CODEWITHSUNDEEP
stored-proceduresprototypeibm-midrangerpgle
LppEdd
LppEdd

Reputation: 21134

Prototype and interface in RPGLE programs/procedures

Reading IBM documentation I become a little bit confused about how to correctly write a program/procedure entry point.

Especially reading this https://publib.boulder.ibm.com/iseries/v5r2/ic2924/books/c092508410.htm
I see:

The prototype with the matching name must precede the procedure interface in the source

And here http://www.ibm.com/support/knowledgecenter/ssw_ibm_i_72/rzasd/freeinterface.htm
I read:

If you do not specify a prototype for a cycle-main procedure, you use *N as the name for the procedure interface

So I code a new program this way:

CTL-OPT ...

DCL-PI *N;
  P1 CHAR(2);
  P2 CHAR(2) CONST;
  P3 CHAR(2) CONST;
  P4 CHAR(1) CONST;
  P5 PACKED(7) CONST;
  P6 POINTER;
  P7 INT(5);
END-PI;

...

and it compile and run fine.
So what I'm asking is, when and why should I specify a prototype before the interface?

Upvotes: 2

Views: 2917

Answers (3)

Barbara Morris
Barbara Morris

Reputation: 3674

About having to manually open and closE files ...

Files are automatically opened for all files defined in RPG modules, unless the USROPN keyword is specified. This applies to global files in any type of module, and for local files in a subprocedure.

What does differ is when or if the file is automatically closed, depending on where the file is declared. Static files in subprocedures or global files in NOMAIN or linear main modules are never automatically closed until the activation group ends. Automatic files in subprocedures get closed when the subprocedure ends, and global files in cycle main modules get closed according to the RPG cycle.

Upvotes: 2

jmarkmurphy
jmarkmurphy

Reputation: 11473

The short answer to your question is always create a prototype for an RPG4 program. It may be optional, but you might need it down the road.

I have begun using linear main procedures for programs rather than cycle main. You do this by including ctl-opt Main(procname) at the head of the program. I also put my prototypes in separate source files. That way I can easily include them with /copy directives which has a side effect of collecting external program and service program dependencies near the top of my programs. I prefer to put all prototypes in a separate source file, named the same as the program source. Or for service programs, I name it the same as the service program. But some places I have worked will put a suffix at the end of the prototype and store it in the same service program with the program or module source. The nice thing at v7.1 is that you don't have to define prototypes for internal procedures, just the ones that are exported. At the program level, that is the main procedure, and while that is strictly not required, I always create that prototype in it's own source, because you never really know if you are going to want to call that program from somewhere else at some time in the future. Also while it is not required for you to include the prototype in the program itself, doing so is a good way to verify that the prototype is valid.

Upvotes: 3

LppEdd
LppEdd

Reputation: 21134

So, going in details and looking at the changes in 7.1 > (for full free form syntax) I found this:
What's New in 7.1?

If a program or procedure is not called by another RPG module, it is optional to specify the prototype. The prototype may be omitted for the following types of programs and procedures: A program that is only intended to be used as an exit program or as the command-processing program for a command A program that is only intended to be called from a different programming language A procedure that is not exported from the module A procedure that is exported from the module but only intended to be called from a different programming language.

It's worth having a good read of all the "What's new" pages!

Upvotes: 2

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