RE: A different kind of persistence?

["Bob Cozzi" <cozzi@xxxxxxxxx>]

Barbara,
Sounds like I'd like you to add NOMAIN(*REINZ) to the list of things for
V5R4. And of course this would only "work" when being bound to a *PGM not
*SRVPGM program.

NOMAIN(*REINZ) - Causes the global variables in the module to be reset to
the initial values when the entry module sets on *INLR and returns to the
caller. When the program containing this module is compiled to a named
activation group and called a second time after setting on *INLR, the global
variables in all NOMAIN(*REINZ) modules are reset.

-Bob Cozzi


-----Original Message-----
From: rpg400-l-bounces@xxxxxxxxxxxx [mailto:rpg400-l-bounces@xxxxxxxxxxxx]
On Behalf Of Barbara Morris
Sent: Tuesday, January 11, 2005 4:35 PM
To: rpg400-l@xxxxxxxxxxxx
Subject: Re: A different kind of persistence?

Dane Cox wrote:
> 
> Not withstanding that LR is specific to RPG (after all, this is an RPG
> specific list), was there a compelling reason to stop shy of
> re-initializing all of the statically bound modules that make up the
> compiled object?  

Nothing even starts re-initializing modules, so it can't stop shy of
doing all of them.  There's just a bit of code generated by the RPG
compiler into every RPG module.  Something like this:

            if static_init_flag = *on;
                fld1 = 0;
                fld2 = *blanks;
                etc.
                open files;
                etc.
                static_init_flag = *off;
                run *inzsr;  (not generated for nomain modules)
            endif;
            ...
            generated for non-nomain modules only:
            if *inlr = *on;
                close files;
                static_init_flag = *on;
            endif;           
            ...
            return;

> Since the 'main' module remains resident until the AG
> is destroyed, apparently there was a requirement to re-initialize these
> 'main' modules at one time or another and LR was used as that mechanism?

This behaviour of LR causing re-initialization predates the concept of
multiple-module programs by a couple of decades.

> ... I mean, from what I am hearing no
> other programs or modules can use them since they are specific to the
> 'main' that they are bound to...no?  Again, I'm just trying to
> understand some of the advantages or disadvantages of these
> mechanics...LR seems a little 'incomplete' to me...in this circumstance.

You're confusing compile time with run time.  A module may or may not be
reused to be part of one or more programs, at compile time.  There is no
concept of persistence here.  At run time, a given module in a program
may be called one or more times in the same activation group.  The
"persistence" of the module is actually the persistence of its static
storage, which is allocated for the lifetime of the activation group. 
There is also the persistence of the _values_ of the static storage;
those persist until something changes them, either the logic of the code
that you write, or the logic of the code that the compiler generates on
your behalf.

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