++ed by:

3 PAUSE users
10 non-PAUSE users.

Nicolas Steenlant
and 2 contributors


This guide has been written to help anyone interested in contributing to the development of Catmandu.

Please read this guide before contributing to Catmandu or related projects, to avoid wasted effort and maximizing the chances of your contributions being used.


There are many ways to contribute to the project. Catmandu is a young yet active project and any kind of help is very much appreciated!


You don't have to start by hacking the code, spreading the word is very valuable as well!

If you have a blog, just feel free to speak about Catmandu.

Of course, it doesn't have to be limited to blogs or Twitter. Feel free to spread the word in whatever way you consider fit and drop us a line on the Catmandu user mailing list noted below.

Also, if you're using and enjoying Catmandu, rating us on cpanratings.perl.org, explaining what you like about Catmandu is another very valuable contribution that helps other new users find us!

Mailing list

Subscribing to the mailing list and providing assistance to new users is incredibly valuable.


We value documentation very much, but it's difficult to keep it up-to-date. If you find a typo or an error in the documentation please do let us know - ideally by submitting a patch (pull request) with your fix or suggestion (see "Patch Submission").


You can write extensions (plugins) for Catmandu extending core functionality or contribute to Catmandu's core code, see "Patch Submission" below.


This section lists high-level recommendations for developing Catmandu, for more detailed guidelines, see "Coding Guidelines" below.

Quality Assurance

Catmandu should be able to install for all Perl versions since 5.10.1, on any platform for which Perl exists. We focus mainly on GNU/Linux (any distribution).

You should avoid regressions as much as possible and keep backwards compatibility in mind when refactoring. Stable releases should not break functionality and new releases should provide an upgrade path and upgrade tips such as warning the user about deprecated functionality.

Quality Supervision

We can measure our quality using the CPAN testers platform: http://www.cpantesters.org.

A good way to help the project is to find a failing build log on the CPAN testers: http://www.cpantesters.org/distro/D/Catmandu.html

If you find a failing test report, feel free to report it as a GitHub issue: http://github.com/LibreCat/Catmandu/issues.

Reporting Bugs

We prefer to have all our bug reports on GitHub, in the issues section: http://github.com/LibreCat/Catmandu/issues.

Please make sure the bug you're reporting does not yet exist.


Set up a development environment

If you want to submit a patch for Catmandu, you need git and very likely also Module::Build. We also recommend perlbrew (see below) to test and develop Catmandu on a recent version of perl. We also suggest App::cpanminus) to quickly and comfortably install perl modules under perlbrew.

In the following sections we provide tips for the installation of some of these tools together with Catmandu. Please also see the documentation that comes with these tools for more info.

Perlbrew tips (Optional)

Install perlbrew for example with

    cpanm App::perlbrew

Check which perls are available

    perlbrew available

At the time of writing it looks like this


Then go on and install a version inside Perlbrew. I recommend you give a name to the installation (--as option), as well as compiling without the tests (--n option) to speed it up.

  perlbrew install -n perl-5.16.3 --as catmandu_dev -j 3

Wait a while, and it should be done. Switch to your new Perl with:

  perlbrew switch catmandu_dev

Now you are using the fresh Perl, you can check it with:

  which perl

Install cpanm on your brewed version of perl.

  perlbrew install-cpanm

Install dependencies (required)

Install Module::Build

    $ cpanm Module::Build

Get Catmandu sources

Get the Catmandu sources from github (for a more complete git workflow see below):

Clone your fork to have a local copy using the following command:

    $ git clone git@github.com:LibreCat/Catmandu.git

The installation is then straight forward:

    $ cd Catmandu
    $ perl Build.PL
    $ ./Build
    $ ./Build test
    $ ./Build install

Patch Submission (Github workflow)

The Catmandu development team uses GitHub to collaborate. We greatly appreciate contributions submitted via GitHub, as it makes tracking these contributions and applying them much, much easier. This gives your contribution a much better chance of being integrated into Catmandu quickly!

To help us achieve high-quality, stable releases, git-flow workflow is used to handle pull-requests, that means contributors must work on their dev branch rather than on their master. (Master should be touched only by the core dev team when preparing a release to CPAN; all ongoing development happens in branches which are merged to the dev branch.)

Here is the workflow for submitting a patch:

  • Fork the repository http://github.com/LibreCat/Catmandu (click "Fork")

  • Clone your fork to have a local copy using the following command:

        $ git clone git://github.com/$myname/Catmandu.git
  • As a contributor, you should always work on the dev branch of your clone (master is used only for building releases).

        $ git remote add upstream https://github.com/LibreCat/Catmandu.git
        $ git fetch upstream
        $ git checkout -b dev upstream/dev

    This will create a local branch in your clone named dev and that will track the official dev branch. That way, if you have more or less commits than the upstream repo, you'll be immediately notified by git.

  • You want to isolate all your commits in a topic branch, this will make the reviewing much easier for the core team and will allow you to continue working on your clone without worrying about different commits mixing together.

    To do that, first create a local branch to build your pull request:

        # you should be in dev branch here
        git checkout -b pr/$name

    Now you have created a local branch named pr/$name where $name is the name you want (it should describe the purpose of the pull request you're preparing).

    In that branch, do all the commits you need (the more the better) and when done, push the branch to your fork:

        # ... commits ...
        git push origin pr/$name

    You are now ready to send a pull request.

  • Send a pull request via the GitHub interface. Make sure your pull request is based on the pr/$name branch you've just pushed, so that it incorporates the appropriate commits only.

    It's also a good idea to summarize your work in a report sent to the users mailing list (see below), in order to make sure the team is aware of it.

  • When the core team reviews your pull request, it will either accept (and then merge into dev) or refuse your request.

    If it's refused, try to understand the reasons explained by the team for the denial. Most of the time, communicating with the core team is enough to understand what the mistake was. Above all, please don't be offended.

    If your pull-request is merged into dev, then all you have to do is to remove your local and remote pr/$name branch:

        git checkout dev
        git branch -D pr/$name
        git push origin :pr/$name

    And then, of course, you need to sync your local dev branch with the upstream:

        git pull upstream dev
        git push origin dev

    You're now ready to start working on a new pull request!



The official website is here: http://librecat.org/

Mailing Lists

A mailing list is available here: librecat-dev@mail.librecat.org


The official repository is hosted on GitHub at the following location: http://github.com:LibreCat/Catmandu

Official developers have write access to this repository, contributors are invited to fork it if they want to submit patches, as explained in the Patch submission section.


This guide is heavily based on Dancer2::Development.