Rhys,
Hmmm...Looks like combination of a bug and a feature ;-)
According to the RM entry for H5Oset_comment, an attribute cannot have a
comment because it is not "an HDF5 object" - attribute doesn't have a header;
it is stored in the object header for a dataset, group, or named datatype.
But I would expect the second H5Oset_comment call to fail and leave a root
group comment intact. This looks like a bug to me. Will add it to our issues
database.
Thank you!
Elena
On Jan 14, 2011, at 4:43 PM, Rhys Ulerich wrote:
> Hi all,
>
> My understanding is that it is not valid to write a comment to an
> attribute. However, the following code runs without error on
> 1.8.5-p1:
>
> #include <hdf5.h>
>
> int main()
> {
> const hid_t f = H5Fcreate(
> "foo.h5", H5F_ACC_TRUNC, H5P_DEFAULT, H5P_DEFAULT);
> H5Oset_comment(f, "file comment");
>
> hsize_t dims = 1;
> const hid_t s = H5Screate_simple(1, &dims, NULL);
> const hid_t a = H5Acreate2(
> f, "x", H5T_NATIVE_INT, s, H5P_DEFAULT, H5P_DEFAULT);
> H5Sclose(s);
> int x = 5;
> H5Awrite(a, H5T_NATIVE_INT, &x);
> H5Oset_comment(a, "attribute comment");
> H5Aclose(a);
> H5Fclose(f);
>
> return 0;
> }
>
> Running the compiled binary and examining the foo.h5 file it produces
> with h5dump shows
>
> HDF5 "foo.h5" {
> GROUP "/" {
> COMMENT "attribute comment"
> ATTRIBUTE "x" {
> DATATYPE H5T_STD_I32LE
> DATASPACE SIMPLE { ( 1 ) / ( 1 ) }
> DATA {
> (0): 5
> }
> }
> }
> }
>
> where it appears that setting the comment on an attribute overwrites
> the file-level comment.
>
> Two questions arise:
>
> 1) Am I incorrect in saying that an attribute cannot contain a comment?
> 2) Is HDF5 1.8.5-p1 failing to detect a usage error in my sample code?
>
> Thanks,
> Rhys
>
> _______________________________________________
> Hdf-forum is for HDF software users discussion.
> [email protected]
> http://mail.hdfgroup.org/mailman/listinfo/hdf-forum_hdfgroup.org
_______________________________________________
Hdf-forum is for HDF software users discussion.
[email protected]
http://mail.hdfgroup.org/mailman/listinfo/hdf-forum_hdfgroup.org
