(j3.2006) (SC22WG5.3585) OPTIONAL arguments and C interop
Wed Jul 16 14:25:57 EDT 2008
Van Snyder wrote:
> On Wed, 2008-07-16 at 09:47 -0500, Bill Long wrote:
>> A side effect of this design is that OPTIONAL and VALUE cannot be both
>> specified for a particular dummy argument.
Sorry, I should have said that the above restriction would apply only
for interfaces with BIND(C).
> I don't understand this problem.
> I would think that processors could use their Fortran conventions for
> argument forms that don't exist in C, i.e., assumed-shape arrays,
The TR is adding these as interoperable.
> optional arguments,
> and optional+value arguments.
But not these. For non-Bind(C) interfaces, vendors would continue with
their current implementation for this case.
> The TR would specify
> functions or structs to access and create such arguments. Preferably
> functions, so that vendors can provide them according to their Fortran
> conventions, instead of changing their Fortran conventions to conform to
> structs specified by the TR for the BIND(C) case.
Yes, that's the basic plan for assume-shape, allocatable, and pointer
arguments. At least to the extent that the vendor's current mechanisms
supply enough information to populate the structs on the C side.
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Bill Long longb at cray.com
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