[Radiance-dev] Re: Radiance in Debian

[Bernd Zeimetz]

Hi Jack,

> I was just poking around a bit and I wonder about using
> /etc/alternatives to manage the conflict between the two versions of
> xform? So perhaps there could be /usr/bin/rgenbox for radiance and
> /usr/bin/ggenbox for gromacs which then get resolved by
> /etc/alternatives/genbox? This /etc/alternatives is new to me so I am
> not clear if I am thinking about this the right way.

The idea is good, and indeed alternatives are way to handle such
conflicts, BUT this is only allowed in the case that both programs
provide the same features. For example /usr/bin/x-www-browser is managed
by alternatives and is used as default web browser in the system, you
can use update-alternatives to select konqueror/iceweasel/....... to
provide it.
Same thing for diversions using dpkg-divert - it's only allowed if both
programs are able to replace each other. For example did gpsdrive ship
it's own version of gpsd for some time, and while installing the
original gpsd a diversion was added so /usr/bin/gpsd was provided from
the gpsd package.
genbox from Gromacs and genbox from Radiance have completely different
functions, so using diversions or alternatives on them is forbidden by
policy.

Imagine you'd accidentally have the genbox from gromacs instead of the
Radiance genbox because you've messed with the alternatives, and it
would provide some output which looks sane to the rest of Radiance -
you'd end up with something completely different then expected.
That's not a huge problem here, but imagine such a confusion would
happen with some destructive tool. That's why Debian's policy says:
Binaries MUST have a unique name, and alternatives/diversions are only
allowed if the programs are exchangeable without any problems for the user.


Hope that explains it :)

Bernd

-- 
Bernd Zeimetz
<bernd at bzed.de>                         <http://bzed.de/>