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


Carp-Always documentation Contained in the Carp-Always distribution.

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NAME

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

SYNOPSIS

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  use Carp::Always;

makes every warn() and die() complains loudly in the calling package and elsewhere. More often used on the command line:

  perl -MCarp::Always script.pl

DESCRIPTION

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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.

Oh, by the way, carp and croak when requiring/using the Carp module are also made verbose, behaving like cloak and confess, respectively.

EXPORT

Nothing at all is exported.

ACKNOWLEDGMENTS

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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 were prodded by Michael Schwern.

Schwern and others told me "the module name stinked" - it was called Carp::Indeed. After thinking long and not getting nowhere, I went with nuffin's suggestion and now it is called Carp::Always. Carp::Indeed which is now deprecate lives in its own distribution (which won't go anywhere but will stay there as a redirection to this module).

SEE ALSO

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Please report bugs via CPAN RT http://rt.cpan.org/NoAuth/Bugs.html?Dist=Carp-Always.

BUGS

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Every (un)deserving module has its own pet bugs.

AUTHOR

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Adriano Ferreira, <ferreira@cpan.org>

COPYRIGHT AND LICENSE

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Carp-Always documentation Contained in the Carp-Always distribution.

package Carp::Always;

use 5.006;
use strict;
use warnings;

our $VERSION = '0.09';

use Carp qw(verbose); # makes carp() cluck and croak() confess

sub _warn {
  if ($_[-1] =~ /\n$/s) {
    my $arg = pop @_;
    $arg =~ s/ at .*? line .*?\n$//s;
    push @_, $arg;
  }
  warn &Carp::longmess;
}

sub _die {
  if ($_[-1] =~ /\n$/s) {
    my $arg = pop @_;
    $arg =~ s/ at .*? line .*?\n$//s;
    push @_, $arg;
  }
  die &Carp::longmess;
}

my %OLD_SIG;

BEGIN {
  @OLD_SIG{qw(__DIE__ __WARN__)} = @SIG{qw(__DIE__ __WARN__)};
  $SIG{__DIE__} = \&_die;
  $SIG{__WARN__} = \&_warn;
}

END {
  @SIG{qw(__DIE__ __WARN__)} = @OLD_SIG{qw(__DIE__ __WARN__)};
}

1;
__END__