From: William Morgan <wmorgan-ruby-talk@...>
Date: 2005-07-07T07:54:17+09:00
Subject: Re: Inheriting Array and slice() behaviour

Excerpts from Yukihiro Matsumoto's mail of  6 Jul 2005 (EDT):
> on Wed, 6 Jul 2005 18:17:21 +0900, Sylvain Joyeux
> <sylvain.joyeux@polytechnique.org> writes:
> 
> |I have a class inheriting Array, and I expected slice() and [] |to
> return Array objects.
> 
> Why?  I'd expect them to return instances of the class of the
> receiver, as Daniel does in [ruby-talk:147323], since they are ripped
> part of the receiver.

But #+ returns an Array. Is that consistent?

Like the OP, I think it's weird and special-cased to have #slice
magically return something with the receiver's class. Especially since
the return value is going to be broken (not initialized) except in
trivial cases.

> Anyway, I'd suggest you not to subclass basic classes, unless you are
> sure what you're doing.  I don't think Expressions by no means have
> is-a relationship to Arrays.  Inheritance is not a panacea.

Absolutely.

-- 
William <wmorgan-ruby-talk@masanjin.net>