From: Hal Fulton <hal9000@...>
Date: 2004-12-03T08:43:27+09:00
Subject: Re: ordered hash ?

Robert Klemme wrote:
> "itsme213" <itsme213@hotmail.com> schrieb im Newsbeitrag
> news:Mptrd.59198$KQ2.38410@fe2.texas.rr.com...
> 
>>Is there a pure-ruby ordered hash? I'm looking for something that will
>>preserve the order in which key/value pairs were entered. The one on RAA
> 
> is
> 
>>buggy http://raa.ruby-lang.org/project/orderedhash/
> 
> 
> Whenever I hear "ordered hash" then I think of a hash whose keys are
> ordered according to a definable order - not necessarily insertion order.
> In fact, insertion order seems to me a very special case.  Is this really
> widely used?
> 

I'll reply to this, since an ordered hash is on my wish list.

First of all, if it HAS an order, then it can be sorted (reordered)
in any way you want. The (first) important thing to me is that it
HAVE an order.

Secondly, insertion order should IMO be the default -- because of
hash literals, if for no other reason.

If I say {this=>1, that=>2, other=>3} then that is what I expect
(assuming there is any order at all). I would not want my hash
literals scrambled (assuming some ordering, but one not based on
insertion).

But as long as a hash HAS an order, you can order it any way you
like -- just as we can sort an array any way we like.

And yes, I know there are fundamental differences between hashes
and arrays. ;)


Hal