RE: Allocate field with options(*nopass :*omit)

["Bob Cozzi" <cozzi@xxxxxxxxx>]

The following can be used to retrieve a non-const ptr to a const parameter.
Use at your own risk--no warranty is expressed or implied and none is given.

Create a C module using PDM option 15 or CRTCMOD (no special parameter needed)
from the following source member:
 // Mbr: GETCONST
#include <stdio.h>

void* GetConstPtr(const char* pConst);
void* GetConstPtr(const char* pConst)
{
     return (void*)pConst;
}

Create the test case RPG IV source member using PDM option 15.
Then do:
 CRTPGM TESTCONST  MODULE(TESTCONST GETCONST)
Start debug and set a break point at the call to myProc(qData:%len(qData)).
Step to the next line and look at the field named GDATA. The subprocedure which
accepts it as a constant value, actually changes the value of the GDATA variable
using a non-const ptr. 

        //  Mbr: TESTCONST
     H BNDDIR('QC2LE')

     D GetConstPtr     PR              *   ExtProc('GetConstPtr')
     D  szConstData                  64A   Const

     D gData           S             20A   Inz('Cozzi Sucks!')

     D myProc          PR
     D  someData                     64A   Const OPTIONS(*VARSIZE)
     D  ndataLen                     10I 0 Const

      /free
          myProc(gData:%len(gdata));
          *INLR = *ON;
      /end-free
     P myProc          B
     D myProc          PI
     D  someData                     64A   Const OPTIONS(*VARSIZE)
     D  ndataLen                     10I 0 Const

     D  pLocalPtr      S               *
     D  localData      S             64A   Based(pLocalPtr)

      /free
           pLocalPtr = GetConstPtr(someData);
           if (pLocalPtr <> *NULL);
              %subst(localData:1:nDataLen) = 'No he doesn''t!';
           endif;
           return;
      /end-free
     P myProc          E

-Bob Cozzi
www.iSeriesTV.com
Ask your Manager to watch iSeriesTV.com


-----Original Message-----
From: rpg400-l-bounces@xxxxxxxxxxxx [mailto:rpg400-l-bounces@xxxxxxxxxxxx] On
Behalf Of Bob Cozzi
Sent: Thursday, August 31, 2006 4:20 PM
To: 'RPG programming on the AS400 / iSeries'
Subject: RE: Allocate field with options(*nopass :*omit)

That's what I remember, but I thought it didn't work in V5.1?
The other thing I think "works" now and didn't previously was this (in C):

void* GetConstPtr(const void* pConst)
{
     
     return pConst;
}

-Bob Cozzi
www.iSeriesTV.com
Ask your Manager to watch iSeriesTV.com


-----Original Message-----
From: rpg400-l-bounces@xxxxxxxxxxxx [mailto:rpg400-l-bounces@xxxxxxxxxxxx] On
Behalf Of Barbara Morris
Sent: Thursday, August 31, 2006 3:57 PM
To: rpg400-l@xxxxxxxxxxxx
Subject: Re: Allocate field with options(*nopass :*omit)

Bob Cozzi wrote:
> It depends on what release you're targeting the compile.
> If you're on V5.2 or later, I believe it works. It should/does work on V5.3.
> It was supposed to work on V3.7 but nobody complained until long after V5.1
was
> out.

You can't assign the value of %addr(constparm) on any release.  The
change made in v5r1 was to allow %addr(constparm) to be used in a
comparison.  (Not sure what you're remembering about v3.7 and "long
after v5.1".)