如何提升attr_accessor中的红宝石？

问题描述

我想实现一个（类）方法 attr_accessor_with_client_reset ，它做同样的事情为 attr_accessor中，但每一个作家它另外执行

I want to implement a (class) method attr_accessor_with_client_reset, which does the same thing as attr_accessor, but on every writer it additionally executes

@client = nil

因此​​，例如，

So, for example,

attr_accessor_with_client_reset :foo

应该产生相同的结果。

should produce the same result as

attr_reader :foo

def foo=(value)
  @foo = value
  @client = nil
end

我如何做到这一点？

How do I achieve this?

推荐答案

Sergio的解决方案是好的，但不必要的复杂性：没有必要重复 attr_reader 的行为，可以直接委托给它。而且也没有必要让所有这双模块包括钩两轮牛车。另外， attr_accessor中需要多个名字，所以 attr_accessor_with_client_reset 也应该这样。

Sergio's solution is good, but needlessly complex: there's no need to duplicate the behavior of attr_reader, you can just delegate to it. And there's no need for all this double module include hook hackery. Plus, attr_accessor takes multiple names, so attr_accessor_with_client_reset should, too.

module AttrAccessorWithClientReset
  def attr_accessor_with_client_reset(*names)
    attr_reader *names

    names.each do |name|
      define_method :"#{name}=" do |v|
        instance_variable_set(:"@#{name}", v)
        @client = nil
      end
    end
  end
end

class Foo
  extend AttrAccessorWithClientReset

  attr_reader :client
  def initialize
    @foo = 0
    @client = 'client'
  end

  attr_accessor_with_client_reset :foo
end

f = Foo.new
f.foo    # => 0
f.client # => "client"
f.foo = 1
f.foo    # => 1
f.client # => nil

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