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From: "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de>
Subject: Re: Dispatch on the result still does not work?
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Date: Sat, 11 Jul 2009 17:19:16 +0200
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On Sat, 11 Jul 2009 06:36:48 -0700 (PDT), Hibou57 (Yannick Duchêne) wrote:

> On 11 juil, 14:20, "Dmitry A. Kazakov" <mail...@dmitry-kazakov.de>
> wrote:
>> Conceptually there is no any difference between parameters and results of a
>> subprogram
> 
> IMHO, there is a difference. A result is something created, not
> something assigned to.
>
> Until the function creates the return value, the return value does not
> exist.

(You mean here "the return object". The value has existed and continues to
exist. Value is a property of the type, e.g. 123 exists even if you don't
have any Integer variable holding it.)

> Now, what if the function is invoked for a formal parameter which is,
> let say “ Parameter : T'Class ” ?

The actual object is converted to T'Class (per view conversion). This is a
different case,... or not. All depends on how to treat the assignment
statement.

> Conceptually, returning a result from a function, is not an
> assignment, this is.... just returning a result from a function. If it
> later turns into an assignment, this is a matter of the usage of the
> function, not a matter of the work of the function. As a proof, this
> happens only later, after the function was invoked, and more than
> that, the result may not be assigned to any variable.

Well, I used to think the way like you do until Ada 2005 introduced limited
aggregates and initialization of limited objects and their components using
functions... (:-))

-- 
Regards,
Dmitry A. Kazakov
http://www.dmitry-kazakov.de