优化是否仅适用于实例方法？

Question

我正在尝试理解Ruby的改进功能,我遇到了一个我不理解的场景.

以此示例代码为例:

class Traveller
  def what_are_you
    puts "I'm a Backpacker"
  end

  def self.preferred_accommodation
    puts "Hostels"
  end
end


module Refinements
  module Money
    def what_are_you
      puts "I'm a cashed-up hedonist!"
    end

    module ClassMethods
      def preferred_accommodation
        puts "Expensive Hotels"
      end
    end

    def self.included(base)
      base.extend ClassMethods
    end
  end

  refine Traveller do
    include Money
  end
end

现在,当我在REPL中执行此操作时:

Traveller.new.what_are_you         # => I'm a Backpacker
Traveller.preferred_accommodation  # => Hostels

using Refinements

Traveller.new.what_are_you         # => I'm a cashed-up hedonist!
Traveller.preferred_accommodation  # => Hostels (???)

为什么#what_are_you精致,但.preferred_accommodation不是？

Answer 1

正如@MasashiMiyazaki解释的那样,你必须改进两个类:Traveller和Traveller单身类.这实际上允许您简化代码:

module Money
  refine Traveller do
    def what_are_you
      puts "I'm a cashed-up hedonist!"
    end
  end

  refine Traveller.singleton_class do
    def preferred_accommodation
      puts "Expensive Hotels"
    end
  end
end

Traveller.new.what_are_you         #=> I'm a Backpacker
Traveller.preferred_accommodation  #=> Hostels

using Money
Traveller.new.what_are_you         #=> I'm a cashed-up hedonist!
Traveller.preferred_accommodation  #=> Expensive Hotels

此外,通过将上述三个语句放在一个模块中,这两个方法的精炼版本仅限于该模块:

module M
  using Money
  Traveller.new.what_are_you         #=> I'm a cashed-up hedonist!
  Traveller.preferred_accommodation  #=> Expensive Hotels
end

Traveller.new.what_are_you           #=> I'm a Backpacker
Traveller.preferred_accommodation    #=> Hostels

Answer 2

您需要使用singleton_class范围调用优化Traveler来覆盖类方法.通过将以下代码添加到您的优化模块而不是self.included,您可以获得预期的结果.

module Refinements
  refine Traveller.singleton_class do
    include Money::ClassMethods
  end
end

本文(http://timelessrepo.com/refinements-in-ruby)将帮助您更多地了解优化.