From: Dominik Bathon <dbatml@...>
Date: 2005-12-23T13:00:27+09:00
Subject: Re: How do you know what class defines method foo()?

On Fri, 23 Dec 2005 00:12:51 +0100, Logan Capaldo <logancapaldo@gmail.com>  
wrote:

> Array.method_defined?(:partition)
> #=> true
>
> Enumerable.method_defined?(:partition)
> #=> true
>
> Same for instance_methods.include?.
> If we loop forward through ancestors, we get Array as the answer. If we  
> loop backwards we get Enumerable. The problem is, looping backwards will  
> get us the wrong answer if Array overrides partition. I can't think of a  
> good why to do this unless there is a Class#overrides? method. (e.g.  
> Array.overrides?(:partition) #=> false ).

I just played a bit around and found Method#inspect:

>> a = []
=> []
>> a.method(:partition)
=> #<Method: Array(Enumerable)#partition>
>> a.method(:first)
=> #<Method: Array#first>
>> a.method(:send)
=> #<Method: Array(Kernel)#send>
>> class Array; def send *a; super end end
=> nil
>> a.method(:send)
=> #<Method: Array#send>

So, if just want to know it for one case, use irb and look at  
Method#inspect.

To write a method that returns the class/module that defines a method one  
might parse the output of Method#inspect, but I think that is not very  
nice.

There doesn't seem to be a direct way to get the class/module in Ruby.


Dominik