[Rpm-ecosystem] Rich deps syntax finalization

Florian Festi ffesti at redhat.com
Wed Aug 26 12:00:42 UTC 2015

On 08/26/2015 10:47 AM, Florian Festi wrote:
> Right now libsolv does not distinguish between different orders of the
> operands. But we have already discussed making the OR operator
> preferring the left most operand. This is something RPM does not really
> care about but of cause has implications for packaging if implemented in
> libsolv.

May be I should append to this slightly:

AFAIK libsolv uses the Suggests: and Enhances: to pick one of *equally
adequate* packages. But we stil need to gain more experience on how well
this works.

But my feeling is that people are too much concerned with preference for
packages. I understand that it is a topic in Fedora with the change of
depsolvers and all the hidden assumptions breaking. But... outside of
installing fixed groups during installation package preferences are
pretty weak. They stand against a raging sea of other dependencies and
present, past and future user commands -  waiting to be washed away.

So if one of multiple providers should be chosen the right way is to add
an hard Requires to the package, meta package or comps group that cares.

Rich dependencies are at first not a tool to express package preferences
or to allow more flexibility (although they might be used for this).
They are primarily a tool to get Requires right in more complicated
cases that cannot be solved with the Requires we already have.



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