Level

Section: User Contributed Perl Documentation (3)
Updated: 2021-02-08
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NAME

Log::Log4perl::Level - Predefined log levels

SYNOPSIS

  use Log::Log4perl::Level;
  print $ERROR, "\n";

  # -- or --

  use Log::Log4perl qw(:levels);
  print $ERROR, "\n";

DESCRIPTION

"Log::Log4perl::Level" simply exports a predefined set of Log4perl log levels into the caller's name space. It is used internally by "Log::Log4perl". The following scalars are defined:

    $OFF
    $FATAL
    $ERROR
    $WARN
    $INFO
    $DEBUG
    $TRACE
    $ALL

"Log::Log4perl" also exports these constants into the caller's namespace if you pull it in providing the ":levels" tag:

    use Log::Log4perl qw(:levels);

This is the preferred way, there's usually no need to call "Log::Log4perl::Level" explicitly.

The numerical values assigned to these constants are purely virtual, only used by Log::Log4perl internally and can change at any time, so please don't make any assumptions. You can test for numerical equality by directly comparing two level values, that's ok:

    if( get_logger()->level() == $DEBUG ) {
        print "The logger's level is DEBUG\n";
    }

But if you want to figure out which of two levels is more verbose, use Log4perl's own comparator:

    if( Log::Log4perl::Level::isGreaterOrEqual( $level1, $level2 ) ) {
        print Log::Log4perl::Level::to_level( $level1 ), 
            " is equal or more verbose than ", 
            Log::Log4perl::Level::to_level( $level2 ), "\n";
    }

If the caller wants to import level constants into a different namespace, it can be provided with the "use" command:

    use Log::Log4perl::Level qw(MyNameSpace);

After this $MyNameSpace::ERROR, $MyNameSpace::INFO etc. will be defined accordingly.

Numeric levels and Strings

Level variables like $DEBUG or $WARN have numeric values that are internal to Log4perl. Transform them to strings that can be used in a Log4perl configuration file, use the c<to_level()> function provided by Log::Log4perl::Level:

    use Log::Log4perl qw(:easy);
    use Log::Log4perl::Level;

        # prints "DEBUG"
    print Log::Log4perl::Level::to_level( $DEBUG ), "\n";

To perform the reverse transformation, which takes a string like ``DEBUG'' and converts it into a constant like $DEBUG, use the to_priority() function:

    use Log::Log4perl qw(:easy);
    use Log::Log4perl::Level;

    my $numval = Log::Log4perl::Level::to_priority( "DEBUG" );

after which $numval could be used where a numerical value is required:

    Log::Log4perl->easy_init( $numval );

LICENSE

This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself.

AUTHOR

Please contribute patches to the project on Github:

    http://github.com/mschilli/log4perl

Send bug reports or requests for enhancements to the authors via our

MAILING LIST (questions, bug reports, suggestions/patches): log4perl-devel@lists.sourceforge.net

Authors (please contact them via the list above, not directly): Mike Schilli <m@perlmeister.com>, Kevin Goess <cpan@goess.org>

Contributors (in alphabetical order): Ateeq Altaf, Cory Bennett, Jens Berthold, Jeremy Bopp, Hutton Davidson, Chris R. Donnelly, Matisse Enzer, Hugh Esco, Anthony Foiani, James FitzGibbon, Carl Franks, Dennis Gregorovic, Andy Grundman, Paul Harrington, Alexander Hartmaier David Hull, Robert Jacobson, Jason Kohles, Jeff Macdonald, Markus Peter, Brett Rann, Peter Rabbitson, Erik Selberg, Aaron Straup Cope, Lars Thegler, David Viner, Mac Yang.