log4perl-devel

[log4perl-devel] Calling get_logger from DESTROY breaks exception handlng

[Maciej W. <mac...@li...>]

Hello Log4Perl team!

I have experienced this problem since version 0.32 of Log4Perl. The effec=
t =20
is exactly the same on Linux, AIX or Windows with Perl 5.6 or Perl 5.8 so=
 =20
I will not give exact platform specification.
Run this code to reproduce the problem:

#!/usr/bin/perl

package Base;
use Log::Log4perl qw(get_logger);
sub new {
	return bless {}, shift;
}
sub DESTROY {
	get_logger;
}
1;

eval {
	my $b =3D Base->new;
	die "this is the exception";
};

if ($@) {
	print "Caught exception: >$@<\n";
} else {
	print "No exception\n";
}

You can see that the $@ variable is empty. It happens if the get_logger =20
subroutine is called from the DESTROY method when an objects is going out=
 =20
of scope. No DESTROY or no get_logger and the program works fine. I am =20
very curious what is wrong here.

Please reply to my private mailbox too as I do not subscribe to this list=
.
--
Maciej Walezak

Re: [log4perl-devel] Calling get_logger from DESTROY breaks exception handlng

[Mike S. <m...@pe...>]

Maciej Walezak wrote on 6/8/2004, 6:58 AM:

 > You can see that the $@ variable is empty. It happens if the get_logger
 > subroutine is called from the DESTROY method when an objects is going
 > out
 > of scope. No DESTROY or no get_logger and the program works fine. I am
 > very curious what is wrong here.

I don't think this is related to Log4perl. You can reproduce the same 
effect using

     sub DESTROY {
         #get_logger;
         $@ = undef;
     }

If you run code in DESTROY (which gets triggered while leaving the eval 
{ } block because your object goes out of scope) that's resetting $@, 
you'll get this weird behaviour. If you still want this code to be 
called, just localize $@:

    sub DESTROY {
         #get_logger;
         local $@;
         $@ = undef;
     }

--
-- Mike
Mike Schilli
m...@pe...


 > Hello Log4Perl team!
 >
 > I have experienced this problem since version 0.32 of Log4Perl. The
 > effect
 > is exactly the same on Linux, AIX or Windows with Perl 5.6 or Perl 5.8
 > so
 > I will not give exact platform specification.
 > Run this code to reproduce the problem:
 >
 > #!/usr/bin/perl
 >
 > package Base;
 > use Log::Log4perl qw(get_logger);
 > sub new {
 >     return bless {}, shift;
 > }
 > sub DESTROY {
 >     get_logger;
 > }
 > 1;
 >
 > eval {
 >     my $b = Base->new;
 >     die "this is the exception";
 > };
 >
 > if ($@) {
 >     print "Caught exception: >$@<\n";
 > } else {
 >     print "No exception\n";
 > }
 >
 > You can see that the $@ variable is empty. It happens if the get_logger
 > subroutine is called from the DESTROY method when an objects is going
 > out
 > of scope. No DESTROY or no get_logger and the program works fine. I am
 > very curious what is wrong here.
 >
 > Please reply to my private mailbox too as I do not subscribe to this
 > list.
 > --
 > Maciej Walezak