From: Patrick May <patrick@...>
Date: 2004-09-04T12:51:30+09:00
Subject: Re: Hashes and ordering


On Friday, September 3, 2004, at 11:39  PM, Hal Fulton wrote:

> Markus wrote:
>> Where are you going with this?  There seem to be three unrelated 
>> things
>> here:
>
> Well, I have been thinking along the lines of: What if we had a 
> built-in
> ordered indexable collection in Ruby?
>
>> To see why this seems odd, let me recast your question in terms of
>> arrays:
>> <analogy>
>
> [snip]
>
> Clever analogy, but you're presupposing an unordered arbitrarily 
> indexable
> collection. A hash, like our Hash, is inherently unordered, but I am
> imagining a similar ordered data structure.
>
> It's more like:
>
>   x = [1,2]
>   y = [2,1]
>   x == y     # false - we *do* depend on this being false
>
> I'm envisioning a data structure that has an order, but is otherwise 
> (in
> behavior, not implementation) like our current Hash.
>
> I don't want to go into detail about what I'm thinking at the moment.
>
> But I can see where my post was unclear or vague and would raise
> very valid questions in your mind.

php's arrays are like this:

     http://www.php.net/manual/en/language.types.array.php

They are pretty useful primitives.  I wouldn't mind having one of these 
in ruby :-)

Cheers,

Patrick