(j3.2006) reduction routine

[Bill Long]

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
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