From: "Grein, Christoph" <christoph.grein@eurocopter.com>
Subject: Re: Problems with 'class, help anyone?
Date: Mon, 11 Nov 2002 10:03:59 +0100 (MET)
Date: 2002-11-11T10:03:59+01:00 [thread overview]
Message-ID: <mailman.1037005863.27483.comp.lang.ada@ada.eu.org> (raw)
> There is another way, with perhaps even less incompatibility: let's introduce
> third mode for a formal parameter - "return" mode (in addition to conventional
> "in" and "out"). That "return" may be applied to the procedure's first
parameter
> only, and it means the same as "out" mode, with single exception: if the first
> parameter of a procedure is in "return" mode then the procedure *may* be
called
> without the corresponding (first) argument, and in such a case it returns
value.
> For example:
>
> procedure Two_Fold(Result : return Boolean; Something : in Integer);
>
> X : Boolean;
> Two_Fold(X, 0); -- "return" as "out", procedure does not return value
>
> if Two_Fold(0) then -- first argument omitted, procedure returns value
> ...
> end if;
But an out parameter and a return value are not the same, i.e. they cannot
generally be interchanged!
Consider e.g.
function F return String;
vs.
procedure P (S: out String);
The former has no idea how long the object is that will get the result (if any),
the
latter takes the length from the parameter.
next reply other threads:[~2002-11-11 9:03 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2002-11-11 9:03 Grein, Christoph [this message]
-- strict thread matches above, loose matches on Subject: below --
2002-11-11 15:12 Problems with 'class, help anyone? Alexandre E. Kopilovitch
2002-11-12 12:20 ` Dmitry A. Kazakov
2002-11-09 0:11 Alexandre E. Kopilovitch
2002-10-29 4:48
2002-10-29 6:08 ` Jim Rogers
2002-10-29 19:10 `
2002-10-30 5:27 `
2002-10-30 7:49 ` Simon Wright
2002-10-30 8:13 ` Jim Rogers
2002-11-02 4:02 `
2002-11-05 2:40 `
2002-11-05 4:56 ` Jim Rogers
2002-11-05 17:25 ` Stephen Leake
2002-11-05 22:29 ` Robert A Duff
2002-11-06 8:54 ` Pascal Obry
2002-11-06 15:00 ` Georg Bauhaus
2002-11-06 17:18 ` Stephen Leake
2002-11-07 14:14 ` Georg Bauhaus
2002-11-06 15:19 ` Ted Dennison
2002-11-06 17:22 ` Stephen Leake
2002-11-07 10:32 ` Preben Randhol
2002-11-07 15:53 ` Stephen Leake
2002-11-06 13:48 ` John English
2002-11-07 15:07 ` Robert A Duff
2002-11-08 9:48 ` Dmitry A. Kazakov
2002-11-08 13:44 ` Robert A Duff
2002-11-08 14:27 ` Jean-Pierre Rosen
2002-11-09 18:40 ` Dmitry A. Kazakov
2002-11-11 9:51 ` Lutz Donnerhacke
2002-11-11 13:24 ` Dmitry A. Kazakov
2002-11-11 13:55 ` Lutz Donnerhacke
2002-11-09 19:02 ` Robert A Duff
2002-11-10 17:13 ` Dmitry A. Kazakov
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