From: Roger Pack <rogerpack2005@...>
Date: 2008-09-05T00:13:52+09:00
Subject: Re: Hash optimization question

> I guess it will be difficult to get both: fast hash lookup and
> insertion on one hand and fast iteration on the other hand.  Is it
> worth the effort?  I don't know.  This depends on your application.
> Where is this a problem for you?  Maybe there is a more efficient data
> structure for your particular problem.

Yeah I guess it's hard to have the best of both worlds. Hmm.  I suppose 
that for small hashes which call .each a fix would definitely help, for 
large hashes that call .each "a lot" it would probably also be quicker, 
and for any hashes which don't call .each it wouldn't be helpful. I 
wonder if the slowdown is small enough to make it worth it anyway 
[though it would use more RAM too--then again, Ruby isn't known for its 
low memory usage] :)

In the example I was thinking of, I was using a hash to parse lines in a 
file

a la

identifiers = {/abc/ => 'an abc line', /def/ => 'a def line'}

string.each_line {|l| identifiers.each{|reg, description| if l =~ reg 
then; do something; end }

So...my particular example I'm only using a hash because of the clean 
syntactic look :) [not for the functionality at all].

Rails uses it quite a bit, too, hence my enquiring about it.

I think that for now I'll just write a Hash monkey patcher a la

a = {}
a.fast_each_ify
a[:abc] = :def # elements from here on are now wrapped internally to 
allow for a quicker .each

Thanks!
-=R
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