pTAL Reference Manual (H06.03+)

Procedures, Subprocedures, and Procedure
Pointers
HP pTAL Reference Manual—523746-005
14-32
Declaring PROCPTRs as Formal Parameters
Declaring PROCPTRs as Formal Parameters
The compiler:
•
Ensures that the procedure attributes and parameter data types of procedures
passed as actual parameters match those defined in the formal parameters of the
called procedure
•
Builds parameter masks for calls to VARIABLE procedures and EXTENSIBLE
procedures
You can declare a formal parameter to be a PROCPTR as in the following example:
PROC p(pp);
PROCPTR pp(i, j);
INT i, j;
END PROCPTR;
BEGIN
...
END;
An @ character in front of the actual parameter is:
•
Not allowed if the formal parameter is a PROC or a PROCPTR
•
Required if the formal parameter is a PROCADDR
Example 14-16. PROCPTRs as Formal Parameters
PROC a(i);
INT i;
EXTERNAL;
PROC b(p);
PROCPTR p(a);
INT a;
END PROCPTR;
EXTERNAL;
PROC c(pa);
PROCADDR pa;
BEGIN
END;
PROC d;
BEGIN
CALL b(a); ! OK
CALL b(@a); ! ERROR: @ character is not valid
CALL c(a); ! ERROR: @ character is required
CALL c(@a); ! OK: @ character is required
END;