Filter::Boolean(3) User Contributed Perl Documentation Filter::Boolean(3)
NAME
Log::Log4perl::Filter::Boolean - Special filter to combine the results
of others
SYNOPSIS
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(3), Log::Log4perl::Filter::LevelMatch(3),
Log::Log4perl::Filter::LevelRange(3), Log::Log4perl::Filter::MDC(3),
Log::Log4perl::Filter::StringRange(3)
LICENSE
Copyright 2002-2026 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.
perl v5.34.3 2026-08-15 Filter::Boolean(3)
log-log4perl 1.580.0 - Generated Tue Aug 25 18:52:31 CDT 2026