20分鐘ruby

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ref:https://www.ruby-lang.org/en/documentation/quickstart/

#!/usr/bin/env rubyclass MegaGreeter  attr_accessor :names  # Create the object  def initialize(names = "World")    @names = names  end  # Say hi to everybody  def say_hi    if @names.nil?      puts "..."    elsif @names.respond_to?("each")      # @names is a list of some kind, iterate!      @names.each do |name|        puts "Hello #{name}!"      end    else      puts "Hello #{@names}!"    end  end  # Say bye to everybody  def say_bye    if @names.nil?      puts "..."    elsif @names.respond_to?("join")      # Join the list elements with commas      puts "Goodbye #{@names.join(", ")}.  Come back soon!"    else      puts "Goodbye #{@names}.  Come back soon!"    end  endendif __FILE__ == $0  mg = MegaGreeter.new  mg.say_hi  mg.say_bye  # Change name to be "Zeke"  mg.names = "Zeke"  mg.say_hi  mg.say_bye  # Change the name to an array of names  mg.names = ["Albert", "Brenda", "Charles",              "Dave", "Engelbert"]  mg.say_hi  mg.say_bye  # Change to nil  mg.names = nil  mg.say_hi  mg.say_byeend

 1. attr_accseeor  :name

  使 MegaGreeter.instance_methods false 的傳回值(Array)多了  :id :id= 兩項

      mg.respond_to? :id   或  mg.respond_to?("id")    

      mg.respond_to? :id=  或 mg.respond_to?("id=")    為true

2. 使用對象的屬性而非對象的類型決定執行方式

    @names.respond_to?

3.   __FILE__==$0

  

   

20分鐘ruby