Re: Value vs. Const

[Joel Cochran <jrc@xxxxxxxxxx>]

One caveat that Barbara Morris pointed out to me is that using "value"
and "options(*nopass)" on the same variable can be dangerous.  If you
want a variable to be *nopass and still take advantage of the VALUE
benefits, then use CONST...

 // This is a no-no...
d myProto             pr
d  parm1                         1a   value
d  parm2                        10a   value varying
d  parm3                        10a   value varying options(*nopass)

 // Do this instead...
d myProto             pr
d  parm1                         1a   value
d  parm2                        10a   value varying
d  parm3                        10a   const varying options(*nopass)

Now you should use a local variable with a default value, and populate
it with the parm3 value only if %parms() indicates it was passed.


Joel
http://www.rpgnext.com


On Thu, 2003-08-07 at 16:27, rob@xxxxxxxxx wrote:
> Normally I use CONST.  However if you find that in the subprocedure that 
> the first thing you are doing is copying the variable over to another one 
> so that you may modify it, then I'd use VALUE.  I think we both understand 
> that this modification is not passed back to the main program unless we 
> omit both VALUE and CONST.
> 
> An example of 'maybe' a good use of VALUE:
> 
> /free
>   parm=%abs(parm);
>   return parm*25;
> /end-free
> 
> But if you're doing:
> /free
>   WorkVar=%abs(parm);
>   return parm*25;
> /end-free
> 
> Then you could get by with CONST.  But then you have the overhead of 
> another variable, etc.  And, of course I realize that you could do:
> /free
>   return %abs(parm)*25;
> /end-free
> 
> just trying an example.
> 
> 
> Rob Berendt