[petsc-dev] need for HDF5 < 1.8.0 support?

[Hapla Vaclav]

> On 7 Dec 2018, at 10:35, Hapla Vaclav <vaclav.hapla at erdw.ethz.ch> wrote:
> 
> I wanted to add support for HDF5 attributes of groups (currently only datasets).
> 
> But I already feel like held back by supporting HDF5 older than 1.8.0. Do we still need that?
> 
> My arguments to get rid of that support:
> 1) It seems we already use some 1.8.0+ functions anyway (might be my fault, though).
> 2) We could get rid of all those #if
> 3) There were quite some useful API functions introduced in that release which would make the code simpler. For instance, H5O* functions allow handling groups and datasets the same way.
> 
> Ad 2,3 consider this
> 
> /* OLD */
> #if (H5_VERS_MAJOR * 10000 + H5_VERS_MINOR * 100 + H5_VERS_RELEASE >= 10800)
>  if (dataset) {
>    PetscStackCallHDF5Return(object, H5Dopen2, (h5, parent, H5P_DEFAULT));
>  } else if (type == H5O_TYPE_GROUP) {

Sorry this should be just else everywhere :-)

>    PetscStackCallHDF5Return(object, H5Gopen2, (h5, parent, H5P_DEFAULT));
>  }
> #else
>  if (dataset) {
>    PetscStackCallHDF5Return(object, H5Dopen, (h5, parent));
>  } else if (type == H5O_TYPE_GROUP) {
>    PetscStackCallHDF5Return(object, H5Gopen, (h5, parent));
>  }
> #endif
> ...
>  if (dataset) {
>    PetscStackCallHDF5Return(err, H5Dclose, (object));
>  } else if (type == H5O_TYPE_GROUP) {
>    PetscStackCallHDF5Return(err, H5Gclose, (object));
>  }
> 
> 
> /* NEW */
>  PetscStackCallHDF5Return(object, H5Oopen, (h5, parent, H5P_DEFAULT));
>  ...
>  PetscStackCallHDF5Return(err, H5Oclose, (object));
> 
> 
> Additionally, function H5Oget_info() which can say whether the object is group or dataset was also introduced only in 1.8.0. So the dataset flag above would have to be set by a user it seems...
> 
> So I personally think it's already about time to leave the old HDF5 API behind... Objections? If no, I would make a PR which would clean the code from the #ifs and forbid the older versions already in configure.
> 
> Vaclav