Carp::Always(3) User Contributed Perl Documentation Carp::Always(3)

Carp::Always - Warns and dies noisily with stack backtraces

use Carp::Always;

Often used on the command line:

perl -MCarp::Always

This module is meant as a debugging aid. It can be used to make a script complain loudly with stack backtraces when warn()ing or die()ing.

Here are how stack backtraces produced by this module looks:

# it works for explicit die's and warn's
$ perl -MCarp::Always -e 'sub f { die "arghh" }; sub g { f }; g'
arghh at -e line 1
        main::f() called at -e line 1
        main::g() called at -e line 1
# it works for interpreter-thrown failures
$ perl -MCarp::Always -w -e 'sub f { $a = shift; @a = @$a };' \
                         -e 'sub g { f(undef) }; g'
Use of uninitialized value in array dereference at -e line 1
        main::f('undef') called at -e line 2
        main::g() called at -e line 2

In the implementation, the Carp module does the heavy work, through longmess(). The actual implementation sets the signal hooks $SIG{__WARN__} and $SIG{__DIE__} to emit the stack backtraces.

Also, all uses of "carp" and "croak" are made verbose, behaving like "cluck" and "confess".

Carp::Always implements the following methods.


Enables Carp::Always. Also triggered by statements like

use Carp::Always;
use Carp::Always 0.14;

but not by

use Carp::Always ();    # does not invoke import()


Disables Carp::Always. Also triggered with

no Carp::Always;

This module was born as a reaction to a release of Acme::JavaTrace by Sébastien Aperghis-Tramoni. Sébastien also has a newer module called Devel::SimpleTrace with the same code and fewer flame comments on docs. The pruning of the uselessly long docs of this module was prodded by Michael Schwern.

Schwern and others told me "the module name stinked" - it was called "Carp::Indeed". After thinking long and getting nowhere, I went with nuffin's suggestion and now it is called "Carp::Always".


Acme::JavaTrace and Devel::SimpleTrace




Carp::Always::SyntaxHighlightSource and Carp::Always::DieOnly

  • This module does not play well with other modules which fusses around with "warn", "die", $SIG{__WARN__}, $SIG{__DIE__}.
  • Test scripts are good. I should write more of these.

Please report bugs via GitHub

Backlog in CPAN RT:

Adriano Ferreira, <>

Copyright (C) 2005-2013, 2018 by Adriano Ferreira

This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself.

2023-07-25 perl v5.38.0