http://qs1969.pair.com?node_id=31691

Item Description: Apply a filter to a filehandle! Written by our own btrott

Review Synopsis:

Filter::Handle

This module was originally written here at the Perl Monks Monastery. It provides a simple interface allowing users to tie a filter subroutine to a filehandle. There are many things you could do with this... from labeling STDERR output as STDERR output to easily puting line numbers and timestamps in a logfile.