From: "Jörg W Mittag" <JoergWMittag+Usenet@...>
Date: 2009-05-16T07:00:02+09:00
Subject: Re: Superclass of eigenclass

Joshua Ballanco wrote:
> On May 14, 2009, at 8:25 PM, J�rg W Mittag wrote:
>> Joshua Ballanco wrote:
>>> As it turns out, they can be very
>>> handy for implementing instance-specific methods,
>> Exactly. It is my understanding that they were only added as a place
>> to "stick" per-object methods. MRI already had classes, [...]
>>
>> AFAIK, the fact that they were exposed to the programmer is more of an
>> accident than a well-designed thought-out language feature.
> Right. So then the question: is there a compelling reason that they  
> should be allowed to be subclassed? (I mean, other than the obvious:  
> "Because that's not the way Ruby was designed" answer.) I cannot come  
> up with any compelling technical reason why the artificial limitation  
> of being unable to subclass "virtual classes"[1] should exist. I also  
> don't see what, besides this artificial limitation, is keeping Ruby  
> from having, at its heart, a fully prototype based inheritance system.

There are lots of areas in Ruby, where things aren't as simple,
orthogonal or consistent as they should be. Unfortunately[1],
simplicity, orthogonality or consistency are not in any way design
goals. I really like your idea, but you need to find a more compelling
argument than "it makes eigenclasses consistent with classes and
simplifies the object system". But a full-fledged prototype system
would be pretty cool.

jwm

[1] Or fortunately? After all, Brainfuck is certainly simple, 
    orthogonal and consistent ...