Marcello has asked for the wisdom of the Perl Monks concerning the following question:

Hello,

In all my modules I use $SIG{__WARN__} to log warnings in a logfile. This ensures warnings are never overlooked. However, it seems some warnings cannot be caught: 

package Test;

use strict;
use warnings;

sub new {
    my $this = shift;
    my $class = ref($this) || $this;
    my $self = {};
    bless($self, $class);

    $SIG{'__WARN__'} = sub { print 'WARNING: '.$_[0]; };

    return $self;
}

sub A {
    my $self = shift;

    warn 'This will trigger $SIG{__WARN__}';
}

sub B {
    my $self = shift;

    $self->NonExistingFunction();
}

my $test = Test->new();
$test->A();
$test->B();

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The output is: 

WARNING: This will trigger $SIG{__WARN__} at test.pl line 20.
Can't locate object method "NonExistingFunction" via package "Test" at
+ test.pl line 26.

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So the fatal error triggered when calling a non-existing method is not caught.

How can I accomplish this?

Best regards,

Marcel

Replies are listed 'Best First'.
Re: Catching warnings
by friedo (Prior) on Dec 13, 2005 at 18:45 UTC
    That's not a warning, that's a fatal error. If you want to catch fatal errors, there's a few things you can do:

    1. Put a handler in $SIG{__DIE__}. You will get the fatal error message but the program will still die. (Unless you do some extra work. See the perlvar entry on %SIG for details.)

    2. Wrap your possible fatality-producing code in an eval. Any fatal error will be put in $@ which you can send to your logging function. For example: 

    eval { 
    $self->NonExistingFunction();
};

print "FATAL ERROR: $@" if $@;

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      Thanks,

      $SIG{__DIE__} did the trick.

      Marcel
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