[log4perl-devel] Good use of the $logger->log() method

[Meir G. <me...@gu...>]

Dear logging folks,

First thank you for a very useful and comprehensive logging package.

I have though an issue with one passage in the documentation. In the CPAN page Log::Log4perl (Ver. 1.37) (http://search.cpan.org/~mschilli/Log-Log4perl-1.37/lib/Log/Log4perl.pm) one can read the following:

    Instead of calling the methods

        $logger->trace("...");  # Log a trace message
        ... (other variants deleted)

    you could also call the log() method with the appropriate level using the constants defined in Log::Log4perl::Level:

        use Log::Log4perl::Level;

        $logger->log($TRACE, "...");
        ... (other variants deleted)

    But *** nobody does that, really ***. (my enhancement - MG) Neither
    does anyone need more logging levels than these predefined ones. If
    you think you do, I would suggest you look into steering your logging
    behavior via the category mechanism.

Well, I found at least one use for the $logger->log() method: dynamic level logging.

Take for example a "system()" call. It can return a number of exit codes by issuing something like «exit(0x2C);» command. I find it very convenient to segregate on the basis of the return code what logging level to assign to the log message upon returning:

    my %exit_level = (
      0 => $INFO,
      1 => $WARN,
      2 => $WARN,
      4 => $ERROR,
      0xFF => $FATAL,
      );

    My %message = (
      0 => "Message 1",
      1 => "..."
      ...
      );

    my $result = system ('perl', 'my_script.pl, @args) >>= 8;

    $logger->log($exit_level{$result}, $message{$result});

So, I would recommend a change in the doc showing such an example.

Meir