See this example, after multiple casts, the code directly accesses VecScatter_MPI_General's members, with an assumption that from->n is the total number of receive processors. When I separate intranode / internode communications, I have to maintain this assumption.
385: *PetscErrorCode <http://www.mcs.anl.gov/petsc/petsc-current/docs/manualpages/Sys/PetscErrorCode.html#PetscErrorCode> MatMatMultNumeric_MPIDense(Mat <http://www.mcs.anl.gov/petsc/petsc-current/docs/manualpages/Mat/Mat.html#Mat> A,Mat <http://www.mcs.anl.gov/petsc/petsc-current/docs/manualpages/Mat/Mat.html#Mat> B,Mat <http://www.mcs.anl.gov/petsc/petsc-current/docs/manualpages/Mat/Mat.html#Mat> C)*386: { 389: Mat_MPIAIJ *aij = (Mat_MPIAIJ*) A->data; 393: VecScatter <http://www.mcs.anl.gov/petsc/petsc-current/docs/manualpages/Vec/VecScatter.html#VecScatter> ctx = aij->Mvctx;394: VecScatter_MPI_General *from = (VecScatter_MPI_General*) ctx->fromdata;395: VecScatter_MPI_General *to = (VecScatter_MPI_General*) ctx->todata; 411: PetscMalloc4 <http://www.mcs.anl.gov/petsc/petsc-current/docs/manualpages/Sys/PetscMalloc4.html#PetscMalloc4>(B->cmap->N*from->starts[from->n],&contents->rvalues,412: B->cmap->N*to->starts[to->n],&contents->svalues,413: from->n,&contents->rwaits,414: to->n,&contents->swaits); --Junchao Zhang On Fri, Aug 10, 2018 at 10:33 PM Matthew Knepley <knep...@gmail.com> wrote: > On Fri, Aug 10, 2018 at 11:29 PM Junchao Zhang <jczh...@mcs.anl.gov> > wrote: > >> It seems we do not have naming conventions for private members. >> > > I am not sure I understand. There are no public members. For private > functions, we do have > a naming convention, but it is newly created, so many of the existing > functions break the rules. > > Matt > > >> --Junchao Zhang >> >> >> On Fri, Aug 10, 2018 at 9:43 PM Matthew Knepley <knep...@gmail.com> >> wrote: >> >>> On Fri, Aug 10, 2018 at 5:43 PM Junchao Zhang <jczh...@mcs.anl.gov> >>> wrote: >>> >>>> I met several bugs that remind me to raise this question. In PETSc, >>>> object of type A can arbitrarily access object of type B's data. But >>>> designer of B may later change the meaning of its data (and of course, >>>> update B's interfaces, which are usually local to few files). The designer >>>> may think the job is done, but actually it is not. He/she has to grep the >>>> code to know where its data members are accessed (that is relatively easy >>>> to get) and what is the contract, for example, is an array assumed to be >>>> sorted (that is hard to know). With C++, one can use private to minimize >>>> data exposure. >>>> >>> >>> This just has to be coding discipline. People should not be accessing >>> private members. >>> >>> Matt >>> >>> >>>> --Junchao Zhang >>>> >>> >>> >>> -- >>> What most experimenters take for granted before they begin their >>> experiments is infinitely more interesting than any results to which their >>> experiments lead. >>> -- Norbert Wiener >>> >>> https://www.cse.buffalo.edu/~knepley/ <http://www.caam.rice.edu/~mk51/> >>> >> > > -- > What most experimenters take for granted before they begin their > experiments is infinitely more interesting than any results to which their > experiments lead. > -- Norbert Wiener > > https://www.cse.buffalo.edu/~knepley/ <http://www.caam.rice.edu/~mk51/> >
