From: Eric Hodel <drbrain@...7.net>
Date: 2005-02-16T14:29:31+09:00
Subject: Re: Curious regexp behavior

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On 15 Feb 2005, at 17:16, Derek Lewis wrote:

> First one:
>
> total = 0
> File.open( 'words', 'r' ) { |file|
>    file.each_line { |line|
> 		word = line.chomp
> 		total +=1 if word =~ /[a-df-h][aeiou]{2}/
                               ^^^^ inline regexp (part of the AST)
> 	}
> }
> puts total
>
> Second one:
>
> rexp = /[a-df-h][aeiou]{2}/
> total = 0
> File.open( 'words', 'r' ) { |file|
>    file.each_line { |line|
> 		word = line.chomp
> 		total +=1 if word =~ rexp
                              ^^^^ variable lookup
> 	}
> }
> puts total
>
>
> I expected the second one to be slightly faster, but was surprised to
> see that it was actually slightly slower.  I ran each one about 10-15
> times, and eyeballed an average.  The results from each run after the
> first were pretty consistant.
>
> It's just a curiosity, but does anyone know what might cause them to be
> 'backwards' like that? :)

Inline regexps are much faster than a variable lookup then using the 
methods on the Regexp object.

-- 
Eric Hodel - drbrain@segment7.net - http://segment7.net
FEC2 57F1 D465 EB15 5D6E  7C11 332A 551C 796C 9F04

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