如何在Rails 3.1中复制class_inheritable_accessor的行为？

Question

从Rails 3.1开始,class_inheritable_accessor产生弃用警告,告诉我改为使用class_attribute.但是class_attribute我将以一种重要的方式表现出不同的表现.

典型的用法class_inheritable_attribute是演示者类,如下所示:

module Presenter
  class Base
    class_inheritable_accessor :presented
    self.presented = {}

    def self.presents(*types)
      types_and_classes = types.extract_options!
      types.each {|t| types_and_classes[t] = t.to_s.tableize.classify.constantize }
      attr_accessor *types_and_classes.keys
      types_and_classes.keys.each do |t|
        presented[t] = types_and_classes[t]
      end
    end
  end
end

class PresenterTest < Presenter::Base
  presents :user, :person
end

Presenter::Base.presented => {}
PresenterTest.presented => {:user => User, :person => Person}

但使用class_attribute子类会污染他们的父母:

Presenter::Base => {:user => User, :person => Person}

这根本不是理想的行为.是否有其他类型的访问器行为正确,或者我是否需要完全切换到另一种模式？我应该如何复制相同的行为class_inheritable_accessor？

Answer 1

class_attribute如果按预期使用,则不会污染其父母.确保您没有就地更改可变项目.

types_and_classes.keys.each do |t|
  self.presented = presented.merge({t => types_and_classes[t]})
end