On Thu, Jul 19, 2012 at 1:19 PM, Barry Smith <bsmith at mcs.anl.gov> wrote:
> Why not implement it using PetscObjectQuery()/PetscObjectCompose()? and > not have to introduce a whole new datatype DMNamedVecLink linked list and > other crap? > The only reason this thing has to exist, and it really has to exist in some form, is that we have a reference loop. For example, the SNES Vec X is obtained from the DM (thus X references the DM), but must be made available to the KSP callback that uses the DM. If we attached X to the DM, then we would have a loop X -> DM -> X. Same for the TS vector needed in SNESComputeFunction. The general form of PetscObjectCompose allowing reference loops is terribly dangerous and imprecise (you end up implementing a sort of limited garbage collector that periodically looks for loops, but that is super dangerous in parallel because you need determinism in destruction). -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.mcs.anl.gov/pipermail/petsc-dev/attachments/20120719/a44c8a24/attachment.html>
