Ok, it looks like a lot of people are having trouble with the semantics of the rich deps operators. I'll try a short introduction:
Requires, Recommends, Suggests, Supplements, Enhances and Conflicts are all matched against the Provides. With the new rich deps Provides stay the way they are (NAME FLAGS VERSION) while all the other relations can use the new Boolean operators. Right now Requires: are matched against the Provides: and if no match is found an error is issued. With rich deps we do the same matching but instead of jumping to conclusions we create a Boolean value: TRUE if there is a match FALSE if there isn't. All rich deps operators are Boolean operators[1] working on these Boolean values. For Requires: (pkgA | pkgB) We search for matches for pkgA and pkgB and then combine the truth values with OR. If the result is FALSE we create an error as Requires need to be TRUE (Conflicts need to be FALSE). As this is all Boolean algebra the operators can be nested arbitrarily. E.g. Requires: (pkgA | (pkgB & pkgC)) The same way is the IF/? operator just a Boolean operator. The suggested IF and ? use different order of the operands but are other wise the same. They are equivalent to the following - may be more familiar operators (dots representing the operands). (. IF .) (. OR NOT .) (. <- .) aka Converse implication [2] (. ? .) (NOT . OR .) (. -> .) aka Material implication [3] If the very same way would the NOT operator inverse the Truth value of its operand: (NOT pkgA) is TRUE if there is no match. But NOT could also be used to negate larger expressions. As (NOT pkgA) equivalent to Conflicts: pkgA. Having the NOT operator would allow "using Conflicts" in more complicated Requires: statements. E.g. Requires: (pkgA | (pkgB AND NOT pkgC)) Which "means" pkgB can be used as an alternatve to pkgA if pkgC is not installed. But you can also just do the Boolean calculation for given set of matches. If you step back a bit things are still the same old same old. Rpm checks if Requires are fulfilled and there are no Conflicts by matching and calculating the Boolean values (and issues errors if needed). And Libsolv will actually figure out what packages need to be added (or removed) to make the Requires: TRUE and the Conflicts: FALSE (and handle all the weak deps). I hope this clears things up a little bit. Florian [1] https://en.wikipedia.org/wiki/Truth_function [2] https://en.wikipedia.org/wiki/Converse_implication [3] https://en.wikipedia.org/wiki/Material_conditional -- Red Hat GmbH, http://www.de.redhat.com/ Registered seat: Grasbrunn, Commercial register: Amtsgericht Muenchen, HRB 153243, Managing Directors: Charles Cachera, Michael Cunningham, Michael O'Neill, Charles Peters _______________________________________________ Rpm-ecosystem mailing list Rpm-ecosystem@lists.rpm.org http://lists.rpm.org/mailman/listinfo/rpm-ecosystem
