Log::Log4perl - changing an appenders threshold

arc444 has asked for the wisdom of the Perl Monks concerning the following question:

Hi. Im trying to change the thresold on an appender, but without success. Why do I want to do this ? - it would be in response to a '-debug' option provided to the script ( not shown for clarity ) Minimal case example of the issue is shown below. Suggestions very gladly welcomed Thank you.

#!/usr/bin/perl

use strict;
use warnings;

use Log::Log4perl;

my $log4p_conf = q(

    log4perl.rootLogger=DEBUG, SCREEN

    log4perl.appender.SCREEN=Log::Log4perl::Appender::Screen
    log4perl.appender.SCREEN.layout=SimpleLayout
    log4perl.appender.SCREEN.Threshold=INFO

);

Log::Log4perl->init(\$log4p_conf);

my $log = Log::Log4perl->get_logger("");

# This appears to have no effect :
Log::Log4perl->appender_by_name('SCREEN')->threshold('DEBUG');

$log->fatal("fatal msg");
$log->error("error msg");
$log->warn("warn msg");
$log->info("info msg");
$log->debug("debug msg");
$log->trace("trace msg");
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Re: Log::Log4perl - changing an appenders threshold by Anonymous Monk on Sep 07, 2017 at 11:51 UTC
Try calling method on $log	[reply]
Re^2: Log::Log4perl - changing an appenders threshold by arc444 (Novice) on Sep 12, 2017 at 16:29 UTC
Thanks for the suggestion, but there are no methods available on the $log object that will modify the appenders, only methods to adjust the logger itself. I have however now found a solution, to set the SCREEN appender to threshold of 'debug' : $Log::Log4perl::Logger::APPENDER_BY_NAME{'LOGFILE'}->threshold('DEBUG') This does work as I required. I believe that the method : Log::Log4perl->appender_by_name('SCREEN')->threshold('DEBUG') amends the 'actual appender' - however because these appenders are 'wrapped' it needs to be the 'wrapper class' itself that needs adjusted, to give me the desired result. I had achieved this initially by modifying the objects data directly using : ${$Log::Log4perl::Logger::APPENDER_BY_NAME{'SCREEN'}}{'level'} = 20000 This is what initially seemed to be suggested at : http://log4perl.sourceforge.net/releases/Log-Log4perl/docs/html/Log/Log4perl.html#356d5 : "The previously mentioned method appender_by_name() returns a referrence to the real appender object. If you want access to the wrapper class (e.g. if you want to modify the appender's threshold), use the hash $Log::Log4perl::Logger::APPENDER_BY_NAME{...} instead, which holds references all appender wrapper objects." After re-reading a few times, Im now aware of the threshold method on the actual 'wrapper class' ( $Log::Log4perl::Logger::APPENDER_BY_NAME{'LOGFILE'} ) and can therefore also use the 'friendly name' ( ie DEBUG/TRACE/WARN ) rather than a numeric ( 30000/20000/5000 ) Hope someone also finds this useful !	[reply]