在Ruby中列出attr_accessors的最快/一线方式？

Question

列出所有定义方法的最短,单行方式是attr_accessor什么？我想这样做,如果我有一个类MyBaseClass,任何扩展它的东西,我可以attr_accessor在子类中定义.像这样的东西:

class MyBaseClass < Hash
  def attributes
    # ??
  end
end

class SubClass < MyBaseClass
  attr_accessor :id, :title, :body
end

puts SubClass.new.attributes.inspect #=> [id, title, body]

如何显示attr_reader和attr_writer定义？

Answer 1

提取的属性在一个数组,将它们分配到一个恒定,那么图示它们到attr_accessor.

class SubClass < MyBaseClass
  ATTRS = [:id, :title, :body]
  attr_accessor(*ATTRS)
end

现在您可以通过常量访问它们:

puts SubClass.ATTRS #=> [:id, :title, :body]

Answer 2

没有办法(单行或其他)列出attr_accessor定义的所有方法,只列出attr_accessor定义的方法而不定义自己的attr_accessor.

这是一个覆盖MyBaseClass中的attr_accessor的解决方案,用于记住使用attr_accessor创建的方法:

class MyBaseClass
  def self.attr_accessor(*vars)
    @attributes ||= []
    @attributes.concat vars
    super(*vars)
  end

  def self.attributes
    @attributes
  end

  def attributes
    self.class.attributes
  end
end

class SubClass < MyBaseClass
  attr_accessor :id, :title, :body
end

SubClass.new.attributes.inspect #=> [:id, :title, :body]

Answer 3

继承人使用mixin而不是继承:

module TrackAttributes
  def attr_readers
    self.class.instance_variable_get('@attr_readers')
  end

  def attr_writers
    self.class.instance_variable_get('@attr_writers')
  end

  def attr_accessors
    self.class.instance_variable_get('@attr_accessors')
  end

  def self.included(klass)
    klass.send :define_singleton_method, :attr_reader, ->(*params) do
      @attr_readers ||= []
      @attr_readers.concat params
      super(*params)
    end

    klass.send :define_singleton_method, :attr_writer, ->(*params) do
      @attr_writers ||= []
      @attr_writers.concat params
      super(*params)
    end

    klass.send :define_singleton_method, :attr_accessor, ->(*params) do
      @attr_accessors ||= []
      @attr_accessors.concat params
      super(*params)
    end
  end
end

class MyClass
  include TrackAttributes

  attr_accessor :id, :title, :body
end

MyClass.new.attr_accessors #=> [:id, :title, :body]