TAL Programmer's Guide

CALL Statement
Controlling Program Flow
12–20 096254 Tandem Computers Incorporated
Omitting Parameters Conditionally
To omit a parameter or parameter pair conditionally, use the $OPTIONAL standard
function (D20 release or later) as described in Section 11, “Using Procedures.”
Calling Functions Callers usually invoke functions by using the function identifier in expressions, as
described in Section 11, “Using Procedures.” A caller can also invoke functions by
using a CALL statement, in which case the caller ignores the returned value.
Calling Procedures
Declared as Formal
Parameters
Callers can call procedures declared as formal parameters. If the called procedure is a
VARIABLE or EXTENSIBLE procedure, the caller must provide the appropriate
parameter mask. For more information, see Section 11, “Using Procedures.”
Passing Parameter Pairs You can pass parameter pairs in the CALL statement, as described in Section 17,
“Mixed-Language Programming.”