El mar, 03-03-2009 a las 11:25 -0800, Zac Medico escribió: > > You're right. It's easy to says it in words but if you tried to > actually implementing you'd find that the PROPERTIES=virtual concept > simplifies the problem a lot and makes it possible to optimally > solve some cases of bug 141118 that couldn't otherwise be solved > optimally without the information that PROPERTIES=virtual provides. > > What we're talking about is a cost calculation and in order for the > cost calculation to be as accurate as possible, we need to know > which ebuilds have zero-cost to install (the virtual ones do not > install anything directly so they are considered to have zero-cost > in themselves). If you consider all ebuilds to have equal cost then > your calculation won't be as accurate as it could be. Knowing which > ebuilds are virtual gives a hint to the resolver that it should > perform a "lookahead" in the cost calculation. > > We could implement a similar lookahead mechanism for non-virtual > ebuilds, but it's more useful for the virtual ones. Backtracking > (which isn't implemented yet but is planned for bug 1343) would also > be useful for implementing additional cost optimizations (like the > one for bug 260225). > - -- > Thanks, > Zac
No problem. Thanks for the explanation :-)
