From: Robert Dober <robert.dober@...>
Date: 2006-08-21T19:26:10+09:00
Subject: Re: Why Does Hash Apparently Reorder Its Internal Representation And Other Associated Ponderings

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On 8/21/06, Yukihiro Matsumoto <matz@ruby-lang.org> wrote:
>
> Hi,
>
> In message "Re: Why Does Hash Apparently Reorder Its Internal
> Representation And  Other Associated Ponderings"
>     on Mon, 21 Aug 2006 16:37:00 +0900, Hal Fulton <
> hal9000@hypermetrics.com> writes:
>
> |Personally I favor introducing an ordered hash of some form into Ruby.
> |Other people don't. Many want the original Hash kept as it is for speed
> |(though I am still unconvinced that merely keeping a sequence number
> |along with each key would impact speed dramatically).
>
> I am open to introduce order into 1.9 Hash, as long as we can
> accomplish reasonable performance.  I haven't yet read the "A use case
> for an ordered hash" thread yet.  I am facing a huge mountain of mails
> after the vacation.
>
>                                                         matz.
>
>
Honestly I would prefer a subclass and Mixins allowing to define the order
of retrieval.
As a matter of fact that is the only "order definition" that makes sense to
me

Now as it comes to implementation of course there must be a price to pay,
either on ordered access or on storage. So I agree with the others who
pointed out they are not willing to pay that price.
Hash is for fast lookup after all.
But having a subclass or a mixin for ordered hash access in the ruby core
would be *great*!!!

I am just dreaming:

ohhhhhh =3D OrderedHash.new { |k1,k2| tell_my_friend_what_order_is(k1, k2) =
}

class MyOH < OrderedHash
       def key_order(k1, k2)  ### Here we could define Mixins for common ke=
y
orders

And would asking for having two like the following be too much?

class FastOrderdHash (key order is stored in an AST e.g.)
class SlimOrderedHash (keys are sorted on ordered access only)

just my micromoney worth

Cheers
Robert

--=20
Deux choses sont infinies : l'univers et la b=EAtise humaine ; en ce qui
concerne l'univers, je n'en ai pas acquis la certitude absolue.

- Albert Einstein

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