You can’t always trace ideas. This one, I can.

David Farrell of wrote about Patching Perl, handling the detail that Perl modules always return true, so it’s convention that the least you need for a Perl module is package PackageName ; 1, but you may not like that behavior. (It’s cool. Read it. Learn from it.)

The other is … unspeakable. Let us not speak of it.

But, given the only things you need for a package is package PackageName ; 1,but we normally add sub new ( $class ) { ... } for old-school OOP or use Exporter qw(import) ; our @EXPORT = qq{ ... } for a more standard way. We do this because the point of libraries is code encapsulation, or at least grouping. You want to deal with Foo? use Foo; my $foo = Foo->new() or maybe use Foo qw{foo} ; my $out = foo($in);.

But, given that we have this way of functions, what could we do with it? How could we abuse Perl functions in ways that might be useful to us, but would clearly disguise functionality from others?

First-pass, my thought was that you could add Logging.

package LogMe;

use strict;
use warnings;
use utf8;
use feature qw{ postderef say signatures state };
no warnings qw{ experimental::postderef experimental::signatures };

use Log::Log4perl;
use UUID::Tiny ':std';

my $uuid;

    $uuid = create_uuid_as_string( UUID_TIME, time );
    my $status = qq{LogMe Begin: $uuid };
    my $logger = Log::Log4perl::get_logger('jacoby.logme');
    $logger->info( 'INFO: ' . $status );

    my $status = qq{LogMe End: $uuid };
    my $logger = Log::Log4perl::get_logger('jacoby.logme');
    $logger->info( 'INFO: ' . $status );


What’s happening here? Perl has five code blocks: BEGIN, UNITCHECK, CHECK, INIT, and END. BEGIN runs as close to the beginning of execution as possible and is commonly used to ensure configuration is set to avoid race conditions. END happens once everything is done, assuming there is no abnormal end.

In this case, [Log::Log4perl]( logs each time the program starts and ends, and we include a UUID to ensure that we can match each start and end, so we have a sense of which times it doesn’t end properly.

I don’t use the easy settings for Log4Perl.

log4perl.logger.jacoby.logme            = INFO, Appender2
log4perl.appender.Appender2             = Log::Log4perl::Appender::File
log4perl.appender.Appender2.filename    = /home/jacoby/.logme.log
log4perl.appender.Appender2.layout      = PatternLayout

This gives us this style of logging.

2018/07/24 11:21:05-INFO-oz-INFO: LogMe Begin: 2ec9bc90-8f55-11e8-82c4-bb26c0b07d34
2018/07/24 11:21:05-INFO-oz-INFO: LogMe End: 2ec9bc90-8f55-11e8-82c4-bb26c0b07d34

The question from here is why do this? Well…

  • Do people use this? You would have to add fun with AUTOLOAD, meaning you might call use LogMe qw{module_name} and have that function name become part of $status. If, after a while of logging, you realize that this is rarely called, you could refactor or retire the code, or if it’s called constantly, you could start looking at XS or other ways to improve it.
  • Bolt-On Debugging Everything involved here is in one library assignment, so you get this without changing anything in the original code.

Otherwise, I can’t see it. I clearly wrote this as an exercise, to scratch a curious itch, to expand my Perl powers and to add another article to my blog.

So, I ask my readers: Where would you use this? And what benefit do you see in disguising functionality and hiding it from your users?

If you have any questions or comments, I would be glad to hear it. Ask me on Twitter or make an issue on my blog repo.