From: Rick DeNatale <rick.denatale@...>
Date: 2008-09-18T21:44:23+09:00
Subject: Re: Preserve insert order in a Hash

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On Thu, Sep 18, 2008 at 6:28 AM, Yukihiro Matsumoto <matz@ruby-lang.org>wrote:

> Hi,
>
> In message "Re: Preserve insert order in a Hash"
>     on Thu, 18 Sep 2008 18:54:20 +0900, "Thomas B." <tpreal@gmail.com>
> writes:
>
> |Could anybody explain why this feature was added?
>
> Useful for some cases, especially for keyword arguments.
>
> |Isn't it going to slow down the operations on the Hash?
>
> No. hash reference operation does not touch order information, only
> for iteration.  Memory consumption increased a bit.
>

If I remember correctly, it's been a while since I looked at the code, 1.9
implements this by using a singly linked list which introduces a small
overhead only when elements are either added or deleted.

-- 
Rick DeNatale

My blog on Ruby
http://talklikeaduck.denhaven2.com/

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