alternatives: multiple versions for the same package

[Riccardo Mottola]

Hi,

Progressing, I have now to preparecthe "backend" for the GNUstep
packages.

The backend provides the graphical part and can be configured with
different libraries,s upporting different dependencies.

The best rendering is currently supported with the "cairo" library, but
one can also use the older "xlib" backend which has thus much less
dependencies and is useful e.g. on a server where just a couple of small
programs are run without much graphics.

Does mgar support his? How?
Essentially, I would build "gnustep-back-xlib" and "gnustep-back-cairo"
and they should be installed mutually exclusive.
All other applications need to depend on either one or the other, the
choice is free, but one is needed.

On systems like debian, one builds two packages and puts them mutually
on dependency.

On other systems like gentoo linux, I would build only one package
"gnustep-back" and then be able to pass an option, a flavour or
something like that to the time being.

Riccardo