Re: Interpolation in character class

merlyn is right (as he almost always is). However, this sounds like a good case for negative look-behind.

$msg =~ /(\A$dle)(?<!\1)/;
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We are the carpenters and bricklayers of the Information Age.

The idea is a little like C++ templates, except not quite so brain-meltingly complicated. -- TheDamian, Exegesis 6

Please remember that I'm crufty and crochety. All opinions are purely mine and all code is untested, unless otherwise specified.

Comment on Re: Interpolation in character class Download Code

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Re: Re: Interpolation in character class by Anonymous Monk on Oct 02, 2003 at 17:48 UTC
That seems to generate a "variable length lookbehind not implemented" error :( Also, I don't understand why we are looking behind, don't we want to test the second string character with look ahead ? If so, how do we confine the lookahead test to only the next character ? Doesn't it look all the way to the end of the string ? Thanks, Scott.	[reply]
Re: Re: Re: Interpolation in character class by dragonchild (Archbishop) on Oct 02, 2003 at 18:01 UTC
That'll teach me to blab about features I don't know without testing them first. Yes, positive lookahead would definitely be possible. You'd have to flip your test, though. `$x = 'aba'; print $x =~ /(.)(?=\1)/ ? "double!\n" : "not double!\n"; $x = 'abba'; print $x =~ /(.)(?=\1)/ ? "double!\n" : "not double!\n"; ---- not double! double!` [download] ------ We are the carpenters and bricklayers of the Information Age. The idea is a little like C++ templates, except not quite so brain-meltingly complicated. -- TheDamian, Exegesis 6 Please remember that I'm crufty and crochety. All opinions are purely mine and all code is untested, unless otherwise specified.	[reply] [d/l]