Ruby extend and include

from URL: http://www.rsa.idv.tw/?p=151

Ruby modules有兩種方式mixed into a class，讓class可以簡易新增行為

1. include

通常用來新增Instance of mehtod

 

 

module  CMath

  def add(n)

    self + n

  end

end

Fixnum.class_eval do

  include CMath

end

puts  3.add 10

2. extend

通常用來新增class method

 

 

module ExtendMe

  def v_object_id

    “my object id is #{self.object_id}”

  end

end

class Person

  extend ExtendMe

end

puts Person.v_object_id

3. extend through include pattern

提供統一介面處理

 

 

module ExtendThroughIncludePattern

  def self.included(klass)

    klass.extend ClassMethods

  end

  def instance_method

    “this is an instance of #{self.class}”

  end

  module  ClassMethods

    def class_method

      “this is a method of the #{self} class”

    end

  end

end

class Person

    include ExtendThroughIncludePattern

end

puts Person.new.instance_method

puts Person.class_method

self.included
Callback invoked whenever the receiver is included in another module or class. This should be used in preference to Module.append_features if your code wants to perform some action when a module is included in another.

今天真的很兴奋，经过这么长时间，终于把Rails程序中权限控制按照我自己的想法实现了。特此留个记号，明天将正式发布我的权限控制插件。欢迎大家交流！