An idiom I learned from an ingy module, almost certainly Pegex, is: 
use constant DEBUG => $ENV{MY_DEBUG};
# ...
DEBUG and print "something\n";

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The benefit is that constant-folding means that if it's not in debug mode, the Perl interpreter will simply optimise the debugging code out entirely.

In reply to Re: Best practice for handling subroutines that are conditionally loaded? by etj
in thread Best practice for handling subroutines that are conditionally loaded? by nysus

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