[petsc-dev] inconsistency for its own sake?

[Jed Brown]

Sounds good.


On Fri, Jan 11, 2013 at 1:18 PM, Barry Smith <bsmith at mcs.anl.gov> wrote:

>
> On Jan 11, 2013, at 1:02 PM, Jed Brown <jedbrown at mcs.anl.gov> wrote:
>
> > On Fri, Jan 11, 2013 at 12:58 PM, Barry Smith <bsmith at mcs.anl.gov>
> wrote:
> >
> >
> >
> > So this works by convention that we name the argument to match the man
> page (e.g., SNESFunction) in all interfaces?
>
>    Yes
>
> > The compiler won't help to enforce that consistency,
>
>    Not yet, but maybe a couple tweaks to LLVM will get us there :-)
>
> > but it'll deal with the documentation duplication.
>
>    Yes (and missing in some functions like SNESGetFunction() and not
> existing like in other places).
>
>   Barry
>
> >
> >
> > Is this a good middle-ground? Something wrong with it?
> >
> >   Barry
> >
> > > Cons of typedef:
> > > * typedef is less transparent when reading code
> > > * information is more scattered (harder for people that don't have the
> source code indexed and don't know where to find definitions)
> > > * because every usage does not need to be updated, it's hard to
> determine consequences of a change when reading diff
> > >
> > > I'll stop using function pointer typedefs if you don't like them.
> > >
> > > On Fri, Jan 11, 2013 at 10:26 AM, Barry Smith <bsmith at mcs.anl.gov>
> wrote:
> > >
> > >    The thing I don't like about typedef's for function pointers is
> that they do not display the calling sequencing in the code
> > >
> > >   For example  from
> > >
> > > > typedef struct _n_TSDM *TSDM;
> > > > struct _n_TSDM {
> > > >   TSRHSFunction rhsfunction;
> > >
> > >   or
> > >
> > >    PetscErrorCode TSSetRHSFunction(TS ts, TSRHSFunction rhsfunction)
> > >
> > >   I have no freaking idea what the calling sequence of rhsfunction is.
> but with
> > >
> > > > typedef struct _n_TSDM *TSDM;
> > > > struct _n_TSDM {
> > > >   PetscErrorCode (*TSRHSFunction)(TS,PetscReal,Vec,Vec,void*);
> > >
> > >  or
> > >
> > >     PetscErrorCode TSSetRHSFunction(TS ts, PetscErrorCode
> (*TSRHSFunction)(TS,PetscReal,Vec,Vec,void*);
> > >
> > > boom I know exactly the calling sequence.
> > >
> > >    Maybe there is some way we can do manual pages for these beasties
> and consistency of names in different locations so we get the best of both
> worlds?
> > >
> > >    Barry
> > >
> > >
> > >
> > > On Nov 25, 2012, at 3:58 AM, Jed Brown <jedbrown at mcs.anl.gov> wrote:
> > >
> > > > On Sun, Nov 25, 2012 at 4:42 AM, Barry Smith <bsmith at mcs.anl.gov>
> wrote:
> > > >
> > > > typedef struct _n_KSPDM *KSPDM;
> > > > struct _n_KSPDM {
> > > >   PetscErrorCode
> (*computeoperators)(KSP,Mat,Mat,MatStructure*,void*);
> > > >   PetscErrorCode (*computerhs)(KSP,Vec,void*);
> > > >   PetscErrorCode (*computeinitialguess)(KSP,Vec,void*);
> > > >
> > > > typedef struct _n_SNESDM *SNESDM;
> > > > struct _n_SNESDM {
> > > >   PetscErrorCode (*computefunction)(SNES,Vec,Vec,void*);
> > > >   PetscErrorCode (*computegs)(SNES,Vec,Vec,void*);
> > > >   PetscErrorCode
> (*computejacobian)(SNES,Vec,Mat*,Mat*,MatStructure*,void*);
> > > >
> > > >   /* objective */
> > > >   PetscErrorCode (*computeobjective)(SNES,Vec,PetscReal*,void*);
> > > >
> > > >
> > > > typedef struct _n_TSDM *TSDM;
> > > > struct _n_TSDM {
> > > >   TSRHSFunction rhsfunction;
> > > >   TSRHSJacobian rhsjacobian;
> > > >
> > > >   TSIFunction ifunction;
> > > >   TSIJacobian ijacobian;
> > > >
> > > > The PETSc style guide says  to avoid typedef of function pointers
> unless there is a damn good reason to use them (or it should);
> > > >
> > > > Can we revisit this choice in the interest of writing one man page
> that documents the assumptions that one can make about a callback routine?
> I hate duplicating the same information in TS{Set,Get}IFunction() and
> DMTS{Set,Get}IFunction(). Also, if a typedef is used everywhere, we can
> more reliably find all places that depend on it. (using grep or M-x
> gtags-find-symbol).
> > > >
> > > > but why use them for TS but not for SNES or KSP functions?
> > > >
> > > > Because they were already defined for use with
> TSSetIFunction()/TSGetIFunction().
> > >
> > >
> >
> >
>
>
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