Re: recursive calls

[Charles Wilt <charles.wilt@xxxxxxxxx>]

Well, first of all, it's more correct to say that RPG III programs
can't call themselves recursively.

An RPG IV program, if using ACTCGRP(*NEW), can call itself
recursively...but note that there's a big performance hit to using
ACTGRP(*NEW).  I seem to recall hearing that the cycle-less RPGLE
programs available in 6.1 and higher support recursion also, but I
can't seem to find a quick reference that confirms that...

OPM and ILE C programs can call themselves recursively.  As can OPM
and ILE CL programs.

You co-worker is correct regarding RPGLE sub procedures, they have
always supported recursion and each invocation gets a copy of it's
local variables.

You are correct in that adding the STATIC keyword, means that the
variable is shared between invocations...Bob Cozzi has a nice
article...
http://systeminetwork.com/article/recursion-recursion

HTH,
Charles


On Mon, Jan 31, 2011 at 9:55 AM, David FOXWELL <David.FOXWELL@xxxxxxxxx> wrote:
> Hi all
>
> Today, by accident I set up a job where program tried to call itself. We have one program that is duplicated in several libraries and LIBA/PGM  should have called LIBB/PGM. This was the first time I'd actually seen the error produce in this way. A coworker informed me that recursive calls were possible with subprocedures thanks to the fact that at each call, a separate storage area is allocated for each subprocedure. This is not the case for program calls. That means that if mySP calls mySP and there is a local variable V1,  there will be two adresses for V1, each containing a different value.
> I don't doubt my coworker, it's just that my reference is midrange.com.
>
> Is my information accurate? What happens to static variables in such subprocedure calls?
> --
> This is the RPG programming on the IBM i / System i (RPG400-L) mailing list
> To post a message email: RPG400-L@xxxxxxxxxxxx
> To subscribe, unsubscribe, or change list options,
> visit: http://lists.midrange.com/mailman/listinfo/rpg400-l
> or email: RPG400-L-request@xxxxxxxxxxxx
> Before posting, please take a moment to review the archives
> at http://archive.midrange.com/rpg400-l.