From: Kero <kero@...>
Date: 2006-07-26T00:30:07+09:00
Subject: Re: Hash order bug?

[snip]
>>>> What's happening? all my code is behaving wrong because of that.
>>> 
>>> Hashes are unordered.  If you need an ordered collection, you'll need
>>> to use an array.
>>
>> Oh my god, i didn't know it, sorry. Is that a missing feature?
>
> Debate rages on this point :-)  It's mostly a speed issue, I think.
> At least my memory is that Matz's latest statement was to the effect
> that he would do it if it could be done efficiently.
> 
> The question came up during a lunch here at OSCON (with me, Jim
> Weirich, Pat Eyler, and a fellow named Nicolas whose last name I'm
> afraid I don't remember) as to whether making hashes ordered in a
> future Ruby would break any existing code.  I think the answer is no,
> which is kind of interesting considering what a major change it would
> be.  It's a case where the feature would be purely additive.

I guess there won't be many ppl using algorithms that use the *un*sorted
aspect of a Hash. Using Kernel#rand instead of Object#hash seems
better. printing a few hash-values suggest they're not that random anyway...

Other than that, would you sort the hash (or iterator) on its keys, its
values or insertion sequence?

NB: why did I read "addictive" at first pass? The question has been raised
more often; and I admit I have overridden Hash#keys (and Hash each_pair,
iirc) to achieve a (partially) sorted effect... The problem is that you can
not generally sort keys (specifically not symbols).