From: "David A. Black" Date: 2005-12-07T00:11:15+09:00 Subject: Re: Subclassing Class. Hi -- On Tue, 6 Dec 2005, Martin DeMello wrote: > John Carter 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. A lot of the usage I've seen is from newcomers who see the term used by non-newcomers and have no reason (because the situation is not explained to them) to believe that it's anything but the standard, official term. > 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". That may be due to restraint on the part of people who prefer other terms than "eigenclass" but don't think there should be a "vote"-by-pre-emptive-usage contest in this area. I suppose I could start telling people that there's a thing called the "own class" in Ruby (a term I've suggested) but I've chosen not to. David __ David A. Black dblack@wobblini.net "Ruby for Rails", forthcoming from Manning Publications, April 2006!