From: "David A. Black" <dblack@...>
Date: 2005-07-07T11:11:42+09:00
Subject: Re: Inheriting Array and slice() behaviour

Hi --

On Thu, 7 Jul 2005, Sylvain Joyeux wrote:

> This is a lisp-like language, so expressions are basically array of atoms
> and expressions. When I do a slice() this is to get a subset of the list,
> but a subset is not an expression itself.

Expressions may be arrays or lists of atoms and expressions in a
sense, but they're not actually instances of the Ruby class Array.

> Expression is-a Array, but Expression.slice is just an Array

That's true, by definition, if you decide up front that a slice operation
has to return an Array object.  I don't think I would, though.  I'd
actually tend to think of a "slice" of something as being "cut from
the same cloth" (i.e., of the same class) as the original -- as
opposed to, say, the results of a map operation, where you're
transforming elements and then need a general-purpose container (an
array) to store them in.


David

-- 
David A. Black
dblack@wobblini.net