The die and warn functions both report the file and line number where the exception occurred. But if someone else is using your subroutine, they usually don't care where your code blew up. Instead, they want to know where their code invoked the subroutine. The the Carp manpage module provides alternative methods that report the exception from the caller's file and line number.

By default, this policy will not complain about die or warn, if it can determine that the message will always result in a terminal newline. Since perl suppresses file names and line numbers in this situation, it is assumed that no stack traces are desired either and none of the the Carp manpage functions are necessary.

    die "oops" if $explosion;             #not ok
    warn "Where? Where?!" if $tiger;      #not ok
    open my $mouth, '<', 'food'
        or die 'of starvation';           #not ok
    if (! $dentist_appointment) {
        warn "You have bad breath!\n";    #ok
    die "$clock not set.\n" if $no_time;  #ok
    my $message = "$clock not set.\n";
    die $message if $no_time;             #not ok, not obvious

If you give this policy an allow_messages_ending_with_newlines option in your .perlcriticrc with a false value, then this policy will disallow all uses of die and warn.

    allow_messages_ending_with_newlines = 0


the Carp::Always manpage


Jeffrey Ryan Thalhammer <thaljef@cpan.org>


Copyright (c) 2005-2007 Jeffrey Ryan Thalhammer. All rights reserved.

This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself. The full text of this license can be found in the LICENSE file included with this module.