yum, and 2 packages that provide the same thing

Jeff Spaleta jspaleta at gmail.com
Fri Apr 18 00:23:16 UTC 2008


On Thu, Apr 17, 2008 at 4:00 PM, Stephen Warren
<s-t-rhbugzilla at wwwdotorg.org> wrote:
>  * The "first" package by some sorting order that matches


there is a sorting order when picking between different packages that
provide the same thing to fill a provides dep.. typically it is
expressed as "shortest" name wins.  The most common case is virtual
provides from packages with significantly different names.

Now the unison case.. is extremely special, in that you are fooled
into thinking that the two unison packages are suppose to compare in
the same versioning space. They are not. The packagenaming being used
for unison is a hack and you should not intuit that the numbers in the
package name suggest a version comparison.  Stop thinking about them
as a lower version and a higher version of the same codebase.  Think
of them as codebase forks.

The unison developers..in their infinite wisdom have decided that they
don't actually want to worry about backwards compatibility between
client versions, so if you need to talk across the network to
different machines you need to be sure you have the same version of
unison available on both machines or the magic doesn't work.

The horrible horrible package naming for unison that we have is a
result of that upstream decision to make sure people who want to use
unison can be sure they have the right versions of unison installed to
communicate to machines running other operating systems. The package
naming in the case of unison is done deliberately  to break how
version comparison in the package system is suppose to work.    It's a
corner case... that needs to die. Adding more logic at the packaging
layer to support what is really upstream's inability to provide
adequate protocol versioning support is wasted effort.


-jef




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