Ruby Module---modules, components

• The main purpose of module is to put different methods and constants into different namespaces.
• The module is named in the same initial capitalization as the class, with multiple words without underlining. such as: Circlearea
• Module syntax
  Module ModuleName
  ......
  End
• The module uses the scope resolution operator "::" to invoke methods and constants in the module. For example:math::P i, math is the module name.
• Ways to import Modules:
  1. Require ' module '-----import module.
  Such as: Require ' date ', importing the date module, but not require ' date '
  The module name and scope resolution operators are used when calling methods and constants in module, such as math::P I
  
  2. Include module names, such as include Math
  Calling methods and constants in a module does not require the Write module name and scope resolution operator to be called directly. such as: cos (), without the need to write Math::cos ()
• you can think of module as a class that cannot be instantiated, cannot be inherited, and can be emulated with classes to implement multiple inheritance
  
  

  Module Martialarts
  Def Swordsman
  Puts "I ' m a swordsman."
  End
  End

  Class Ninja
  　　Include Martialarts
  Def initialize (clan)
  @clan = Clan
  End
  End

  Class Samurai
  　　Include Martialarts
  Def initialize (shogun)
  @shogun = Shogun
  End
  End

• The Include keyword lets an instance use the methods and constants in the model, and the Extend keyword allows the class to use the methods and constants in the model itself
  
  

  Module Thepresent
  def now
  Puts "It ' s #{time.new.hour > 12? Time.new.hour-12:time.new.hour}:#{time.new.min} #{time.new.hour > 12? ' PM ': ' AM '} (GMT). "
  End
  End

  Class Thehereand
  　　Extend Thepresent
  End

  Thehereand.now

Ruby Module---modules, components