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Date: Wed, 16 Jul 2008 13:25:57 -0500
From: Bill Long <longb@cray.com>
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Subject: Re: (j3.2006) (SC22WG5.3585)  OPTIONAL arguments and C interop
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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).

>
> Bill:
>
> 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 these.

> 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.

Cheers,
Bill

> Van
>
>
> _______________________________________________
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> J3@j3-fortran.org
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>   

-- 
Bill Long                                   longb@cray.com
Fortran Technical Support    &              voice: 651-605-9024
Bioinformatics Software Development         fax:   651-605-9142
Cray Inc., 1340 Mendota Heights Rd., Mendota Heights, MN, 55120