package Your::Forager;
use base 'Badger::Base';
use constant DEBUG => 0;

our $MESSAGES = {
    foraging => 'Foraging in the %s for %s',

sub forage {
    my ($self, $where, $what) = @_;
    $self->debug_msg( foraging => $where, $what ) if DEBUG;
    # ... do some foraging...
Thus Spake Andy:

If you set a DEBUG constant instead then Perl is smart enough to optimise away the entire debugging line when it compiles the program. The upshot is that there's is no runtime overhead whatsoever with these kind of debugging statements. The downside is that you have to go and edit the source code to change 0 to 1 when you want to enable debugging. Or do you?....