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Debhelper Plugin to Support Dist::Zilla Packages Natively

The Debian package dh-dist-zilla provides a debhelper sequence addon named 'dist_zilla'.

The intention is to be able to build Debian packages (.deb files) directly from a Dist::Zilla based Perl package without generating the CPAN package manually first. It is analogous to using autoreconf to generate the configure script.

The orig.tar.gz file must only contain the dist.ini and source files but not the generated files like META.yml, README, etc.

See dh-dist-zilla.pod for details on how to use it.

Background

The Perl community and CPAN in particular use a few tools to build Perl packages. The classic approach is to write a Makefile.PL script using ExtUtils::MakeMaker. The alternative variant uses Build.PL written with Module::Build. Both are part of the Perl core, but Module::Build has been deprecated recently and will be removed from the core with the next Perl release. For the distribution on CPAN a few more files like LICENSE, MANIFEST, META.yml, and README need to be added.

There is some tedium in writing all these files and there is no surprise to find code generators for them. Module::Starter is such a code generator that is very commonly used. It helps a lot getting started. However, maintenance still needs to make sure that information like version numbers or documentation is kept consistent.

Enter Dist::Zilla. The basic promise of Dist::Zilla, also known by its command line program dzil, is to keep all relevant information exactly once in a place where the particular piece of information fits best. Given the appropriate plugin dzil build will generate all the files needed for CPAN. E.g., the author, version, and license type is stored in exactly one place (typically in a file calleddist.iniand only there) and then used to add it in the appropriate places. Likewise MANIFEST and other boilerplate files are created or updated by each invocation of dzil build.

Technically, dzil can be used like module-starter or any other code generator. On the other hand its full potential is only taken advantage of if the generated files are never touched and only dist.ini and the other files proper to the package are editied. This makes development more consistent and eliminates whole classes of bugs.

With dzil you also avoid having to commit to either ExtUtils::MakeMaker or Module::Build. You can switch back and forth by replacing a Dist::Zilla plugin specification. If another successor to MakeMaker should appear and be successful you will most certainly be able to use a Dist::Zilla plugin to make use of it. This, of course, only applies if you are just using features supported by both or all build mechanisms you want to switch between them.

Debian Packaging of Perl Code

When packaging Perl code Debian relies heavily on CPAN or at least on the package contents of a package conforming to the CPAN standard. Debhelper can rely on either Makefile.PL or Build.PL to be present and conform to the common standard procedures accepting all their well defined options.

If the package is built and maintained using Dist::Zilla it would be advantageous to build from the original source files like dist.ini rather than base it on derived files like Build.PL. The most prominent benefits are avoiding inconsistencies and incorporating all improvements and bug fixes that went into Dist::Zilla.

Another concern is that generated files should not enter a VCS like Git. Not only are generated files redundant and can be recreated whenever needed, but they can easily become inconsistent and therefore be confusing and lead to subtle bugs.

The purpose of dh-dist-zilla is to enable debhelper to build a Debian package for Perl code directly from dist.ini and the original source code. In particular, it allows to build a Debian package directly from a VCS checkout.

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Version Numbers

We try to conform to Semantic Versioning with the only exception that we omit trailing zeros, i.e. version 1 is equivalent to version 1.0.0.

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