Re: V6R1 Info

Jon Paris wrote:

On 30-Jan-08, at 2:55 PM, midrange-l-request@xxxxxxxxxxxx wrote:

RPG has had recursion for more years than I have been with the platform.
Guessing it came in V3R1 when ILE came.

I just checked. I think you are right ;)

It arrived with subprocedures in V3R2/V3R6 - V3R1 RPG IV did not support recursion.

But it wasn't supported for programs until V6R1. (Not counting the pseudo-recursion that you could get with *NEW.)

In V6R1, you can have an RPG module with a new type of main procedure called a linear-main procedure, as opposed to a cycle-main procedure. An RPG program created with this new type of main procedure can be called recursively.

Basically, you code the MAIN keyword on the H spec saying which procedure will be the main procedure, then you code the procedure pretty much like an ordinary subprocedure. The difference is that the prototype has EXTPGM instead of EXTPROC.

H main(mypgm)
D mypgm pr extpgm('MYPGM')

// Main procedure for program MYPGM
P mypgm b
. . .
if something;
// make a recursive call to _program_ MYPGM
mypgm();
endif;
. . .
// when it gets here, it returns automatically
P e