Am Mo., 22. Okt. 2018 um 17:32 Uhr schrieb Marvin Renich <m...@renich.org>:
>
> * Matthias Klumpp <matth...@tenstral.net> [181021 14:04]:
> > libgpgme is communicating with gnupg in the background - having
> > libgpgme without gnupg itself will render the library completely
> > unusable and break existing users of the library.
>
> This keeps getting repeated in this thread in spite of the fact that
> multiple people have stated that having libgpgme installed without gnupg
> is useful in a very reasonable scenario.
>
> > Also, gnupg/libgpgme are tiny, so you won't waste much disk space
> > here.
>
> See Steve Langasek's reply.
>
> Why are some maintainers so adamant about using Depends when Recommends
> is the correct dependency?
> [...]
Because having a real dependency eliminates another source of bugs.
The library will throw weird (for unexperienced end-users) errors and
they have to hunt down a solution for why something isn't working as
they expect. However, if a dependency relation exists, the package
maintainer can *ensure* that the shipped package is always in a usable
state, preventing end-users from wasting time in figuring out why
something does not work, while only adding the additional cost of
consuming a bit more disk space for people who don't use the feature.
I have seen this happening countless of times. Ensuring the user has a
working configuration and can't accidentally break it is pretty key.
Experienced users will always be able to track issues down in case
modules are missing, but the average user who just installed something
from a software center, will get frustrated and waste time in finding
a solution for their problem.
The "Recommends" relation should work here in theory, in practice
though people manage to remove stuff that was recommended by accident,
or even configure APT to never install recommends, and then end up
with things not working (granted, in the latter case it's their own
fault).
I've seen this when changing the dependency relation of some
PackageKit libraries on the packagekit daemon to a Recommends - that
initially resulted in lots of issues, as the PackageKit libraries
don't do much with their accompanying D-Bus activated daemon. As an
end result, the dependency relations were just shifted from the
library to the tools depending on the library, to ensure users have a
working configuration and don't break their GUI updater.
In this particular case I think a Recommends relation is justified,
because some server software also exists where the admin might not
want PK to be running, as it is first a D-Bus daemon and second an
admin tool to install software.
Due to that experience though I am pretty certain that if someone
removed a vital dependency from a shared library and the software that
uses it receives bug reports from users who can't use the adverties
feature, the maintainer of said software would not hesitate to add
that dependency to the software to ensure it functions properly for
users who need that feature (unless that dependency was very big).
The situation is entirely different though for software that is
designed to be extensible and handles the case of a missing module
gracefully. In that case, a soft dependency is better. In any case, I
think that is up to the maintainer to decide, as they know the
software best and can make sure that it works well for most of its
audience.
Cheers,
Matthias
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