Re: how does "1 while $scalar =~ s/(%A .*)\n%A /$1\;/g;" work?

[Jeff 'japhy/Marillion' Pinyan]

On Aug 13, ERIC Lawson - x52010 said:

>Given that "1 while ..." logic works for my needs here, though, is there a
>reason I should use the sexeger logic instead?  Is the "1 while ..."
>expression more costly?  It seems, on the face of it, that the "1
>while" is more readily decypherable by another programmer unfamiliar with
>my coding style.  

You have to beware of telescoping substitutions (done via the 1 while
s///g construct) that are recursive.  Here's an example:

  %trans = ( 'man' => 'good man', 'good' => 'nice' );
  $re = join '|', map quotemeta, keys %trans;

  $text = "you're a good man";
  1 while $text =~ s/\b($re)\b/$trans{$1}/g;

The first time around, that produces "you're a nice good man".  On the
second time, it produces "you're a nice nice good man".  And so on.

That's just a general caveat of the 1 while s///g approach.

>That perception, of the relative opacity of the sexeger, may be mistaken,
>of course, and is at best a subjective judgement, so I wouldn't attach
>much weight to it, given any substantial reason favoring the sexeger
>expression as compared to the "1 while" expression.

Um, you might not want to use the sexeger approach if you're not
comfortable with it.  Or you might want to comment it, and let other
readers (like yourself) know what you're doing.

-- 
Jeff "japhy" Pinyan      [EMAIL PROTECTED]      http://www.pobox.com/~japhy/
RPI Acacia brother #734   http://www.perlmonks.org/   http://www.cpan.org/
** Look for "Regular Expressions in Perl" published by Manning, in 2002 **


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