(j3.2006) reduction routine

[Robert W. Numrich]

An intrinsic object (reduction?, team?) with associated procedures:

type(reduction) :: x
real :: a, b

a = x%sum(b)




On Wed, May 19, 2010 at 10:06:03AM -0500, Bill Long wrote:
> Date: Wed, 19 May 2010 10:06:03 -0500
> From: Bill Long <longb at cray.com>
> To: fortran standards email list for J3 <j3 at j3-fortran.org>
> Subject: (j3.2006) reduction routine
> Reply-To: longb at cray.com,
> 	fortran standards email list for J3 <j3 at j3-fortran.org>
> 
> 
> Suppose you wanted to have an intrinsic that did a general reduction 
> operation, such as
> 
> call reduction (array, operation, result)
> 
> where there is an intrinsic or defined operation specified by the 
> 'operation' argument that is visible in the caller scope.
> 
> How would you actually specify the operation to the routine?  In the old 
> days, one would have just passed the name of the procedure that performs 
> the operation as the actual argument.  In the new OOP world, all you 
> would know is a generic specifier or a symbolic operator name.  You 
> could write
> 
>  call reduction (X, ".my_oper.", ans)
> 
> where you expect the compiler to look up (or, for polymorphic variables, 
> generate code to look up) the function corresponding to the operator 
> .my-oper. that is defined for a variable of the dynamic type of X, and 
> then pass that on to the actual reduction routine.  [Such a scheme would 
> only work for an intrinsic, so that the compiler 'knows' what to do.] 
> This is a bit clunky, but appears to work.
> 
> Is there a better method?
> 
> Cheers,
> Bill
> 
> 
> 
> -- 
> Bill Long                                           longb at cray.com
> Fortran Technical Support    &                 voice: 651-605-9024
> Bioinformatics Software Development            fax:   651-605-9142
> Cray Inc./Cray Plaza, Suite 210/380 Jackson St./St. Paul, MN 55101
> 
> 
> _______________________________________________
> J3 mailing list
> J3 at j3-fortran.org
> http://j3-fortran.org/mailman/listinfo/j3

-- 

			-bob numrich

--
Robert W. Numrich, PhD
Senior Research Associate
Minnesota Supercomputing Institute
587 Walter Library
117 Pleasant Street SE
Minneapolis, MN 55455

Tel:  612-624-4341