Ruby9 Class & Modules 进阶

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