Which script initialized module?

Question

In Perl, is there any way to tell which .pl script has initialized this instance of a module?

Specifically, I'd like to get the name of the script calling a module, which has a Log4perl object it. That way, I'll know which .log file I want to write to within the module.

Am I doing this wrong? If I define the $logger in my .pl script, will any $logger calls within the module write to the same .log file as the calling script?

I don't have any sample code yet, but have been reading up on Log4perl. Basically, if I set an Appender to a file, caller.log, which is the file appender for my calling script, caller.pl, I'd want any logging defined in the custom imported module, to also write to caller.log (implicitly, if possible -- obviously I could just pass the name of the log name when I initialize the module instance).

Is this possible without passing arguments specifying which File Appender the module should write to? Doesn't Log4perl use just one $logger instance?

Also, let me know if I'm way out, and if there's a different approach I should be considering.

Thank you

EDIT: Sorry, after I posted this, I looked at the Related Links, and I guess my search wording just wasn't correct. It looks like this is a pretty good solution: Self logging Perl modules (without Moose)

If anyone has any other ideas, though, please let me know.

EDIT 2: Finally tested, and got it to work as I had wanted -- was a lot easier than was making it out to be, too!

This is my setup, pretty much:

Module.pm

package Module;

use Log::Log4perl qw(get_logger :levels);
use Data::Dumper;

my $logger = get_logger("Module");

sub new {
    my ($class, $name) = @_;

    my @caller = caller(0);
    $logger->debug("Creating new Module. Called by " . Dumper(\@caller));

    my $object = { 'name' => $name };

    return bless($object, $class);  
}

caller.pl

use Module;
use Log::Log4perl qw(get_logger :levels);
use Data::Dumper;

my $PATH = "$ENV{'APPS'}/$ENV{'OUTDIR'}";
my $SCRIPT = "caller";

my $logger = get_logger("Module");
$logger->level($DEBUG);

my $file_appender = Log::Log4perl::Appender->new("Log::Dispatch::File", 
                        filename=> "$PATH/$SCRIPT.log", 
                        mode => "append",);
$logger->add_appender($file_appender);

my $layout = Log::Log4perl::Layout::PatternLayout->new("%d %p> %F{1}:%L %M - %m%n");
$file_appender->layout($layout);

my $lib = Module->new('Chris');

$logger->info(Dumper($lib));

Answer 1

You could subclass Log4perl, overriding its constructor. In your custom constructor, use caller() to get the filename that called the constructor and put it in $self.

Answer 2

You can put a subroutine hook into @INC that can run arbitrary code, as documented in perldoc -f require. For example:

# UseLogger.pm
package UseLogger;
sub import { unshift @INC, \&UseLogger::log_use }
sub log_use {
    my ($self, $filename) = @_;
    my @c = caller(0);
    print "Module $filename required in file $c[1] line $c[2]\n";
    return 0;
}
1;

$ perl -MUseLogger my_script.pl
Module feature.pm required in file my_script.pl line 2
Module Encode.pm required in file my_script.pl line 5
Module XSLoader.pm from /usr/lib/perl5/5.14.0/cygwin-thread-multi-64int/Encode.pm line 13
...

Answer 3

$0 contains the path to the script. You can use File::Basename's basename if you want to want the file name component.