From: Jeremy Kemper <jeremy@...>
Date: 2009-11-10T15:44:15+09:00
Subject: [ruby-core:26659] Re: HashWithIndifferentAccess to core

On Sun, Nov 8, 2009 at 7:06 AM, Nobuyoshi Nakada <nobu@ruby-lang.org> wrote:
> Hi,
>
> At Sun, 8 Nov 2009 12:25:54 +0900,
> Yusuke ENDOH wrote in [ruby-core:26612]:
>> > I've been toying with allowing custom hashing from the Ruby side for the
>> > past 2 days and have a semi-functional version (patch attached against
>> > subversion trunk 25671 - http://gist.github.com/228773)
>>
>> Unfortunately, your patch has a serious problem; it lets RHash have
>> four VALUEs, which makes any object require 24 bytes (traditionally
>> 20 bytes) in 32 bit envirionment.
>
> I don't think that index_with object is necessary, why the hash
> itself can't have such methods?

I really like this customized behavior. It can be used more
generically, for example to optimize Rack's very slow HeaderHash.

It's slower than Lourens' original patch, though:

                             user     system      total        real
naude #[:abc]            0.050000   0.000000   0.050000 (  0.052469)
nobu  #[:abc]            0.140000   0.000000   0.140000 (  0.144207)
rails #[:abc]            0.280000   0.000000   0.280000 (  0.287421)
naude #["ab"]            0.080000   0.000000   0.080000 (  0.080840)
nobu  #["ab"]            0.140000   0.000000   0.140000 (  0.135914)
rails #["ab"]            0.070000   0.000000   0.070000 (  0.078379)

Benchmark at http://github.com/jeremy/rails/blob/hwia/activesupport/hwia.rb

jeremy