From: Gary Wright <gwtmp01@...>
Date: 2010-12-03T13:05:20+09:00
Subject: Re: Singleton class, metaclass, eigenclass: what do they mean?


On Dec 2, 2010, at 6:59 PM, Tony Arcieri wrote:

> On Thu, Dec 2, 2010 at 4:55 PM, Gary Wright <gwtmp01@mac.com> wrote:
> 
>> Because some classes have behavior that is unique to the class.
>> 
> 
> Earlier I asked how this was implemented... apparently "class objects" have
> instance-specific behavior in their "singleton class" which takes the form
> of "singleton methods"?

Yes, but this is not special behavior for class objects.

Per-object behavior in Ruby is implemented by adding methods to the singleton
class for the object.  It doesn't matter if the object is a string, an array,
or a class.  The per-object methods (i.e. singleton methods) are all implemented
in the same way, via instance methods of the singleton class for the object.

If the object happens to be a class object then those singleton methods are
commonly known as 'class methods' but that is just a naming convention.

Gary Wright