Question

我正在阅读“Well Ground Ground Rubyist”一书，我对方法查找路径有疑问：

module M
  def report
    puts "'report' method in module M"
  end
end

module N
  def report
    puts "'report' method in module N"
  end
end

class C
  include M
  include N
  def report
    puts "'report' method in class C"
    puts "About to call super..."
    super
    puts "Back from super..."
  end
end

obj = C.new
obj.report

根据我的理解，obj.report将输出：

'report' method in class C
About to call super...
'report' method in module N
Back from super...

然而，我很好奇是否可以通过绕过N的报告从C类中调用M的报告方法。我知道如果我在模块N中添加“超级”，它将调用N的报告，然后是M的报告在放入“从超级......回来”之前，有没有办法直接从C？

这样做

Answer 1

您可以使用祖先反射：

class C
  def report
    my_ancestors = self.class.ancestors
    puts "my ancestors are: #{my_ancestors}"
    method = my_ancestors[2].instance_method(:report)
    method.bind(self).call
  end
end

C.new.report
=> my ancestors are: [C, N, M, Object, PP::ObjectMixin, Kernel, BasicObject]
=> 'report' method in module M

Answer 2

这样可行，但我觉得必须有一个更好的方法来做到这一点而不将其改为自我：

module M
   def self.report
      puts "'report' method in module M"
   end
end

Class C
include M
include N
def report
   puts "'report' method in class C"
   puts "About to call M.report..."
   M.report
   puts "About to call super..."
   super
    puts "Back from super..."
 end
 end

这个的输出是：

'report' method in class C
About to call M.report...
'report' method in module M
About to call super...
'report' method in module N
Back from super...

Ruby的方法查找路径

2 个答案: