From: "David A. Black" <dblack@...>
Date: 2008-09-30T19:37:00+09:00
Subject: Re: extend keyword in class definition

Hi --

On Tue, 30 Sep 2008, Sebastian Hungerecker wrote:

> ruud grosmann wrote:
>> Isn't a singleton method a method that applies to the
>> singleton class of one object?
>
> It is a method that is defined on the singleton class of an object, yes.
> As a singleton class by definition only has one instance that means that a
> singleton method is a method that can be called on a single object and that
> object only.

Although:

   class C
   end
   class D < C
   end

   def C.x
   end

   D.x     # subclass can call superclass's singleton methods

Technically, it's also true that if you extend an object with a
module, you're not really writing singleton methods, since the methods
in the module are available to other objects that use the module. The
singleton_method_added callback won't get called, for example.


David

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