ruby-on-rails - Ruby:在运行时观察方法(重新)定义

Question

我正在寻找一种方法(库或元编程技巧)来 Hook 方法定义，以便我可以扩展某些类并捕获它们的方法(重新)定义“事件”。

Answer 1

有 method_added 回调(参见 http://www.ruby-doc.org/core/classes/Module.html#M001662 不幸的是，没有文档)。您可以按如下方式使用它:

class Foo

  # define the callback...      
  def self.method_added(method_name)
    puts "I now have a method called #{method_name}"
  end

  # the callback is called on normal method definitions
  def foo
    # "I now have a method called foo" will be printed
  end

  # the callback is called on method definitions using define_method
  define_method :bar do
    # "I now have a method called bar" will be printed
  end

  # the callback is called on method definitions using alias and the likes
  alias :baz :foo # "I now have a method called baz" will be printed
end