From: dblack@...
Date: 2006-03-12T22:44:07+09:00
Subject: Re: Help me understand why the Ruby block is slower than wit

Hi --

On Sun, 12 Mar 2006, James Edward Gray II wrote:

> On Mar 11, 2006, at 9:58 AM, Alan Burch wrote:
>
>> James Gray wrote:
>>> On Mar 10, 2006, at 4:57 PM, Alan Burch wrote:
>>> 
>>>> I first saw
>>>> that the array class mixed in enumerable and that I could use the to_a
>>>> call from there, but a quick check using -r profile showed that my
>>>> original call to split was a much quicker way to convert from a string
>>>> to an array.
>>> 
>>> This sounds like premature optimization.  Remember, you start
>>> worrying about speed when the code gets too slow.  Not before.
>>> 
>>> James Edward Gray II
>> 
>> James:
>> I'm going to have to respectfully disagree.
>
> Well, I'm pretty darn sure you are in the minority on that one:  ;)
>
> http://www.google.com/search?q=%22premature+optimization%22

But one doesn't want to suppress one's knowledge.  When I write a
program, if I happen to know that, say:

   puts a

will run faster than:

   eval "puts #{97.chr}"

then I can't really be blamed for using that knowledge, just because
the knowledge pertains to speed.

In other words, I don't think that avoiding premature optimization
means that one should never knowingly take speed into account when
choosing what to put in one's code.  In fact, I would find it really
difficult to do that, because I wouldn't know how to choose among the
various alternatives available in a way that paid no attention to
execution speed.

This isn't an argument in favor of premature optimization; rather, I'm
suggesting that having and using some rough-cut knowledge of execution
speed (as between, say, split and unpack, or something like that)
isn't premature :-)  Nor is it optimization; it's really melioration.


David

-- 
David A. Black (dblack@wobblini.net)
Ruby Power and Light, LLC (http://www.rubypowerandlight.com)

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