log4perl-devel

[log4perl-devel] Small issue with Log::Log4perl 1.15

[Emil J. <ej...@gm...>]

Hi,

With the latest version 1.15, in a specific scenario, warning messages
are printed on the standard error.
It was not happening with 1.14 and before.

Here is a test case:

------------------------------------------------------------------------------------
$ cat tst_log.pl
#!/usr/bin/perl

use strict;
use Log::Log4perl qw(get_logger :levels);

my $config_file = 'logger.conf';

Log::Log4perl->init($config_file);

my $logger = get_logger(undef);

$logger->info('info_message_1');

exit;
$ tst_log.pl
Use of uninitialized value in string eq at
/usr/local/share/perl/5.8.8/Log/Log4perl.pm line 360.
Use of uninitialized value in string eq at
/usr/local/share/perl/5.8.8/Log/Log4perl/Logger.pm line 560.
$ cat t.log
2008/02/20 16:04:11 INFO> tst_log.pl:12 main:: - info_message_1
$
------------------------------------------------------------------------------------

Test script and the configuration file are attached.

Aside the messages on the STDERR, functionality is not affected.

Thanks in advance,
Emil

-- 
Emil Janev

Re: [log4perl-devel] Small issue with Log::Log4perl 1.15

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

On Wed, 20 Feb 2008, Emil Janev wrote:

> my $logger = get_logger(undef);

That's an interesting case. While

      # get a logger for the current package
    get_logger()

and

      # get the root logger
    get_logger("")

are defined cases, using 'undef' as in

    get_logger( undef )

isn't defined. There was a change in 1.15 that now brings this undefined
behavior to light (unfortunately for you :).

If you want to use a variable to toggle between "" and the empty list,
use an array:

    my @array = ();
    my $logger = get_logger(@array);

    # vs.

    my @array = ("");
    my $logger = get_logger(@array);

Does that work for you?

-- Mike

Mike Schilli
m...@pe...

Re: [log4perl-devel] Small issue with Log::Log4perl 1.15

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

On Thu, 21 Feb 2008, Emil Janev wrote:

> The problem certainly can be fixed with providing a default value of
> this parameter of an empty string,
> if an 'undef' value gets trough.

Passing on the arg list from the wrapper to the Log4perl log call is
probably the easiest solution:

    sub wrapper_get_logger {
        ...
        my $logger = get_logger(@_);
        ...
    }

> My question is also if there is any planned future change, where undef
> case will be treated in the same way as the one with an empty string,
> or an empty array.

It's not really obvious to me what 'undef' should stand for -- maybe
we'll leave it undefined until someone has a smart idea.

> p.s. As a coincidence, these days reading the Linux Pro Magazine on the
> subway ride to/from work,
>         I came upon the 2007-12 article "I think in Perl' :)

It's even available online if anybody is interested what I'm doing when
I'm not working on Log4perl :)

    http://w3.linux-magazine.com/issue/85/Perlmeister_Michael_Schilli.pdf

-- Mike

Mike Schilli
m...@pe...

> >> my $logger = get_logger(undef);
> >>
> >
> > That's an interesting case. While
> >
> >       # get a logger for the current package
> >     get_logger()
> >
> > and
> >
> >       # get the root logger
> >     get_logger("")
> >
> > are defined cases, using 'undef' as in
> >
> >     get_logger( undef )
> >
> > isn't defined. There was a change in 1.15 that now brings this undefined
> > behavior to light (unfortunately for you :).
> >
> > If you want to use a variable to toggle between "" and the empty list,
> > use an array:
> >
> >     my @array = ();
> >     my $logger = get_logger(@array);
> >
> >     # vs.
> >
> >     my @array = ("");
> >     my $logger = get_logger(@array);
> >
> > Does that work for you?
> >
> > -- Mike
> >
> > Mike Schilli
> > m...@pe...
> >
>
>
> --
> Emil Janev
>
>