将类方法委托给Ruby中的对象 [英] Delegating class methods to an object in ruby

问题描述

我试图将对单例的调用包装在一个类中（因为我不希望其余代码知道它们正在与单例进行对话），所以我查看了委托模块。

I am trying to wrap calls to a singleton in a class (because I do not want the rest of the code to know that they are talking to a singleton), and I looked at the delegate module.

在我的代码中，我有这样的东西：

In my code, I have something like this:

class HideSingleton
  @@obj = SingletonClass.instance # x is an instance of SingletonClass
  # I want to be able to say HideSingleton.blah,
  # where 'blah' is instance method of SingletonClass instance (i.e., 'x')
  SimpleDelegator.new @@obj.field
end

class SingletonClass < BaseClass
  attr_reader :field
  def initialize
    @field = SimpleDelegator.new super(BaseClass Constructor params)
  end
end

然后在irb中：

> require 'singleton_class'
> x = SingletonClass.new
> x.blah  # 'blah' is a method that is present in BaseClass instance
> require 'hide_singleton'
> y = HideSingleton

我该怎么做 y.blah ？

推荐答案

我认为您尝试执行的操作比较简单，但是可以完成隐藏的单例类委托一个单例类，您可以执行以下操作：

I think there is a simpler implementation of what you are trying to do, but to accomplish the hidden singleton class that delegates to a singleton class, you can do the following:

require 'delegate'
require 'forwardable'

class BaseClass
  def blah
    puts 'hi'
  end
end

class SingletonClass < BaseClass
  attr_reader :field
  def initialize
    @field = SimpleDelegator.new(BaseClass.new)
  end
end

class HideSingleton
  def self.obj
    @@obj ||= SingletonClass.new.field
  end

  def self.method_missing *args
    obj.send *args
  end
end

然后您可以拨打以下电话：

You can then make the following calls:

x = SingletonClass.new
x.blah
hi
=> nil
HideSingleton.blah
hi
=> nil

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