From: Greg Weeks <gregweeks@...>
Date: 2007-11-11T18:00:48+09:00
Subject: Re: bug in nested defs (?)

Ryan Davis wrote:
> On Nov 10, 2007, at 23:40 , Greg Weeks wrote:
> 
>>  not a class, then the method is a singleton method of the context
>>  object.
> 
> not quite. see "Defining a Method" of the pickaxe ed 2 on page 330.

I now see that you're right.   The Pick-axe book explains everything:

    "A method definition using an unadorned method name within a class
    or module definition creates an instance method".

Here, "within" means lexically within, not dynamically within.  This
explains my problem case:

  module Definer
    def def_foo
      def foo ; "foo" ; end # class method of User !
    end
  end
  class User
    extend Definer
    def_foo
  end
  User.foo    # works!
  User.new.foo    # error!

The def of foo is dynamically within User, but it is lexically within
Definer.  (The fact that it is nested doesn't matter.)  Consequently,
foo becomes an instance method of Definer.

This also implies (correctly) that the foo method of y is a common
method, not a singleton method.  So I was wrong about that too.  But I
think I've got it now.  Yippee!

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