Re: Pointers, Parms, and all that (Was: DSPPGM API)

Hello David,

I haven't seen the difference documented but the terminology indicates 
different behaviour and 
section 1.5 of the ILE CEE API manual does explain how to handle 'omissable' 
parameters 
(although they mix the terminology and use the word 'omitted').

The CEExxxx APIs refer to 'omissable' parameters and the SPIR APIs refer to 
'optional' 
parameters.  'Optional' means you don't even have to specify them (note that 
the optional 
parameters are often specified in groups and are using a variable argument 
list) and 
'omissable' means pass a NULL pointer.  Not the clearest choice of terminology!

Regards,
Simon Coulter.

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//--- forwarded letter -------------------------------------------------------
> X-Mailer: Novell GroupWise 5.5
> Date: Wed, 28 Apr 99 08:43:49 -0600
> From: "David Morris" <dmorris@plumcreek.com>
> To: MIDRANGE-L@midrange.com
> Reply-To: MIDRANGE-L@midrange.com
> Subject: Re: Pointers, Parms, and all that (Was: DSPPGM API)

> 
> Simon,
> 
> Thanks for clearly stating these differences, this is not common knowledge 
> among RPG programmers.  I find it ironic that CEETSTA requires that a null 
> pointer be passed for its omissible parameter.  I know from experience that 
> not passing a null pointer when one is expected can cause your applications 
> to do strange things.
> 
> David Morris
> 
> >>> "Simon Coulter" <shc@flybynight.com.au> 04/28/99 04:34AM >>>
> 
> ..The primary difference between NULL parameters and the variable argument 
>list of the 
original 
> question is that a pointer is actually passed for the NULL parameter.  The 
>variable argument 
> list allows NOTHING AT ALL to be passed...
> 
> RPG IV (and other languages) allows parameters to be omitted and ILE allows 
>you to use the 
> CEETSTA API determine exactly which parameters were passed and operational 
>descriptors allow 
> you to determine information about those parameters.  These should work for 
>CLE programs but 
> nothing will assist with CL programs (other than the afore-mentioned MONMSG 
>MCH3601).
> 
> You probably know this but it may be educational to others.
> 
> Regards,
> Simon Coulter.

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