From: "David A. Black" <dblack@...>
Date: 2008-12-14T22:23:34+09:00
Subject: Re: singleton methods vs. meta instance methods

Hi --

On Sun, 14 Dec 2008, Brian Candler wrote:

> Robert Dober wrote:
>> But... alas
>> you say that a meta.instance_methods returns both instance methods in
>> the metaclass plus the instance methods
>> of the actual class. I agree, you have shown this, however, :new,
>> :allocate & :superclass are instance methods of the metaclass, not of
>> the actual class, or are they not?
>
> I believe that they are instance methods of the actual class "Class".
>
> irb(main):002:0> Class.instance_methods(false)
> => ["allocate", "superclass", "new"]

Here's a demo of the consistency from the Class case to the SomeClass
case. I'm still not convinced that it's the ideal behavior.

$ cat sing.rb
class Object
   def singleton_class; class << self; self; end; end
end

class A
   def x; end
end

an_a = A.new
def an_a.y; end

p A.instance_methods(false)
p an_a.singleton_class.instance_methods(false)

$ ruby sing.rb
["x"]
["y", "x"]

$ ruby -pe 'gsub(/A/,"Class")' sing.rb | ruby -
["allocate", "superclass", "new", "x"]
["y", "allocate", "superclass", "new", "x"]


David

-- 
Rails training from David A. Black and Ruby Power and Light:
INTRO TO RAILS (Jan 12-15), Fort Lauderdale, FL
See http://www.rubypal.com for details
Coming in 2009: The Well-Grounded Rubyist (http://manning.com/black2)