Vecs hold a reference to their DM. If the Vec is also composed to the DM, then you have a reference counting loop. Discovering and breaking general reference counting loops is hard; the named vectors are a restrictive feature so that it is not hard. I don't have a problem with other solutions, but that was the rationale. You can see the original commit. commit dfe153156869f5931ee6b299eecdcfd8470c0dd0 Author: Jed Brown <[email protected]> Date: Sun Mar 25 20:17:10 2012 -0500 Strip out bad idea of holding vec_sol in SNESDM, implement DMGetNamedGlobalVector() and implement restriction with it Hg-commit: 0040de20b98becd00af00473b94f3d32a4299b3d include/petsc-private/dmimpl.h | 10 ++++ include/petsc-private/snesimpl.h | 6 --- include/petscdm.h | 2 + src/dm/impls/da/dalocal.c | 94 +++++++++++++++++++++++++++++++++++ src/dm/interface/dm.c | 10 ++++ src/snes/interface/snes.c | 40 +++++++++++++-- src/snes/utils/dmsnes.c | 74 +-------------------------- 7 files changed, 154 insertions(+), 82 deletions(-) "Smith, Barry F." <[email protected]> writes:
Why have
PETSC_EXTERN PetscErrorCode DMHasNamedGlobalVector(DM,const char*,PetscBool*); PETSC_EXTERN PetscErrorCode DMGetNamedGlobalVector(DM,const char*,Vec*); PETSC_EXTERN PetscErrorCode DMRestoreNamedGlobalVector(DM,const char*,Vec*); PETSC_EXTERN PetscErrorCode DMHasNamedLocalVector(DM,const char*,PetscBool*); PETSC_EXTERN PetscErrorCode DMGetNamedLocalVector(DM,const char*,Vec*); PETSC_EXTERN PetscErrorCode DMRestoreNamedLocalVector(DM,const char*,Vec*);
when one can simply using the already existing PetscObjectCompose() and PetscObjectQuery() to attach named vectors to a given DM (or any other object in fact)?
Barry