Class Module 进阶

18 Oct 2017

ruby

Ruby的内部类结构

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

superclass (父类)

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

ancestors 继承链

Array.ancestors # => [Array, Enumberable, Object, kernel]

ruby方法查找是自下而上的

# class structure, method finding

class User
  def name
    "name form User class"
  end
end

class Admin < USer
end

admin = Admin.new

p admin.name # => "name form User class"

puts Admin.ancestors => [Admin, User, ..., ...]

Method Overwrite

class User
  def name
    "name form User class"
  end
end

class User
  def name
    "Overwrite"
  end
end

user = User.new
puts user.name

Module本质上也是class(不能实例化的class)

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

module Management
  def company_notifies
    "company_notifies from Management"
  end
end

class User
  include Management #可被当做User的父类

  def company_notifies
    puts super #调用父类同名方法
    "company_notifies from User"
  end

end

p User.ancestors # => [User, Management, Object ...]

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 #可被当做User的父类
  include Track

  def company_notifies
    puts super #调用Track
    "company_notifies from User"
  end

end

p User.ancestors # => [User, Track, Management, Object ...]

module Management
  def company_notifies
    "company_notifies from Management"
  end
end

module Track
  include Management
  def company_notifies
    puts super #可以调用到Management
    "company_notifies from Track"
  end
end

p Track.ancestors # => [Track, Management]

include Track #模块内部的实例方法是不被直接在外部空间调用的，必须先include到当前的命名空间。

module Management
  def self.progress
    "progress"
  end

  #you need to include prepend extend
  def company_notifies
    "company_notifies from Management"
  end
end

puts Management.progress

include vs prepend

include 把模块注入当前类的继承链后面
prepend 把模块注入当前类的继承链前面
extend 注入为类方法

module Management
  def company_notifies
    "company_notifies from Management"
  end
end

class User
  include Management
  #prepend Management

  def company_notifies
    "company_notifies from user"
  end
end

puts User.ancestors

included 方法

当模块被include时会被执行，同时会传递当前作用域的self对象

module Management
  def self.included base
    puts "Management is being included into #{base}"

    base.include InstanceMethods
    base.extend ClassMethods
  end

  module InstanceMethods
    def company_notifies
      "company_notifies frome Management"
    end
  end

  module ClassMethods
    def progress
      "progress"
    end
  end

end

class User
  include Management
end

user = User.new
puts User.progress
puts user.company_notifies