Log::Log4perl::Filter::Boolean.3pm

Langue: en

Autres versions - même langue

Version: 2010-02-24 (ubuntu - 24/10/10)

Section: 3 (Bibliothèques de fonctions)

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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, Log::Log4perl::Filter::LevelMatch, Log::Log4perl::Filter::LevelRange, Log::Log4perl::Filter::StringRange Copyright 2002-2009 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.