From: Robert Feldt <feldt@...>
Date: 2001-11-30T14:56:40+09:00
Subject: [ruby-talk:27031] Re: thoughts on virtual base classes, interfaces

On Fri, 30 Nov 2001, Dave Thomas wrote:

> > I tend to use an "abstract base class" with raise NotImplementedError to
> > document this. Not for Ruby's sake but as documentation. A smart doc tool
> > would parse it out and call the class and interface and mark the method as
> > "virtual" or whatever it should be called.
> 
> Would a mixin perhaps be a better flag of this?
> 
Sometimes yes, but I (1) often find it hard to invent a good name
ending with -able (:-)) and (2) sometimes want the subclasses really be
subclasses of a certain class and not only implement an interface. I think
I mean that the decision to use a Mix-in or Super class cannot be made
based on the aspect discussed here alone.

On the other hand I don't have a clear-cut way to choose between a Mix-in
or a Super class. Any can share their heuristics? Most flexible is often
to only use Mix-ins, I guess? I would think an answer to this question
suitable for the FAQ since its likely to be an issue for newcomers
learning about the Module/Class dicothomy and their uses.

Regards,

/RobertF