[Melbourne-pm] Just how much does $& slow things down?

Alfie John alfiejohn at gmail.com
Thu Nov 20 19:25:19 PST 2008

>From perlre:

WARNING: Once Perl sees that you need one of $&, $', or $' anywhere in
       the program, it has to provide them for every pattern match.  This
       substantially slow your program.

This is the only place in the whole program which uses a regex, so the
> impact on other parts of the program should be nil.
> I just don't know if it's going to be worth removing those references to
> $&, and how much it will benefit the running of the program.
> Obviously, the bigger @an_array is, the larger the impact, but I can safely
> say it won't be much bigger than about 50.
> So, are we talking an order of magnitude slower? More? Less? Anybody even
> want to take an educated guess?

In other words, having it only in the above code will still impact *all
other* regexes in any code, including all imported modules.

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