The Template of the Dummy Argument

 

Here we describe precisely how to determine the template with which the dummy argument is ultimately aligned:

Templates are not passed through the subprogram argument interface. A dummy argument and its corresponding actual argument may be aligned to the same template only if that template is accessible in both the caller and the called subprogram either through host association or use association. In any other case, the template with which a dummy argument is aligned is always distinct from the template with which the actual argument is aligned, though it may be a copy (see Section 4.4.2). On exit from a procedure, an HPF implementation arranges that the actual argument is aligned with the same template with which it was aligned before the call.

The template of the dummy argument is arrived at in one of three ways:

• If the dummy argument appears explicitly as an alignee in an ALIGN directive, its template is the align-target if the align-target is a template; otherwise its template is the template with which the align-target is ultimately aligned.
• If the dummy argument is not explicitly aligned and does not have the INHERIT attribute (described in Section 4.4.2 below), then the template has the same shape and bounds as the dummy argument; this is called the natural template for the dummy.

  (Thus, all the examples in Section 4.3 use the natural template.)

• If the dummy argument is not explicitly aligned and does have the INHERIT attribute, then the template is ``inherited'' from the actual argument according to the following rules:
  • If the actual argument is a whole array, the template of the dummy is a copy of the template with which the actual argument is ultimately aligned.
  • If the actual argument is an array section of array where no subscript is a vector subscript, then the template of the dummy is a copy of the template with which is ultimately aligned.
  • If the actual argument is any other expression, the shape and distribution of the template may be chosen arbitrarily by the language processor (and therefore the programmer cannot know anything a priori about its distribution).

  In all of these cases, we say that the dummy has an inherited template.