dependencies done right

dave has a point regarding cpan module dependencies: it can be troublesome to install everything correctly. however, we can get the best of both worlds... if we create packages from cpan modules for linux distributions. indeed, we can then use all the tools that the distributions have worked on and polished since so long a time. not counting the fact that's definitely the goal of a linux distribution to simplify things, and integrate software ready to be used.

to do so, we're standing once again on the shoulders of giants: cpanplus comes with various backends. of course, the most used is the one that really installs the modules. but with cpanplus::dist, it's easy to create modules for your distribution: debian, mandriva or fedora backends exist. and thus, creating a package for your distribution is as easy as (for mandriva in this case):

$ cpan2dist --format CPANPLUS::Dist::Mdv Foo::Bar
$ sudo rpm -Uvh ~/rpm/RPMS/noarch/perl-Foo-Bar.rpm

of course, this is only half of the story. after all, we don't want the users to do this - we're indeed trying to save them the hassle of building the modules.

so, we need to create the rpms (or debs) and provide them in the distribution. which is a bit more difficult, since we need to create the packages for the wanted module, and all the prereqs. and for each of them, we need to import them in the distribution build system. all that can take quite some time.

which is why i'm currently working on app::cpan2pkg (readers of this blog have already heard about that), which does everything automatically - well, that's the goal, at least. if you're a contributor, just run:

$ cpan2pkg Foo::Bar

it will build automatically the packages for Foo::Bar and all its dependencies, import them in the distribution repository, and send them (in order) on the distribution build system, where they will be made available for users later on...

and the end result is achieved, as an end user:

$ sudo urpmi perl-Foo-Bar

that will install Foo::Bar along with all its dependencies. no build fuss, no dependency done wrong, no need to have this gcc or that lib installed. everything will be fetched & installed for you...

so, we still retain the testing culture because packagers continue the regular build with all the test suite. users have their modules ready to be installed as easy as ever. and maybe we'll stop hearing about people complaining about long dependency chains. because dave is right: who gives a shit about that?

note to self: now just go back to work on it so i can release v1.0.0!