[CentOS] Re: are RPMForge and EPEL compatible?

[Axel Thimm]

On Sun, Dec 09, 2007 at 01:15:08PM -0600, Les Mikesell wrote:
> Axel Thimm wrote:
>> On Fri, Dec 07, 2007 at 05:12:06PM -0600, Les Mikesell wrote:
>>> But it would be even better if we could live with the assumption that 
>>> repos will have incompatibilities, whether accidental or intentional. 
>>> Then it would become a choice of which to install and things wouldn't 
>>> break when somewhere else updates first.  Then you could focus on making 
>>> your versions better instead of compatible - and the politics wouldn't 
>>> matter.
>>
>> Sorry, that's not possible. Just to give an example: For some reason
>> you favour repo A and make it trump over repo B. Both repos ship
>> libfoo and repo B ships also appbaz needing libfoo with a couple more
>> configure options turned on.
>>
>> No smart package manager in the world will detect this breakage. One
>> could strat thinking about stricter dependencies etc. but there will
>> always be real-world scenarios like the above spoiling your master
>> plan.
>
> How much more information would rpm/yum need to store and consider in order 
> to understand that they should never overwrite a package from one 
> repository with one from a different repository without explicit 
> instructions?

Les, please read the example again. It assumes that rpm/yum already
does so (and indeed with some plugins you can do that), but shows that
you still end up with a broken system.

> Permitting explicit repository-specific dependencies would be 
> nice too, although that could be worked around given the ability to control 
> the initial repo for a package and an understanding that no other repo's 
> version should replace it without permission even if it has the same name 
> and a higher version number.

I'll just repeat myself: If the packagers don't cooperate no technical
solution will be able to really cover compatibilty problems. You'll
paper over some of them and create a false feeling that you have
mastered the compatibility problem and still wonder later why it
doesn't work. I've seen dozen of such false bug reports which I call
"partial/selective enabling of repos". Google the last term and you
find many bad examples of such "solutions".
-- 
Axel.Thimm at ATrpms.net
-------------- next part --------------
A non-text attachment was scrubbed...
Name: not available
Type: application/pgp-signature
Size: 189 bytes
Desc: not available
URL: <http://lists.centos.org/pipermail/centos/attachments/20071209/bdefd8e5/attachment.sig>