From: William Morgan <wmorgan-ruby-talk@...>
Date: 2005-07-07T01:05:35+09:00
Subject: Re: Inheriting Array and slice() behaviour

Excerpts from Sylvain Joyeux's mail of  6 Jul 2005 (EDT):
> I have a class inheriting Array, and I expected slice() and [] 
> to return Array objects. Unfortunately
[...]
> Moreover, since my Expression class has instance variables, the instance 
> produced by slice() does not have it anymore (which is bad)

It looks like [], slice and slice! methods create a new instance of the
objects class as the return value, but don't initialize it---so any
instance variables will be nil (rb_ary_subseq). I agree that this is
weird.

> I wokarounded this by using Delegator

What return type do you want? Arrays or Expressions? You can force
return values back to Arrays with #to_a, or manually make Expressions
with something like

  y = Expression.new(x.slice(1..5).to_a)

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