#log.conf:
log4perl.rootLogger=ERROR, LOGFILE

log4perl.appender.LOGFILE=Log::Log4perl::Appender::File
log4perl.appender.LOGFILE.filename=/var/log/myerrs.log

log4perl.appender.LOGFILE.mode=append
    
log4perl.appender.LOGFILE.layout=PatternLayout
log4perl.appender.LOGFILE.layout.ConversionPattern=[%r] %F %L %c - %m%n

# in your perl-script:
use Log::Log4perl;
Log::Log4perl->init("log.conf");

# Anywhere you log:
package blah;
use  Log::Log4perl;

sub new() {
   ...
   $self->{debug} = $debug;
   ...
}

sub method {
    my $self=shift;
    my($param) = @_;

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

    $log->debug("Debug ...") if $self->{debug};
    $log->info("Info ...") if $ $self->{debug};
    $log->error("Error ...") if $self->{debug};