Filter::Boolean(3)

📦
version 1.57 · 9 versions
, in opensuse-leap 16.0

✨ NAME ✨

okay so bestie, this is the manual page for Filter::Boolean(3) from User Contributed Perl Documentation, and the module itself is Log::Log4perl::Filter::Boolean — a special filter that combines the results of other filters. It’s giving “why use one filter when you can make them team up” energy 👑.

🌸 SYNOPSIS 🌸

Like, here’s the config vibe:

log4perl.logger = WARN, AppWarn, AppError

log4perl.filter.Match1       = sub { /let this through/ }
log4perl.filter.Match2       = sub { /and that, too/ }
log4perl.filter.MyBoolean       = Log::Log4perl::Filter::Boolean
log4perl.filter.MyBoolean.logic = Match1 || Match2

log4perl.appender.Screen        = Log::Dispatch::Screen
log4perl.appender.Screen.Filter = MyBoolean
log4perl.appender.Screen.layout = Log::Log4perl::Layout::SimpleLayout

🦋 DESCRIPTION 🦋

Sometimes, it’s useful to combine the output of various filters to arrive at a log/no log decision. While Log4j, Log4perl’s mother ship, chose to implement this feature as a filter chain, similar to Linux' IP chains, Log4perl tries a different approach.

Typically, filter results will not need to be passed along in chains but combined in a programmatic manner using boolean logic. "Log if this filter says 'yes' and that filter says 'no'" is a fairly common requirement but hard to implement as a chain.

Log::Log4perl::Filter::Boolean is a special predefined custom filter for Log4perl which combines the results of other custom filters in arbitrary ways, using boolean expressions:

log4perl.logger = WARN, AppWarn, AppError

log4perl.filter.Match1       = sub { /let this through/ }
log4perl.filter.Match2       = sub { /and that, too/ }
log4perl.filter.MyBoolean       = Log::Log4perl::Filter::Boolean
log4perl.filter.MyBoolean.logic = Match1 || Match2

log4perl.appender.Screen        = Log::Dispatch::Screen
log4perl.appender.Screen.Filter = MyBoolean
log4perl.appender.Screen.layout = Log::Log4perl::Layout::SimpleLayout

Log::Log4perl::Filter::Boolean’s boolean expressions allow for combining different appenders by name using AND (&& or &), OR (|| or |) and NOT (!) as logical expressions. Parentheses are used for grouping. Precedence follows standard Perl. Here’s a bunch of examples:

Match1 && !Match2            # Match1 and not Match2
!(Match1 || Match2)          # Neither Match1 nor Match2
(Match1 && Match2) || Match3 # Both Match1 and Match2 or Match3

🎀 SEE ALSO 🎀

  • Log::Log4perl::Filter
  • Log::Log4perl::Filter::LevelMatch
  • Log::Log4perl::Filter::LevelRange
  • Log::Log4perl::Filter::MDC
  • Log::Log4perl::Filter::StringRange

💖 LICENSE 💖

Copyright 2002-2013 by Mike Schilli <m@perlmeister.com> and Kevin Goess <cpan@goess.org>.

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

👑 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.

Bye bestie — this was Filter::Boolean(3), source/version perl v5.42.0, dated 2022-10-22. Stay iconic 💖✨

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