Re: Value vs. Const

[rob@xxxxxxxxx]

That is the safe way.  Because in a simple program without subprocedures 
if you checked %parms and tried to initialize a variable not passed it 
would blow chunks on you.  However, in your subprocedure instead of using 
the local variable it uses the global variable.  Scary.

Better to stick with the logic:
if %parms>x;
 WorkVar=ParmVar;  // Use the passed parm if it was sent
Else;
  clear WorkVar;
EndIf;


Rob Berendt
-- 
"They that can give up essential liberty to obtain a little temporary 
safety deserve neither liberty nor safety." 
Benjamin Franklin 





Joel Cochran <jrc@xxxxxxxxxx>
Sent by: rpg400-l-bounces@xxxxxxxxxxxx
08/08/2003 08:03 AM
Please respond to RPG programming on the AS400 / iSeries
 
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        Subject:        Re: Value vs. Const


Just to clarify so others can learn from my mistake:

I *was* checking for whether or not the parm was passed using %parms(). 
My mistake came when the parm was not sent: I would then populate the
parm with a default value and use the parm as a local variable.  This is
the no-no I was referring to before.

Now by using const instead of value, I still use %parms() to check and
see if the parm was passed, but now I have a local variable with my
default value and I only change it if the parm was sent.  Now in my
program I'm using the lcoal variable instead and all is well.

The only reason that I specify const instead of value is simply as a
convention: now I cannot change the value of the parm to a default if
not sent: if I want this behavior I'm forced to use a true local
variable instead.

Clear as mud? :-)

Joel

On Thu, 2003-08-07 at 18:54, Scott Klement wrote:
> > 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...
> 
> Joel... there's nothing special about VALUE in this circumstance.   You
> should never reference ANY parameter that has not been passed.   It does
> not matter whether it's passed by VALUE or REFERENCE or CONST... you
> should *always* check with %parms to before using an "optional" 
variable.
> 
> 
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