Ruby9 Class & Modules 进阶

摘要

当模块被include时会被执行，同事会传递当前作用于的self对象

Ruby的内部类结构

Array.class # => Class Class.class # => Class

superclass 查看父类

Array.superclass # =>Object Object.superclass # =>BasicObject BasicObject.superclass # => nil

ancestors 查看当前类的继承链

Array.ancestors # => [Array, Enumerable, Object, Kernel, BasicObject]

Method Finding 方法查找

# class structure, method finding  class User   def panels     @panels ||= ['Profile', 'Products']   end end  class Admin < User end   puts Admin.ancestors admin = Admin.new  p admin.panels   # 从下往上查找 在admin中查找 找不到往上找User 然后Object 然后Kernel 然后 BasicObject

Method Overwrite 方法覆盖

1. class和module可以重新打开
2. 方法可以重定义

# 重新打开class  class User   def panels     @panels ||= ['Profile', 'Products']   end end  class User   def panels     'overwrite'   end end   puts User.ancestors admin = User.new  p admin.panels   # 从下往上查找 在admin中查找 找不到往上找User 然后Object 然后Kernel 然后 BasicObject

# overwrite and re-open  class Array   def to_hello_word     "hello #{self.join(', ')}"   end end  a = %w[cat horse dog] puts a.to_hello_word

# overwrite and re-open  a = %w[cat horse dog] puts a.join(',')  class Array   def join     'hello'   end end  puts '-' * 30 puts a.join

Module

Array.ancestors # => [Array, Enumerable, Object, Kernel, BasicObject] Enumerable.class # => Module Module.class # => Class

# module acts linke a class   module Management   def company_notifies     'company_notifies from management'   end end   class User   include Management    def company_notifies     puts super     'company_notifies from user'   end end  p User.ancestors  puts '-' * 30 user = User.new puts user.company_notifies

# module included sequence  module Management   def company_notifies     'company_notifies from management'   end end   module Track   def company_notifies     'company_notifies from track'   end end  class User   include Management   include Track    def company_notifies     puts super     'company_notifies from user'   end end   p User.ancestors   puts '-' * 30 user = User.new puts user.company_notifies

# 1 module included in module # 2 module acts as class  module Management   def company_notifies     'company_notifies from management'   end end   module Track   include Management    def company_notifies     puts super     'company_notifies from track'   end end   p Track.ancestors   puts '-' * 30 include Track puts company_notifies

# module's class method  module Management    def self.progress     'progress'   end    # you need to include/extend/prepend to use this metod   def company_notifies     'company_notifies from management'   end end    puts Management.progress

include vs prepend

1. include 把模块注入当前类的继承链(祖先链) 后面
2. prepend 把模块注入当前累的继承链(祖先链) 前面

# module include # include  module Management   def company_notifies     'company_notifies from management'   end end   class User   prepend Management   # include Management   def company_notifies     'company_notifies from user'   end end  p User.ancestors  puts '-' * 30 user = User.new puts user.company_notifies

include和exten方法

当模块被include时会被执行，同事会传递当前作用于的self对象

# included method  module Management   def self.included base     puts "Management is being included into #{base}"      base.include InstanceMethods     base.extend ClasMethods          module InstalceMethods       def company_notifies         'company_notifies from management'       end     end      module Classethods       def progress         'progress'       end     end    end end   class User   include Management end  puts '-' * 30 user = User.new puts user.company_notifies  puts '-' * 30 puts User.progress