Re: Call Backs

[Scott Klement <klemscot@xxxxxxxxxxxx>]

On Thu, 4 Jan 2001, Eric N. Wilson wrote:

> Hello everyone,
> 
> I am trying to figure out if there is a way to implement call backs
> with the EVAL/CALLP model rather than the CALLB model.
> 

Sure, there's a way...  unfortunately, there's no good way to implement a 
"header file" containing the prototype for the callback procedure (that I
know of) but...   you can certainly do a callback without using CALLB.

Here's a trivial example:

Source Member:  QRPGLESRC, FOREACH_H
     D ForEach         PR
     D   proc                          *   procptr value

Source Member: QRPGLESRC, FOREACH
       * Compile me with:
       *   CRTRPGMOD FOREACH SRCFILE(xxx/QRPGLESRC) DBGVIEW(*LIST)
       *   CRTSRVPGM FOREACH EXPORT(*ALL) ACTGRP(*CALLER)
      H NOMAIN

      D/COPY QRPGLESRC,FOREACH_H

      P ForEach         B                   Export  
      D ForEach         PI
      D   proc                          *   procptr value
      D CallMeBack      PR                  ExtProc(proc)
      D   Counter                     10I 0 value
      D X               S             10I 0

      C                   do        10            X
      c                   callp     CallMeBack(X)                
      c                   enddo

      c                   return
      P                 E


Source Member: QRPGLESRC, TESTFOR:
       ** Compile me with:
       **    CRTRPGMOD TESTFOR SRCFILE(xxx/QRPGLESRC) DBGVIEW(*LIST)
       **    CRTPGM TESTFOR BNDSRVPGM(FOREACH) ACTGRP(*NEW)
      D/COPY QRPGLESRC,FOREACH_H

      D DsplyNum        PR
      D   Num                         10I 0 value

      C                   callp     ForEach(%paddr('DSPLYNUM'))
      c                   eval      *inlr = *on

      P DsplyNum        B                   Export
      D DsplyNum        PI
      D   Num                         10I 0 value
      C                   dsply                   Num
      c                   return
      P                 E





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