| Subject: | Usage of $` and $' |
The use of $` and $' will affect the performance of the entire script (not just this module),
please use something else instead of
$real_name = "<b>$`$'</b> ";
From http://perldoc.perl.org/perlre.html#Capture-buffers:
WARNING: Once Perl sees that you need one of $& , $` , or $' anywhere in the program, it has
to provide them for every pattern match. This may substantially slow your program. Perl uses
the same mechanism to produce $1 , $2 , etc, so you also pay a price for each pattern that
contains capturing parentheses. (To avoid this cost while retaining the grouping behaviour,
use the extended regular expression (?: ... ) instead.) But if you never use $& , $` or $' , then
patterns without capturing parentheses will not be penalized. So avoid $& , $' , and $` if you
can, but if you can't (and some algorithms really appreciate them), once you've used them
once, use them at will, because you've already paid the price. As of 5.005, $& is not so costly
as the other two.
As a workaround for this problem, Perl 5.10.0 introduces ${^PREMATCH} , ${^MATCH} and
${^POSTMATCH} , which are equivalent to $` , $& and $' , except that they are only
guaranteed to be defined after a successful match that was executed with the /p (preserve)
modifier. The use of these variables incurs no global performance penalty, unlike their
punctuation char equivalents, however at the trade-off that you have to tell perl when you
want to use them.