location != block.source_location154            raise MultipleIncludedBlocks155          end156        else157          @_included_block = block158        end159      else160        super161      end162    end163    # Evaluate given block in context of base class,164    # so that you can write class macros here.165    # When you define more than one +prepended+ block, it raises an exception.166    def prepended(base = nil, &block)167      if base.nil?168        if instance_variable_defined?(:@_prepended_block)169          if @_prepended_block.source_location != block.source_location170            raise MultiplePrependBlocks171          end...

1  def self.included(base)2    base.extend(ClassMethods)3Your name to display (optional):

1  def self.included(base)2    base.extend(ClassMethods)3  def self.included(base)4    base.extend(ClassMethods)5  def self.included(base)6    base.extend(ClassMethods)7  def self.included(base)8    base.extend(ClassMethods)9  def self.included(base)10    base.extend(ClassMethods)11  def self.included(base)12    base.extend(ClassMethods)13  def self.included(base)14    base.extend(ClassMethods)