RE: Parameters of the Call elementary action

Emmanuel BEUQUE (ebeuque@pratique.fr)
Mon, 14 Apr 1997 12:15:20 +0200

À (At) 17:24 +0000 11/04/97, Xavier MARIE écrivait (wrote) :
>Emmanuel wrote:
>>>On the other hand, I think that the MHEG-6 people have a more definitve
>>>answer to the question, since they deal quite much with parameter
>>>passing.
>>
>>Yes, and there, I think that MHEG-6 should clarify things and fix them for
>>everybody.
>
>
>No doubt MHEG-6 will clarify it for InterchangedProgram. More than that:
>MHEG-6 activity is the reason why the changes were proposed and accepted
>in Tampere. With the intent that you mention (i.e. since passing Variable
>parameters (by value, i.e. as IN pars) practically allows to return value
>thanks to
>Set/GetVariable, there is no reason to have distinct OUT parameters of
>Integer
>(or any other) type - i.e. technically there is no passing by reference.
>But MHEG-6 will not clarify anything for RemoteProgram and ResidentProgram,
>which are beyond its scope.

That's true that MHEG-6 is only concerned in interchanged programs but,
since parameter passing mechanism is defined in MHEG-5 Program class and
inherited as is by all Resident, Remote and Interchanged program, we could
consider that things clarified for Interchanged apply in fact to the whole
Program class and consequently also apply for Remote and Resident.

In other words, MHEG-5 theoretically doesn't allow MHEG-6 to define a
parameter passing mechanism that would not apply also to Resident and
Remote program, or I missed something.

Anyway, as far as the initial question of Christine is concerned, I would
considered that parameters of program are passed by value ("Parameters
shall be set to a list of values corresponding..."). Therefore, if one
wants to pass a value stored in a variable, he must put an indirect
reference. Giving the object reference of this variable alone should be
considered I think, as an ObjectRef value, that points to a variable of a
type that the program should specify, and the program could then be allowed
to get/set this variable via the MHEG-5 API.

I don't see how we could think differently because, if so, it would be
impossible to pass an ObjectRef value directly, without storing it first in
a useless ObjectRef variable...

Just my point of view anyway.
Regards,

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