package Log::Log4perl::Resurrector; use warnings; use strict; use File::Temp qw(tempfile); use constant INTERNAL_DEBUG => 0; ########################################### sub import { ########################################### resurrector_init(); } ################################################## sub resurrector_fh { ################################################## my($file) = @_; local($/) = undef; open FILE, "<$file" or die "Cannot open $file"; my $text = <FILE>; close FILE; print "Read ", length($text), " bytes from $file\n" if INTERNAL_DEBUG; my($tmp_fh, $tmpfile) = tempfile( UNLINK => 1 ); print "Opened tmpfile $tmpfile\n" if INTERNAL_DEBUG; $text =~ s/^\s*###l4p//mg; print "Text=[$text]\n" if INTERNAL_DEBUG; print $tmp_fh $text; seek $tmp_fh, 0, 0; return $tmp_fh; } ########################################### sub resurrector_loader { ########################################### my ($code, $module) = @_; # Skip Log4perl appenders if($module =~ m#^Log/Log4perl/Appender#) { print "Ignoreing $module (Log4perl-internal)\n" if INTERNAL_DEBUG; return undef; } # Skip unknown files if(!-f $module) { # We might have a 'use lib' statement that modified the # INC path, search again. my $path = pm_search($module); if(! defined $path) { print "File $module not found\n" if INTERNAL_DEBUG; return undef; } print "File $module found in $path\n" if INTERNAL_DEBUG; $module = $path; } print "Resurrecting module $module\n" if INTERNAL_DEBUG; my $fh = resurrector_fh($module); $INC{$module} = 1; return $fh; } ########################################### sub pm_search { ########################################### my($pmfile) = @_; for(@INC) { # Skip subrefs next if ref($_); my $path = File::Spec->catfile($_, $pmfile); return $path if -f $path; } return undef; } ########################################### sub resurrector_init { ########################################### unshift @INC, \&resurrector_loader; } 1; __END__ =head1 NAME Log::Log4perl::Resurrector - Dark Magic to resurrect hidden L4p statements =head1 DESCRIPTION Loading C<use Log::Log4perl::Resurrector> causes subsequently loaded modules to have their hidden ###l4p DEBUG(...) ###l4p INFO(...) ... statements uncommented and therefore 'resurrected', i.e. activated. This allows for a module C<Foobar.pm> to be written with Log4perl statements commented out and running at full speed in normal mode. When loaded via use Foobar; all hidden Log4perl statements will be ignored. However, if a script loads the module C<Foobar> I<after> loading C<Log::Log4perl::Resurrector>, as in use Log::Log4perl::Resurrector; use Foobar; then C<Log::Log4perl::Resurrector> will have put a source filter in place that will extract all hidden Log4perl statements in C<Foobar> before C<Foobar> actually gets loaded. Therefore, C<Foobar> will then behave as if the ###l4p DEBUG(...) ###l4p INFO(...) ... statements were actually written like DEBUG(...) INFO(...) ... and the module C<Foobar> will indeed be Log4perl-enabled. Whether any activated Log4perl statement will actually trigger log messages, is up to the Log4perl configuration, of course. There's a startup cost to using C<Log::Log4perl::Resurrector> (all subsequently loaded modules are examined) but once the compilation phase has finished, the perl program will run at full speed. Some of the techniques used in this module have been stolen from the C<Acme::Incorporated> CPAN module, written by I<chromatic>. Long live CPAN! =head1 AUTHORS Mike Schilli <m@perlmeister.com> =head1 COPYRIGHT AND LICENSE Copyright 2002-2007 by Mike Schilli E<lt>m@perlmeister.comE<gt> This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself. =cut