Re: Binder Language problems

[Gary L Peskin <garyp@xxxxxxxxxxxx>]

Nelson --

I don't mean to be dense here.  But let me give you an example so that
you can explain to me where my misunderstanding is.

I have a *PGM ("A") which consists of one module ("AM") which I recently
created using the following binder language:

STRPGMEXP PGMLVL(*CURRENT) LVLCHK(*YES)
  EXPORT SYMBOL('sym1')
  EXPORT SYMBOL('sym2')
ENDPGMEXP

After *PGM A is created, I create program B which calls procedure sym1.

Now, I enhance module AM and add a new entry point, called 'new1'.

Say I place this procedure before 'sym1' in AM.  By the way, I think the
RTVBNDSRC creates the exports in an order specified by the compiler. 
The C compiler places the exported symbols in the same order as they
appear in the program -- don't know about the other compilers.)

Now, I do a RTVBNDSRC, adding to my previous source.  After the command
runs, I get:

STRPGMEXP PGMLVL(*CURRENT) LVLCHK(*YES)
  EXPORT SYMBOL('sym1')
  EXPORT SYMBOL('sym2')
ENDPGMEXP
STRPGMEXP PGMLVL(*CURRENT) LVLCHK(*YES)
  EXPORT SYMBOL('new1')
  EXPORT SYMBOL('sym1')
  EXPORT SYMBOL('sym2')
ENDPGMEXP

The first four lines were in my binder source member from before I ran
the RTVBNDSRC command.

I change the binder source by replacing all but the last *CURRENT to
read *PRV so now the source looks like this:

STRPGMEXP PGMLVL(*PRV) LVLCHK(*YES)
  EXPORT SYMBOL('sym1')
  EXPORT SYMBOL('sym2')
ENDPGMEXP
STRPGMEXP PGMLVL(*CURRENT) LVLCHK(*YES)
  EXPORT SYMBOL('new1')
  EXPORT SYMBOL('sym1')
  EXPORT SYMBOL('sym2')
ENDPGMEXP

Since I haven't explicity specified a signature, the system will create
a different unique signature for each STRPGMEXP .. ENDPGMEXP block.  New
programs which call "A" will use the *CURRENT export block and will have
that signature embedded in them.

However, my old program "B" will still work, without recreating it,
because "B" references the first slot in the ORIGINAL export block
(which it locates based on the signature still embedded in "B") which is
still 'sym1'.

Programs compiled under an earlier signature will reference the earlier
signatures exports in that signatures ordinal order.  Are you overriding
the signature or not retaining old signatures?

Gary

Nelson Smith wrote:
> 
> Gary L Peskin wrote:
> 
> > You say that "To get clean compiles ...".  What happens if you just
> > change all of the STRPGMEXP commands, except the current one, to specify
> > PGMLVL(*PRV).  Why doesn't this result in a clean compile?
> >
> > Gary
> >
> I do that, but it is not enough because the new set of exports is placed
> at the end of the source member by RTVBNDSRC instead of at the beginning
> where the compiler requires it.
> 
> Also, it alphabetizes the exports rather than adding the new exports at
> the end.  While this will compile OK, it causes mismatches when programs
> compiled under an earlier signature try to call a procedure which used
> to be the first export, for example, and now gets a completely different
> procedure just because RTVBNDSRC moved a new one into export position
> one. Programs using the service program go by the position of the
> exports and not the name or size of parameters, etc.
> 
> I understand how to fix the problem, by moving the new source from the
> bottom of the source member to the top and by reorganizing the exports
> to put the new ones at the end. But if you have to do all that there is
> no point to using the RTVBNDSRC command.  It's easier to do it by hand.
> My question is am I doing something wrong or is RTVBNDSRC really that
> badly written?  Or has a PTF been issued to address this problem that I
> don't know about?
> --
> Nelson Smith
> "Standards are Wonderful....cause there's so many to choose from!"
> ncsmith@gate.net
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