Tricky question about libxfconf, xfconfd and soname

[Yves-Alexis Perez]

Ok, I have a tricky question, which will affect the way xfconf is
packaged in debian.

Currently, we have:

libxfconf-0-0 with:
- /usr/lib/libxfconf-0.so.0.1.0
- /usr/lib/libxfconf-0.so.0 -> libxfconf-0.so.0.1.0
libxfconf-0-dev with:
- headers, doc etc.
- /usr/lib/libxfconf-0.a
- /usr/lib/libxfconf-0.so -> libxfconf-0.so.0.1.0
libxfconf-0-dbg with debugging symbols
xfconf with xfconf daemon.

libxfconf-0-dev, libxfconf-0-dbg and xfconf depends on libxfconf-0-0
with the same *binary* version (meaning 4.5.91-1 at the moment).

The xfconf separate package is known to be problematic, because
currently one can install an xfconf-enabled app (which will bring
libxfconf-0-0) and not have the xfconf package installed, and thus no
daemon. This is not good. We have an xfconf dependency in xfce4 package
but it's not enough. So I thought about merging back xfconfd into
libxfconf-0-0 package, so it's installed as soon as an app needs xfconf.

This is what GNOME people do with gconf.

But then I have a problem with upgrades

If/when xfconf soname changes, the lib name becomes libxfconf-0.so.1 and
we have to rename the packages to match this, so it becomes libxfconf-0-1. 

This is because binary compatibility is changed, and thus old apps won't
work on the new lib (and new apps won't work on the old lib), so we have
to manually change the Build-Depends: ont the packages. This means we
can have two libxfconf installed at the same time, with their own set of
apps:

libxfconf-0-0 with old apps
libxfconf-0-1 with new apps

Then, I have a problem with the xconf daemon, which is currently
installed in /usr/bin/xfconfd, and is thus present in both packages
meaning they can't be installed at the same time.

GNOME puts the daemon in a versioned directory in /usr/lib to fix that:
/usr/lib/libgconf2-4/gconfd-2

So there's no overwrite problem if the soname change.

But they have a stable soname for gconf since ages, and thus they didn't
have problems with multiple installations: what if I have two xfconf
daemon installed. Which one should be started? (the recent one yeah, but
that needs to be chosen correctly). Anyway I don't think the current
setup will accept to run xfconfd from /usr/lib, but maybe it'd be
doable.

Another solution would be to keep the seperate xfconf package and force
the automatic dependency. Currently when something is built against
libxfconf, dpkg automagically adds a dependency on libxfconf-0-0 (>= correct
version). I could tune that to add a dependency on libxfconf-0-0 (>=
correct version), xfconf (>= correct version).

I'm not sure it's a good idea wrt. debian library packaging guidelines,
so I'll have to chek this before, but it's an idea.

Anyway, what is your thoughts about this? I know Xfce apps could be
upgraded all at once, and thus it should be possible to have only one
xfconf at a time. But that's ok for Xfce apps. for goodies or other
application wanting an xfconf backend, it could break. So how should be
handled those setups?

Cheers, (and sorry for that long mail. if there's any huge misake in
there, please forgive and correct me :) )
-- 
Yves-Alexis