Simulating Local Variables in RPG Programs

One of RPG's greatest faults, in my opinion, is the lack of local variables in subroutines. You can treat a variable (or indicator) as local to a subroutine by saving the variable's value upon entry to the subroutine, and restoring it when exiting. The code in 3 illustrates this. (Three dots indicate source code that would be needed for a complete program.)

One of RPG's greatest faults, in my opinion, is the lack of local variables in subroutines. You can treat a variable (or indicator) as local to a subroutine by saving the variable's value upon entry to the subroutine, and restoring it when exiting. The code in Figure 3 illustrates this. (Three dots indicate source code that would be needed for a complete program.)

Advantages of this technique are fewer chances for a subroutine to undesirably change a variable or indicator; fewer variables needed by the program; and easier copies of blocks of source from one program to another.

Simulating Local Varibles in RPG Programs

Figure 3 Simulating Local Variables in RPG

 ... 1 ...+... 2 ...+... 3 ...+... 4 ...+... 5 ...+... 6 ...+... 7 ... C EXSR SUB001 ... C SUB001 BEGSR C MOVE *IN31 SAV31 1 C MOVE NDX SAVNDX C *LIKE DEFN NDX SAVNDX ... C Z-ADD1 NDX C FLD LOKUP ARR,NDX 31 C *IN31 IFEQ *ON ... C MOVE SAV31 *IN31 C MOVE SAVNDX NDX C ENDSR ... 1 ...+... 2 ...+... 3 ...+... 4 ...+... 5 ...+... 6 ...+... 7