The special tokens __FILE__ and __LINE__ report the filename and line number of the current source file you're in. They do not interpolate into quoted strings, though.
Jeff japhy Pinyan,
P.L., P.M., P.O.D, X.S.:
Perl,
regex,
and perlhacker How can we ever be the sold short or the cheated, we who for every service have long ago been overpaid? ~~ Meister Eckhart