Re: CONST and VALUE revisited

[Jeff Young <cooljeff913@xxxxxxxxx>]

So, provided my prototype and the PI of the called procedure match, if I specifiy CONST, the compiler will *never* allow the value to be changed in the called procedure?

If that is the case, then the only way I could have a problem is if I specified CONST in the prototype, but did not specify it in the PI of the called procedure and the procedure was in a service program.

Is this correct?
If so, then I do not understand the issue the OP was having.

Thanks,
 
Jeff Young 
Sr. Programmer Analyst
IBM -e(logo) server Certified Systems Exper - iSeries Technical Solutions V5R2 
IBM  Certified Specialist- e(logo) server i5Series Technical Solutions Designer V5R3
IBM  Certified Specialist- e(logo)server i5Series Technical Solutions Implementer V5R3 
  
 






________________________________
From: Adam Glauser <adamglauser@xxxxxxxxx>
To: rpg400-l@xxxxxxxxxxxx
Sent: Wednesday, January 28, 2009 2:14:24 PM
Subject: Re: CONST and VALUE revisited

> From: sjl <sjl_abc@xxxxxxxxxxx>
> I have this page bookmarked:
> http://www.web400.com/download/ilerpg/subprocedure_parameters2.htm>

Jeff Young wrote:
> Based on that info, CONST is enforced by the compiler ONLY if you are using sub-procedures.
> If you are using an external service program or just another program, then using VALUE is the only way to ensure that the parameter will not be changed on return from the call.
>
> Is this a correct summary?

Not exactly.  It's more correct to say that CONST is only enforced if 
the called code uses a prototype to describe its parameters.  Of course, 
prototype mismatches can throw a wrench in things, but that's what /copy 
is for.

Programs cannot receive parameters by value, at least up to V5R4.  I 
don't know if the user-defined entry procedure feature in V6R1 changes that.


David Gibbs wrote:
> IIRC, it won't even let you get the address of a parameter passed as
> const (using %addr), so you can't do direct memory manipulation via a
> pointer.

Nor can you pass it to a program or procedure that does not specify 
CONST or VALUE, even if you use CALL+PARM.