Re: Subprocedure Question

On Thu, 2005-09-01 at 18:48, Paul Morgan wrote:
> Isa,
> 
> Unless you use an export source member for each service program you can't
> get away with compiling a service program and not compiling the programs
> that use it.  Each service program has a signature just like files.  If you
> recompile the service program it's signature may change and the programs
> that use it blow up just as they would when a file format changes.  You can
> define the signature in the export source member so that even if you
> recompile the service program it's signature won't change.  That's
> equivalent to using LVLCHK(*NO) for a service program.
> 
> Paul

Man, I wish I had time to respond to this... check the archives, but
this isn't really true.  Real quick highlights:

1) A service program without an EXPORT is primarily useless, so you need
at least ONE.

2) The signature of a service program has precious little to do with the
*MODULEs contained within, but rather the exported procedure names and
their order.  If you don't change this, or if you only append to it
under a consistent signature, then programs using them will keep on
truckin.

3) Level checks are not the same as Signature validations.  LVLCHK(*NO)
would simply ignore any differences, but a hard-coded signature must
STILL match the compiled calling program.

Read these articles in order:
http://www.itjungle.com/mpo/mpo092503-story02.html
http://www.itjungle.com/mpo/mpo102303-story02.html
http://www.itjungle.com/mpo/mpo120403-story01.html
http://www.midrangeserver.com/fhg/fhg021104-story01.html
http://www.midrangeserver.com/fhg/fhg040704-story01.html

Gotta go...

Joel Cochran
http://www.rpgnext.com

> -- 
> Paul Morgan
> Senior Programmer Analyst - Retail
> J. Jill Group
> 100 Birch Pond Drive, PO Box 2009
> Tilton, NH 03276-2009
> Phone: (603) 266-2117
> Fax:   (603) 266-2333
> 
> Isa wrote
> 
> > I am thinking of
> > using service program to gain the ability to make changes without having
> > to recompile.
> 
>