The London Perl and Raku Workshop takes place on 26th Oct 2024. If your company depends on Perl, please consider sponsoring and/or attending.


rig - import groups of favorite/related modules with a single expression


version 0.04


In your /home/user/.perlrig yaml file:

         - strict
         - warnings
         - List::Util:
            - first
            - max
         - Data::Dumper

Back in your code:

   use rig favorite;

   # same as:
   #   use strict;
   #   use warnings;
   #   use List::Util qw/first max/;
   #   use Data::Dumper;

   # now have a ball:

   print first { $_ > 10 } @ary; # from List::Utils;
   print Dumper $foo;  # from Data::Dumper


This module allows you to organize and bundle your favorite modules, thus reducing the recurring task of useing them in your programs, and implicitly requesting imports by default.

You can rig your bundles in 2 places:

  • A file called .perlrig in your home or current working directory.

  • Packages undeneath the rig::task::<rig_task_name>, for better portability.


This module uses lots of internal gotos to trick modules to think they're being loaded by the original caller, and not by rig itself. It also hooks into import to keep modules loading after a goto.

Modules that don't have an import() method are instead evalled into the caller's package.

This is somewhat hacky, there are probably better ways of achieving the same results. We're open to suggestions on how to make loading modules more generic and effective. Just fork me on Github!



    use rig -file   => '/tmp/.rig';           # explicitly use a file
    use rig -engine => 'base';                # chooses the current engine
    use rig -path   => qw(. /home/me /opt);   # not implemented yet

    use rig moose, strictness, modernity;

    use rig 'kensho';            # loads a rig called kensho
    use rig ':kensho';           # skips files, goes straight to rig::task::kensho
    use rig 'kensho::strictive'; # skips files, uses rig::task::kensho::strictive
    use rig 'signes';

.perlrig YAML structure

         - <module> [min_version]
         - +<module> 
         - <module>:
            - <export1>
            - <export2>
            - ...
      also: <task2> [, <task3> ... ]

use section

  • Lists modules to be used.

  • Checks module versions (optional).

  • Lists exports (optional).

By default, modules in your rig are imported by calling import.

Alternatively, a plus sign + can be used in front of the module to force it to be loaded using the eval method, as such:

    eval "package <your_package>; use <module>;"

This may be useful to workaround issues with using import when none is available and rig fails to detect a missing import method, or things are just not working as expected.

also section

Used to bundle tasks into each other.


         - strict 
         - warnings
         - feature:
            - say
            - switch
         - Moose 1.0
         - Moose::Autobox
         - autodie
         - Method::Signatures
         - Try::Tiny
         - strict
         - warnings
         - Data::Dumper
         - Data::Alias
         - autodie
      also: modernity
         - List::Util:
            - first
            - max
            - min
         - Scalar::Util:
            - refaddr
         - Carp:
            - cluck
            - croak

The .perlrig file

The .perlrig file is where you keep your favorite rigs.

As mentioned earlier, rig looks for a .perlrig file in two directories by default:

   * The current working directory.
   * Your home directory.

Important: only one rig file is loaded per perl interpreter instance. This will probably change in the future, as .perlrig file merging should be implemented.


It could have had room to put your funky startup code, but it doesn't. This module is about order and parseability.

Having a structured file written in plain yaml makes it easier for worldly parsers to parse the file and understand your configuration.

Global Configuration

Use the $ENV{PERLRIG_FILE} variable to tell rig where to find your file.

   $ export PERLRIG_FILE=/etc/myrig
   $ perl

rig::task:: modules

A more distribution-friendly way of wiring up module bundles for your application is to ship them as part of the rig::task:: namespace.

   package rig::task::myfav;

   sub rig {
        return {
         use => [
            { 'warnings'=> [ 'FATAL','all' ] }
         also => 'somethingelse',

This is the recommended way to ship a rig with your distribution. It makes your distribution portable, no .perlrig file is required.

Out-of-the-box rig tasks

This module comes with 2 internal rigs defined:

Writing your own parser

Although this distribution only comes with a yaml parser for the .perlrig file. you can still write your own parser if you like:

   package rig::parser::xml;
   use base 'rig::parser::base';

   sub parse { return .... } 

   # meanwhile in Gotham City:

   package main;
   use rig -parser => 'xml';
   use rig 'fav-in-xml';


Although short, the api and yaml specs are still unstable and are subject to change. Mild thought has been put into it as to support modifications without major deprecations.

Startup Cost

There's an upfront load time (on the first use rig it finds) while rig looks for, parses and processes your .perlrig file. Subsequent calls won't look for any more files, as its structure will remain loaded in memory.

Ordered Load

As of right now, module loading order tends to get messed up easily. This will probably be fixed, as the author's intention is to load modules following the order set by the user in the .perlrig and use rig statements.


The authors feel that rig is a short name that is good for one-liners. It's lowercase because we feel it's a pragma-like module that augments the functionality of use. But rig is a unique enough name as to avoid clashing with future Perl pragmas.

We're sorry if it hurts anyone's lowercase sensibility.


  • Create a class to hold the perlrig definition.

  • Use Config::Any or similar for more agnostic and advanced file loading.

  • Straighten out and optimize internals.

  • Test many more modules for edge cases.

  • More verbs besides use and also, such as require, etc.

  • A cookbook of some sort, with everyday examples.

  • More tests.

  • Fix load sequence.


Toolkit - uses filters and AUTOLOAD to accomplish its import magic.

ToolSet - employs use base and package ...; eval ....