Question

我想将特定消息发送给超类（参见示例）。基于原型的继承非常简单（因为我可以将消息发送到我的原型），但我很难在Ruby中做到这一点。

以下是我想做的简化示例

class BaseService
  def say_hello
    puts "hello"
  end
end

class SpecificService < BaseService
  def say_hello
    puts "hey you!"
    super
  end

  def say_hello_and_goodbye
    # send superclass the :say_hello message
    #
    # Couldn't find any references to superclass in docs,
    # so I make one up to show what I'd like to do.
    #
    # super.say_hello doesn't work either because super
    # looks up the superclass method :say_hello_and_goodbye

    superclass.say_hello
    puts "goodbye"
  end
end

SpecificService.new.say_hello
=> "hey you!"
=> "hello"

SpecificService.new.say_hello_and_goodbye
=> undefined local variable or method `superclass'

# desired
=> "hello"
=> "goodbye"

这个例子是人为的，但它证明了我的问题。反正我是否可以直接将消息传递给基类ala原型继承？

Answer 1

如果SpecificService覆盖了要在父级上调用的方法，则需要保存原始（父级）方法的句柄。查看alias_method。

class SpecificService < BaseService
  alias_method :original_say_hello, :say_hello

  def say_hello
    puts "hey you!"
    super
  end

  def say_hello_and_goodbye
    original_say_hello
    puts "goodbye"
  end
end

Ruby - 直接向超类发送消息

1 个答案: