(j3.2006) (SC22WG5.3593) Assumed-type and Assumed-rank extensions for C Interop TR.

[Bill Long]

Jim Xia wrote:
>
> Bill Long <longb at cray.com> wrote on 07/25/2008 02:38:50 PM:
>
> > > The basic problem is Fortran side can not use this type directly.  If
> > > the procedure is defined in Fortran for C, then how can a Fortran
> > > programmer "map" this dummy argument to real Fortran data type.
> >
> > In what way does C_F_POINTER fail to solve this problem?  It was
> > explicitly designed to be used on the Fortran side to give a Fortran
> > type, type parameters, and shape to a block of memory pointed to by a C
> > address.
>
>
>
> Read what's written in C_F_POINTER on page 394
>
>
> (1) If the value of CPTR is the C address of an interoperable data
> entity, FPTR shall be a data pointer with type and type parameters
> interoperable with the type of the entity. In this case, FPTR
> becomes pointer associated with the target of CPTR. If FPTR is
> an array, its shape is specified by SHAPE and each lower bound
>

Option 1 is the one we want to apply.  If the wording of the draft is 
such that these conditions are not met, then fixes are needed.
>
>
> In any case, it is asking for the pointer association.  I don't see 
> how TYPE(*) can fit in here yet.
>

The FPTR argument was declared integer,pointer,dimension(:),  so it is 
clearly a pointer. The effect of executing c_f_pointer is to cause that 
pointer to be associated with the target of CPTR, which in this case is 
the buffer that was declared type(*).    C_F_POINTER does not ask for 
pointer association, it causes pointer association.

Cheers,
Bill

>
> Cheers,
>
> Jim Xia
>
> RL Fortran Compiler Test
> IBM Toronto Lab at 8200 Warden Ave, Markham, On, L6G 1C7
> Phone (905) 413-3444  Tie-line 313-3444
> email: jimxia at ca.ibm.com
> D2/YF7/8200 /MKM

-- 
Bill Long                                   longb at cray.com
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