Re: Ada2012 : Expression functions and extended return statements

[Martin <martin@thedowies.com>]

On Jan 6, 9:45 am, stefan-lu...@see-the.signature wrote:
> On Fri, 6 Jan 2012, Martin wrote:
> > Also, on the topic of extended return statements...
>
> > What's the rational for having to explicitly repeat the return type?
> > Seems rather redundant to my eyes. I wouldn't have minded:
>
> I guess, this is because the object actually returned may not necessarily
> be of exactly the same type of subtype as the declared return type -- like
> the ordinary return statement. See the following examples:
>
>    function Characters(I: Integer; Filler: Character := '_') return String is
>    begin
>       return Result: String(1..I) := (others => Filler) do
>         return;
          ^^^^^^^

I think you mean
        null;
or
        return Result: String(1..I) := (others => Filler);


>       end return;
>    end Characters;
>
>    type T is tagged record I: Integer; end record;
>    type S is new T with record J: Natural; end record;
>
>    function Fun(N, M: Natural) return T'Class is
>    begin
>       return Result: S do
>         Result.I := M;
>         Result.J := N;
>       end return;
>    end Fun;
>
> --
> ---- Stefan.Lucks (at) uni-weimar.de, University of Weimar, Germany  ----
>     <http://www.uni-weimar.de/cms/medien/mediensicherheit/home.html>
> ------  I  love  the  taste  of  Cryptanalysis  in  the  morning!  ------


Ah ok, yes, that makes sense...thanks. Never had need of
this...yet! :-)

I still think it would be nice to have a short-hand e.g. 'return
Result : <> do'. If anything it would then draw the eye to the more
interesting case when the 2 are different.

-- Martin