From: Adam Salter <adam.q.salter@...>
Date: 2007-12-13T14:00:10+09:00
Subject: Re: Inheritance and meta-classes

Any suggestions?
(or has the subject been done to death...)

I still don't get how you can query and see where in the chain a  
method got added to an object...

I've now found that you can do:
obj.class.ancestors # => Array

But that still doesn't include metaclasses...

How does Ruby know??

On 13/12/2007, at 10:15 AM, Adam Salter wrote:

> Hi all,
>
> OK. I'm trying to work out where a method is defined in Rails.
> It's in a test, and the specific function that's being called is  
> 'post', but my question is not a Rails question, it's Ruby.
>
> How do I find where a function is defined in the inheritance tree?
> Because of metaclass inheritance being cyclical I don't know where  
> to stop looking.
>
> I made the following as a test but I still can't find the function  
> being called so I'm guessing I'm missing some of the inheritance  
> tree...
>
> module Debugs
>  def find_respond_to_in_class_heirarchy(obj, method)
>    if obj.respond_to?(:superclass)
>      arr = find_respond_to_in_class_heirarchy(obj.superclass, method)
>      arr.unshift([obj.class.respond_to?(method),  
> obj.metaclass.respond_to?(method), obj.superclass.respond_to? 
> (method)])
>    elsif obj.nil?
>      arr = [[nil.class.respond_to?(method), nil.metaclass.respond_to? 
> (method), NoMethodError]]
>    else
>      arr = find_respond_to_in_class_heirarchy(obj.class, method)
>      arr.unshift([obj.class.respond_to?(method),  
> obj.metaclass.respond_to?(method), NoMethodError])
>    end
>    arr
>  end
> end
>
> class Object
>  include Debugs
>  def metaclass
>    class << self
>      self
>    end
>  end
> end
>
> Wow this whole metaclass, class, object, module relationship is  
> pretty mindbending...
>
> Cheers,
> -Adam
>