Craig Rasmussen wrote:

On Apr 28, 2008, at 2:20 PM, Aleksandar Donev wrote:

...

On Monday 28 April 2008 12:49, Lionel, Steve wrote:

...

My personal preference is for choice 4, the IGNORE attribute (the specific spelling can be debated... There seems to be strong sentiment with some against such a thing, which I don't fully understand. Steve, I will throw this one back at you. I asked earlier, but never got a response:

What happens if the dummy (with the IGNORE attribute) is declared as INTEGER(4), and things are performed inside that the standard defines only for 4-byte integers (e.g., some bit packing operation). Then, the routine is called with a REAL(8) array? What if the array is of a derived type of size 1 byte?

What specifically will Intel Fortran do? Compile and give results that make no sense? If so, the standard must have *specific* restrictions on what the actual is allowed to be, and what it means. Only illegal cases can be left without a meaning.

What does Cray do?

If the routine is written in C and has a void* argument, I understand how it works. But I do not understand how it works if "everything is written in Fortran".

I don't understand either. I assume I must declare a TKR for the dummy and then tell the compiler to ignore what I have just declared? What can I do in the Fortran procedure? I can't think of anything very useful. I can't define it can I. I think we still require LANG=C.

The TKR ignore directives (and, I assume a similar attribute) affect only argument checking. Essentially the effect is to suppress error messages. Once inside the subprogram, you treat the dummy argument with the type, kind, and rank it was declared with. The only thing you skip is argument conformance checking. Traditionally these directives have been used in two environments. One is in archaic Fortran subroutines, typically named COPY or MOVE, that just do block memory copies. These were often written with integer arguments, but called with integer, real, or complex arguments. If the element size did not match, the user adjusted the number of elements to be copied. Such routines have no place in modern codes, but they still exist in some dusty decks, and the directive is an easy way to "fix" the code with minimal source changes. The other use of the directives is in interfaces for routines that are written in C that have void * arguments. In other words, like MPI case, which, when you think about it, is just another variant of the COPY/MOVE operations.

Perhaps I could use IGNORE(R) if the dummy were declared as a rank 1 array. However, I believe I can get the same thing with a assumed size, rank 1 dummy. At least the compiler I tried allowed me to call with a rank 2 actual.

Right. And if ignore(tkr) were added to the standard, there would be some limitations. Dummies that were represented by dope vectors would not be reasonable, for example. Cheers, Bill

Craig

-- Bill Long [email protected] Fortran Technical Support & voice: 651-605-9024 Bioinformatics Software Development fax: 651-605-9142 Cray Inc., 1340 Mendota Heights Rd., Mendota Heights, MN, 55120