package AB; # File: /Users/moo/AB.pm
use strict;
use Path::Tiny;
sub ohai { __FILE__ }
sub ohai_der { path(__FILE__)->absolute }
1;

##</code><code>##

moo@cow[54]~>perl -MAB -le 'print AB->ohai; print AB->ohai_der'
AB.pm
/Users/moo/AB.pm

##</code><code>##

moo@cow[55]~>perl -MAB -le 'chdir "/tmp"; print AB->ohai; print AB->ohai_der;'
AB.pm
/private/tmp/AB.pm