[arch-dev-public] Fwd: Re: Fwd: Perl packaging guidelines.

Aaron Griffin aaronmgriffin at gmail.com
Tue Feb 9 13:26:14 EST 2010

On Tue, Feb 9, 2010 at 3:32 AM, Firmicus <Firmicus at gmx.net> wrote:
> [Forwarding this from Xyne]
>>  This is an area where I have a pretty solid experience, as as perl dev,
>>  arch user, and maintainer of several perl packages in extra and
>>  community. I tend to agree with Allan here. We should only package and
>>  take into consideration what on CPAN is called a distribution, i.e. a
>>  tarball containing a bunch or related perl modules. The mapping between
>>  modules and distributions is available in a plain text database on each
>>  CPAN mirror, and can be figured out by the common tools used to install
>>  cpan stuff from the command-line (cpan and cpanp). I think it is quite a
>>  BAD idea to put all module names in the provides array, as this can
>>  easily yield hundreds of elements without obvious advantage I can think
>>  of. Our poor lil Pacman has better things to do than take that overload
>>  into account.
> Is the overhead even significant? How expensive are PROVIDES lookups?
> (Coincidentally, I've thought for a while now that there should be a
> single PROVIDES list for the local database to avoid opening hundreds
> of files unnecessarily, even if that is quite fast).
> What about when distributions change their module roster? This has
> happened before and will happen again. I see robust dependency
> resolution as an "obvious advantage". If any important modules ever get
> moved around (e.g. subsumed into the base distribution from a popular
> module), then all packages which depend on that module would need to
> update their depends array.
> The fact that META.yml files for distributions on CPAN specify modules
> and not distributions shows that the dependencies are actually the
> modules themselves. Ignoring upstream convention and Pacman's built-in
> capabilities to shave a little bit of time off of a PROVIDES lookup
> doesn't right to me, especially when you factor in the potential
> dependency breakage, however unlikely that is to affect large
> distributions.
>>  That said, I do acknowledge Xyne's effort! I have written a very similar
>>  tool years ago, which is still available in AUR (perl-cpanplus-pacman),
>>  but for which I have alas not dedicated as much effort and commitment as
>>  Xyne did with pacpan. My own approach has however inspired another
>>  project, called perl-cpanplus-dist-arch (also in AUR), which IMHO is
>>  superior to both my own cpan4pacman and Xyne's pacpan. (That said I
>>  still use cpan4pacman (together with a few helper shell scripts and the
>>  devtools) to maintain my own local repository of 550 CPAN packages, all
>>  of which I keep uptodate with relative ease).
> I've looked at perl-cpanplus-dist-arch while rewriting the pacpan
> backend. I found the entire CPANPLUS backend to be overkill for
> creating Pacman packages. Pacpan uses the same files and gets the same
> results, but without the CPAN shell and other bells and whistles that
> have no significance for Pacman packaging.
> That said, if there are particular features that
> perl-cpanplus-dist-arch has that pacman lacks, let me know which and I
> will consider adding them. If that project does show itself to be
> superior for Pacman packaging then I probably switch the backend over
> to it, but so far the current backend works as expected and is fairly
> simple with no external dependencies.
> Two follow-up questions:
> Do you at least support the idea of renaming CPAN packages with
> non-standard names to their standard names?
> If not, what about including the standard name in the provides array?
> If pacpan didn't include the individual modules in the arrays but
> instead mapped then all to their distribution, how would you see the
> matter then?

I have to say that I'm not really up to speed on the perl module
stuff, but I can see the benefit of adding the actual CPAN name into
the provides array. I have wasted time in the past looking for some
"Random::FooBar" type module, only to find that it's in perl-libfoobar
or something silly

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