Fortran 77 Interface

[Ray Osborn]

I would support Freddie's suggestion of providing both methods.  The only 
other drawback of using the EQUIVALENCE method that occurred to me was that
the user can't put the value directly in the function call e.g.

      status = NXputdata (fileid,'NeXus data')

would not work.  If we informed users that they could either use NXputdata,
with equivalenced integer*1 arrays, or NXputchardata, with character data,
then we can leave it to the user which they prefer.

I'm against using CFORTRAN since it adds a whole new layer of complexity to
Fortran code installation.  It seems to me that Freddie has already solved
most of the portability issues with his Fortran 77 interface and CFORTRAN
will only add more headaches.

Can we take a vote on either of the two options :

1) Provide both NXputdata and NXputchardata explaining how the user can use
either for character data.

2) Provide only NXputdata, and ask the user to equivalence character strings
to a INTEGER*1 or BYTE array.

Ray
--
Dr Ray Osborn                Tel: +1 (630) 252-9011
Materials Science Division   Fax: +1 (630) 252-7777
Argonne National Laboratory  E-mail: ROsborn at anl.gov
Argonne, IL 60439-4845




> We could provide both ways of doing things e.g. a user can call
> "nxputattr" and "nxputdata" with character types after doing an
> equivalence, or they can call "nxputcharattr" and "nxputchardata" etc. if
> they would rather not. If they use f90, they do not need to be concerned
> with this as the "function overloading" will match up the correct
> function call for them.
>
> Freddie
>
> On Fri, 17 Sep 1999, Ray Osborn wrote:
>
>> Freddie had made the suggestion that we should require the user to
>> equivalence any character string to an integer*1 (or BYTE) array, which
>> he/she then uses as the NXputdata/NXgetdata argument etc. I've just checked
>> that this works fine on our Alpha/VMS system, even without making any
>> arrangements to null-terminate the passed array.  I don't think that this is
>> because VMS Fortran initializes all arrays as 0 since I used the same buffer
>> more than once, the second time with a shorter string.  The second time, the
>> buffer would have been padded with spaces.
>>
>> My tentative conclusion is that Freddie is right that null termination is
>> not required here because we only pass the array to and from HDF with a
>> defined length.  In other words, we don't even have to modify
>> NXputdata/NXgetdata to cope with NX_CHAR datatypes.  This would satisfy
>> Mark's preference to have the same interface for C and F77 interfaces.
>>
>> It does require that the user use EQUIVALENCE statements but this is fairly
>> easy to explain.
>>
>> Any more opinions?
>>
>> Ray
>> --
>> Dr Ray Osborn                Tel: +1 (630) 252-9011
>> Materials Science Division   Fax: +1 (630) 252-7777
>> Argonne National Laboratory  E-mail: ROsborn at anl.gov
>> Argonne, IL 60439-4845
>>
>>