Hi! We are currently working on adding weak and rich dependencies to upstream RPM. There are basically two parts: #1 Adding weak dependencies as already used by SuSE and others: Recommends:, Suggests:, Supplements: and Enhances:. We agreed with Michael Schröder to not use SuSE's current implementation but to add new tags for a cleaner interface and an easy update path for already existing packages. This is planned to be part of the next RPM version. As old tools will just ignore the new tags this isn't a big compatibility issue. Support in rpmbuild can probably back ported easily. #2 Allow Boolean expressions of (Name Flag Version) terms in Requires:, Conflicts: and the new weak dependencies (rich dependencies). This will add a new expressive strength to RPM's dependency model and allow fixing a couple of packaging problems we don't have a solution for right now and also get rid of some special case solutions like hand coded language pack support. As we are still figuring out some of the implementation details and implications this feature may or may not make it in the next release. Packages using such Boolean expressions will not work with old versions of rpm and other related tools and it is still unclear to what extend this feature can be back ported. What implication does this have on your distribution? Although this new features do affect rpm and packages directly and you may want to reflect that in your packaging policy the main impact is outside of rpm itself. The weak dependencies are basically ignored by rpm and need to be handled in your dependency solver, installer, updater, software management tool - however you call it. If you are already using weak dependencies you want to make sure to add support for the new tags before updating to the next major rpm version. Also expect that most of your patches adding the old support will fail to apply. In general I expect the transition to be comparably easy. We will probably even add some compatibility code in upstream RPM to make your life easier. Talk to us. Getting the support into createrepo and libsolv is taken care of. This should cover Fedora and OpenSUSE and may be others. If you use a different dependency solver you have various options: You may just ignore the new features for now. The weak dependencies can just be ignored. But you won't be able to process packages with Boolean expression in Requires: or Conflicts:. If your solver is not NP complete you may want to consider changing to a libsolv based solution or any other NP complete solver that has a chance of growing support for weak and rich dependencies in the future. If you already have a NP complete solver - may be already with support for weak dependencies - and want to stick with it you should consider adding support for rich dependencies. Right now there is no code to look at and there are still some implementation details that we need to figure out. We will keep you updated on the rpm-maint list. I wrote a document describing more technical details. Find it attached to this mail. Florian
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