lib::projectroot - easier loading of a project's local libs


version 1.010


  # your_project/bin/somewhere/deep/down/
  use strict;
  use warnings;
  # look up from the file's location until we find a directory
  # containing a directory named 'lib'. Add this dir to @INC
  use lib::projectroot qw(lib);

  # look up until we find a dir that contains both 'lib' and 'foo',
  # add both to @INC
  use lib::projectroot qw(lib foo);

  # look up until we find 'lib' and 'local'. Add 'lib' to @INC,
  # load 'local' via local::lib
  use lib::projectroot qw(lib local::lib=local);

  # based on the dir we found earlier, go up one dir and try to add
  # 'Your-OtherModule/lib' and 'Dark-PAN/lib' to @INC
  lib::projectroot->load_extra(Your-OtherModule Dark-PAN);

  # the same as above
  use lib::projectroot qw(lib local::lib=local extra=Your-OtherModule,Dark-PAN);

  # if you want to know where the project-root is:
  say $lib::projectroot::ROOT;  # /home/domm/jobs/Some-Project

  # also load local::libs installed in extras
  use lib::projectroot qw(lib local::lib=local extra_with_local=Your-OtherModule,Dark-PAN);


I'm usually using a setup like this:

  ├── AProject
  │   ├── bin
  │   │   ├── db
  │   │   │   └──
  │   │   ├── onetime
  │   │   │   ├── fixup
  │   │   │   │   └──
  │   │   │   └──
  │   │   └── web.psgi
  │   ├── lib
  │   └── local
  ├── MyHelperStuff
  │   └── lib
  └── CoolLib-NotYetOnCPAN
      └── lib

There is AProject, which is the actual code I'm working on. There is also probably BProject, e.g. another microservice for the same customer. AProject has its own code in lib and its CPAN dependencies in local (managed via Carton and used via local::lib). There are a bunch of scripts / "binaries" in bin, in a lot of different directories of varying depth.

I have some generic helper code I use in several projects in MyHelperStuff/lib. It will never go to CPAN. I have some other code in CoolLib-NotYetOnCPAN/lib (but it might end up on CPAN if I ever get to clean it up...)

lib::projectroot makes it easy to add all these paths to @INC so I can use the code.

In each script, I just have to say:

  use lib::projectroot qw(lib local::lib=local);

lib is added to the beginning of @INC, and local is loaded via local::lib, without me having to know how deep in bin the current script is located.

I can also add

  lib::projectroot->load_extra(qw(MyHelperStuff CoolLib-NotYetOnCPAN));

to get my other code pushed to @INC. (Though currently I put this line, and some other setup code like initialising Log::Any into AProject::Run, and just use AProject::Run;)

You can also define extra dists directly while loading lib::projectroot:

  use lib::projectroot qw(

If your extra dists themselves have deps which are installed into their local::lib, you can add those via extra_with_local:

  use lib::projectroot qw(

You can access $lib::projectroot::ROOT if you need to know where the projectroot actually is located (e.g. to load some assets)


Some ideas for future releases:

  • what happens if $PERL5LIB is already set?

  • think about the security issues raised by Abraxxa ( 2014-12-02 18:42:07)


  • FindBin - find out where the current binary/script is located, but no @INC manipulation. In the Perl core since forever. Also used by lib::projectroot.

  • Find::Lib - combines FindBin and lib, but does not search for the actual location of lib, so you'll need to know where your scripts is located relative to lib.

  • FindBin::libs - finds the next lib directory and uses it, but no local::lib support. But lots of other features

  • File::FindLib - find and use a file or dir based on the script location. Again no local::lib support.

  • and probably more...


Thanks to eserte, Smylers & abraxxa for providing feedback at Meta-thanks to kentaro for running prepan, a very handy service!

Thanks to koki, farhad and Jozef for providing face-to-face feedback.


Thomas Klausner <>


This software is copyright (c) 2014 - 2021 by Thomas Klausner.

This is free software; you can redistribute it and/or modify it under the same terms as the Perl 5 programming language system itself.