Remove the need for procedure prototypes

This is another example of something in RPG that almost slipped by me. I now have a way not to have to define a procedure prototype in the procedures' member. All I need is the procedure, and the RPG compiler does its "magic" to do what ever it does to make this possible. This is made possible by the addition of a new control option and parameter in the procedure declaration.

The addition to the control option is a new option REQPREXP, which allows one of three values:

• *REQUIRE:  All procedures are required to have a prototype (DCL-PR)
• *WARN:  If a prototype is not found for a procedure a warning error, severity 10, is received when compiled
• *NO:  Procedure prototype is not required for the main and exported procedures

What does this look like?

Let me start with a RPG source member that is compiled to create a module:

01 **free 02 ctl-opt nomain REQPREXP(*REQUIRE) ; 03 /copy devsrc,prototypes 04 dcl-proc Procedure1 export ; 05 dcl-pi *n char(2) ; 06 Parm1 char(2) value ; 07 end-pi ; 08 end-proc ; 09 dcl-proc Procedure2 export REQPROTO(*NO) ; 10 dcl-pi *n char(2) ; 11 Parm2 char(2) value ; 12 end-pi ; 13 end-proc ;

Line 1: I only code in totally free RPG.

Line 2: Control options. NOMAIN means that there is no main procedure and does not use the RPG cycle. I have put the new control option in upper case. REQPREXP(*REQUIRE) tells the RPG compiler that all exported procedures must have a procedure prototype.

Line 3: I like to have my procedure protypes in an external source member that I can then copy into all the members where I need them. This source member only contains the prototype definition for Procedure1:.

**free // Prototypes dcl-pr Procedure1 char(2) ; *n char(2) value ; end-pr ;

Lines 4 – 8: The procedure Procedure1.

Lines 9 – 13: This is Procedure2. Notice that there is no procedure prototype for it! As this procedure has the REQPROTO(*NO) a prototype is not needed. What is given at the procedure level override what is in the control option.

I compile this to a module, and add the module to the binding directory MYBDNDDIR.

What do the programs that call these procedures look like? I have two examples:

1. "Traditional" cycle RPG program
2. Main procedure non-cycle RPG

This is the first of those two programs:

01 **free 02 ctl-opt bnddir('MYBNDDIR') ; 03 /copy devsrc,prototypes 04 dcl-pr Procedure2 char(2) ; 05 *n char(2) value ; 06 end-pr ; 07 dcl-s Value char(2) ; 08 Value = Procedure1('XX') ; 09 Value = Procedure2('') ; 10 *inlr = *on ;

Line 2: I am using a binding directory to hold the list of objects to bind to this program when it is compiled.

Line 3: Copy my prototypes source member into this member.

Lines 4 – 6: I have to have a procedure prototypes for Procedure2 for the RPG compiler to recognize it. If I do not I get the following:

Msg id Sv Number Seq Message text RNF7030 30 8 000800 The name or indicator PROCEDURE2 is not defined.

Lines 8 and 9: Both of the procedures are called without error.

Next example program uses the Main procedure:

01 ctl-opt main(Main) dftactgrp(*no) bnddir('MYBNDDIR') ; 02 /copy devsrc,prototypes 03 dcl-pr Procedure2 char(2) ; 04 *n char(2) value ; 05 end-pr ; 06 dcl-proc Main ; 07 dcl-s Value char(2) ; 08 Value = Procedure1('XX') ; 09 Value = Procedure2('') ; 10 end-proc ;

The above looks very similar to the previous "cycle" program the noteworthy differences are:

Line 1: As this is a main procedure program I need the MAIN and DFTACTGRP keywords.

Line 6: Start of the main procedure.

Line 10: End of the main procedure.

This program compiles and is called without error.

How about I want to use the REQPREXP control option to make every procedure have a prototype. The only change I need to show is:

02 ctl-opt main(Main) dftactgrp(*no) bnddir('MYBNDDIR') REQPREXP(*REQUIRE) ; 06 dcl-proc Main ;

Line 1: I added the REQPREXP(*REQUIRE) which requires all procedures to have a prototype, including the main procedure.

As the main procedure does not have a prototype when the source member is compiled the following error is given:

6 dcl-proc Main ; ======> aaaa *RNF0203 30 a NO PROTOTYPE IS SPECIFIED FOR AN EXTERNAL PROCEDURE OR PROGRAM, AND REQPREXP(*REQUIRE) IS SPECIFIED.

I don't want to have a prototype for the main procedure, I can just do the following:

02 ctl-opt main(Main) dftactgrp(*no) bnddir('MYBNDDIR') REQPREXP(*REQUIRE) ; 06 dcl-proc Main REQPROTO(*NO) ;

Line 6: By adding the REQPROTO(*NO) I am telling the RPG compiler that a prototype for this procedure is not required. As I said before by adding this to any procedure supersedes the REQPREXP in the control option.

It should come as no surprise that the program compiles without error.

I am not sure how I am going to use this. Do you have ideas? If so post them in the comments, below.

 

You can learn more about this from the IBM website:

• REQPREXP control option
• REQPROTO(*NO)

 

This article was written for IBM i 7.5 TR1 and 7.4 TR7.