[NeXus-tech] flush in hdf4

[Mark Koennecke]

Paul,

Paul Kienzle wrote:
> Hi,
>
> After many hours I managed to build and test the new napi on OS X for  
> HDF4/5/xml.
>
> The storage size is now used by the python bindings when putting  
> character data rather than the length of the stored data.  In the  
> process of fixing this I cleaned up a dangling pointer reference.   
> Between these, I hope the python wrapper is now stable, and #162 can  
> be closed.
>
> A separate issue I fixed in the python bindings was to force a close  
> data for each open data. Otherwise, the path we are maintaining on  
> the python side gets confused.
>
> An unresolved issue is that HDF4 but not HDF5 or XML closes the  
> currently open data group on NXflush.  I noticed this because I was  
> interleaving flush class with putslab calls.  This wasn't caught  
> before because the opendata call was in the loop with putslab.  This  
> behaviour isn't documented.
>
>   
It is even worth. With HDF4 the file is closed and reopened. This is
also why NXflush takes a pointer to the handle and not only the
handle as an argument. There is a reason for this behaviour: At the
time it was implemented and I think even now, the HDF-4 API did
not provide for a proper flush. Thus to  get flush functionality with HDF-4
the only option is to close and reopen the file.

                Mark
> I was unable to build and test under windows+mingw, and didn't try  
> linux.  Can someone please run "python nxstest hdf4 hdf5 xml" on  
> these two platforms?
>
> Thanks,
>
>    - Paul
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