pTAL Guidelines for TAL Programmers

Differences Between TAL and pTAL

pTAL Guidelines for TAL Programmers—527256-002

3-18

Dynamically Selected Procedure Calls

In TAL, you can dynamically select a procedure and call the procedure using a CODE

(DPCL) statement.

In pTAL, you cannot use CODE statements. Instead, use procedure pointers to

dynamically select a procedure to call, as in the following examples.

Example 3-11. Procedure Pointers

INT i;

REAL r;

REAL .EXT r2;

STRUCT s1 [0:9];

BEGIN

REAL PROCPTR f(x);

REAL x;

END PROCPTR;

END;

PROC p (i, j) EXTENSIBLE, CALLABLE;

INT i, .EXT j;

FORWARD;

PROCPTR a (a, b) EXTENSIBLE, CALLABLE;

INT a, .EXT b;

END PROCPTR;

PROCPTR c (p);

REAL PROCPTR p (x);

REAL x;

END PROCPTR;

BEGIN

END PROCPTR;

REAL PROCPTR d (x);

REAL x;

END PROCPTR;

@a := @p;

@d := @s1[2].f;

@s1[3].f := @d;

CALL c(d);

CALL a(1, r2);

r := d(r);

IF (s1[i].f(r)) < 1.0E0 THEN ...