Ruby: Catching All Methods Sent to an Object

Question

I'm making a weird class where I want to catch every method sent to an object of the class. I can achieve most of what I want with method_missing e.g.

class MyClass
    def method_missing m, *args
        # do stuff
    end
end

The problem then is all of the instance methods that MyClass inherits from Object. I could go through each method one-by-one and redefine them, but I was hoping for a more flexible approach. All of the metaprogramming methods I've tried have complained with a NameError when I try to touch those instance methods.

Answer 1

As noted in the comments and the answer from @DanCheail, if you're using ruby 1.9+ you should use a BasicObject rather than undefining methods of Object. At the time of this posting usage of 1.8.x was still quite prevalent, even though 1.9 had been released for some time.

---

Rather than attempting to "redefine" anything, you could wrap your object in a blanked (for the most part) proxy object, something like:

class MyProxy
  instance_methods.each do |meth|
    # skipping undef of methods that "may cause serious problems"
    undef_method(meth) if meth !~ /^(__|object_id)/
  end

  def initialize(object)
    @object = object
  end     

  def method_missing(*args)
    # do stuff
    p args
    # ...
    @object.send(*args)
  end
end

MyProxy.new(MyClass.new).whatever

Answer 2

If you're using Ruby 1.9, you can have your class inherit from BasicObject to get a clean slate to work from:

http://ruby-doc.org/core-1.9/classes/BasicObject.html

Answer 3

If you're using Ruby 1.8 you can consider using the blankslate gem.