Barry Smith <bsm...@petsc.dev> writes: >> On Feb 1, 2023, at 9:17 PM, Matthew Knepley <knep...@gmail.com> wrote: >> >> On Wed, Feb 1, 2023 at 9:06 PM Barry Smith <bsm...@petsc.dev >> <mailto:bsm...@petsc.dev>> wrote: >>> >>> Hmm, When I do >>> >>> def somePythonfunction(): >>> ... >>> x = da.createLocalVec() >>> .... >>> return >>> >>> The x seems to be properly "garbage collected" at some point; I was >>> guessing it was at the return or some time later than the return, but it >>> did not wait until PetscFinalize(). >>> >>> So does the x above HAVE to exist until PetscFinalize()? If not then >>> somehow Python realizes x is no longer referenced and VecDestroy() is >>> called on it when some garbage collection takes place. I would like the >>> same thing happen with the x = da.getLocalVec() but calling >>> x.da.restoreLocalVec() instead of x.destroy(). Note specifically >>> parallelism doesn't play a role here because x is local. >> >> It can happen at a random time, so it is unsafe to structure without a >> "with" since it could hold the local vector maybe after the user tries to >> destroy the DA. > > Thanks. I am assuming you are talking about the getLocalVec() case. So it > appears I need to dynamically attach an __exit__() method to the Vec in > da.getLocalVec() so that restoreLocalVec() gets called > https://www.geeksforgeeks.org/with-statement-in-python/ when the local vector > goes out of scope of the with. > > I assume I can have multiple independent objects created with a with or I > guess I could nest them when needed for local representations of u and du for > TS.IFunction.
Yes. See `with v.localForm() as loc` in src/binding/petsc4py/test/test_vec.py and the corresponding implementation. There are a few other similar context handlers. https://gitlab.com/petsc/petsc/-/commit/afbe0322dffa
