From: Martin DeMello <martindemello@...>
Date: 2005-12-06T23:42:34+09:00
Subject: Re: Subclassing Class.

John Carter <john.carter@tait.co.nz> wrote:
> Hmm. It's perfectly standard mathematical terminology for an operator A, 
> if you can find a limited subset of items e_i such that A operating on 
> item e_i results in the same item e_i (upto a scalar factor), then 
> the e_i are called an eigenstate of the operator A and the scalar factor 
> is the eigenvalue.
> 
> This usage of the term "eigen" is far far wider than ruby and far far 
> older.
> 
> If this usage maps in some fairly clear manner onto singleton classes then 
> clearly the term singleton class should be dropped in favour of 
> eigenclass.
> 
> The question then is "Is there an operation which leaves the singleton 
> classes, and only the singleton classes, unaltered (except perhaps in some 
> trivial fashion)?"

The mathematical usage draws on the German word for "own", as does
"eigenclass". It's a lot less ambiguous a term than "singleton class",
and the fact that it's a pleasing and apt term is indicated by the
number of rubyists who implicitly vote by using it. I don't think any
other term has caught on as well since people started expressing
dissatisfaction with the ambiguous nature of "singleton class" and
"metaclass".

martin