Hi, I would like to extend Debian Policy on libraries depending on services (daemons) that they can speak to.
Let me bring to examples, one made up,, one for which I filed a bug recently. But as far as I can tell this question comes up from time to time: 1. libpulse0 & friends ---------------------- libpulse0 is a client library for the Pulseaudio server. It doesn't do much without pulseaudio. Q: Should libpulse0 have Depends: pulseaudio? There a similar libraries like libjack0 to talk to Jackd. Q: Should libjack0 have Depends: jackd1? The answer should probably be the same for both questions. If the answer is "yes", this would result in an application that can output audio via Pulseaudio or Jackd and linking the respective liubraries pulling in *both* Pulseaudio and Jackd (and possibly other sound servers as well). 2. python3-secretstorage ------------------------ python3-secretstorage is a library to talk to a Dbus Secret Store API implemented by several programs (gnome-keyring, libkf5wallet-bin, keepassxc). Q: Should python3-secretstorage Depends: default-dbus-session-bus | dbus-session-bus? Q: Should python3-secretstorage Depends: gnome-keyring | ...? If the answer is "yes", this would result in an application that can manage credentials via Secret Store to pull in DBus, systemd-sysv, gnome-keyring, and lots of other stuff, even when one just wants to, for example, install (public) packages from PyPI (#1058945). (There is a practical different between Python and C in that Python makes it easier to handle optional linkage: just try `import foobar` and handle the import error; proper plugin handling in C is significantly more work.) 3. The general case ------------------- Many Debian packages build with a large set of optional features enabled, thus linking many libraries. I believe that if all libraries implementing support to talk to some service would mandate installing said service, then this would result in many installations getting many more packages, especially when also considering use of software in containers. Some service might even conflict with each other, e.g., one would probably only want to use a single sound server. I therefore think that libraries (be it classic C shared object libraries or Python modules or others) should in general *not* have Depends: or Recommends: relations on services (DBus services, DBus itself, daemons, ...). A quick poll on IRC in #-devel seemed to show a majority of people who responded agreeing with this. (This does not have to apply to libnss-* or libpam-* which are not actually libraries, but plugins.) Ansgar
