Re: [BLACKBOX] Reading of OUT parameters: problem solved

From: [at]} <Rainer>
Date: Tue, 14 Apr 2009 14:53:23 +0200

----boundary-LibPST-iamunique-1487756794_-_-
Content-type: text/plain

I agree :-)

On the other hand I have quite often procedures with an OUT parameter
(e.g an error flag), which is set and subsequently read in the same
procedure body.
The current behaviour of OUT parameters frees me from creating an
addtional local variable, working on this variable, and assigning its
value to the OUT parameter at the end of the procedure body (which
could be forgtten easily).

Very convenient !

Best regards,
Rainer


Am 09.04.2009 um 09:23 schrieb Josef Templ:


> Strange!
> It seems that there is no difference between OUT and VAR
> except that pointers are set to NIL at procedure entry.
> This is kind of strange because IN params are read-only.
> So, for symmetry, one would expect OUT params
> to be write-only. At first, it looks like a bug in the compiler.
> But the language report is also unsymmetric and does not state
> that OUT params are write-only.
>
> I guess that in the initial CP design OUT params were supposed
> to be write-only indeed, but there have been some detail problems in
> the implementation that prevented this approach.
>
> - JT
>
>
> ----- Original Message ----- From: "Rainer Neubauer"
> <rainer.neubauer{([at]})nowhere.xy
> To: <BLACKBOX{([at]})nowhere.xy
> Sent: Wednesday, April 08, 2009 7:42 PM
> Subject: [BLACKBOX] Reading of OUT parameters: problem solved
>
>
>
>> Alexander,
>> thanks for clarification of things.
>> I unfortunately had a very tricky problem which took plenty of
>> time for debugging today.
>> Right now I suceeded in tracking down the problem to its root.
>> Thanks again for your help :-) :-)
>> Best regards,
>> Rainer
>> Am 08.04.2009 um 19:12 schrieb Alexander Iljin:
>>
>>> Hello!
>>>
>>> RN> thanks a lot for your instant (!!) reply :-)
>>>
>>> RN> So I suppose, it is possible to use OUT params as local
>>> variables in
>>> RN> the procedure body. Right ?
>>>
>>> Yes, of course. By the way, the contents of the variables is not
>>> strictly undefined: pointer variables are guaranteed to = NIL on
>>> procedure entry.
>>>
>>> ---=====---
>>> Alexander
>>>
>>>
>> ----
>> To unsubscribe, send a message with body "SIGNOFF BLACKBOX" to
>> LISTSERV{([at]})nowhere.xy
>>
>
>
> ----
> To unsubscribe, send a message with body "SIGNOFF BLACKBOX" to
> LISTSERV{([at]})nowhere.xy
>

----
To unsubscribe, send a message with body "SIGNOFF BLACKBOX" to LISTSERV{([at]})nowhere.xy----boundary-LibPST-iamunique-1487756794_-_-
Content-type: application/rtf
Content-transfer-encoding: base64
Content-Disposition: attachment; filename="rtf-body.rtf"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----boundary-LibPST-iamunique-1487756794_-_---

Received on Tue Apr 14 2009 - 14:53:23 UTC