Aspect location in expression function.

Aspect location in expression function.

[Blady]

Hello,

I'm puzzled when I want to changed a function body with aspects to an 
expression function, for instance:

function Length (S : Some_Tagged_Tyoe) return Natural
   with Pre => S.Valid
   is
   begin
   return S.Length;
   end;

have to be changed in:

function Length (S : Some_Tagged_Tyoe) return Natural
   is (S.Length)
   with Pre => S.Valid;

The location of the aspect has moved to the end.

I'd like simply replace the begin block by the expression, as:

function Length (S : Some_Tagged_Tyoe) return Natural
   with Pre => S.Valid
   is (S.Length);

What could be any reasons not to permit it?

Thanks, Pascal.

Re: Aspect location in expression function.

[J-P. Rosen]

Le 14/05/2022 à 13:47, Blady a écrit :
> Hello,
> 
> I'm puzzled when I want to changed a function body with aspects to an 
> expression function, for instance:
> 
> function Length (S : Some_Tagged_Tyoe) return Natural
>    with Pre => S.Valid
>    is
>    begin
>    return S.Length;
>    end;
> 
> have to be changed in:
> 
> function Length (S : Some_Tagged_Tyoe) return Natural
>    is (S.Length)
>    with Pre => S.Valid;
> 
> The location of the aspect has moved to the end.
> 
> I'd like simply replace the begin block by the expression, as:
> 
> function Length (S : Some_Tagged_Tyoe) return Natural
>    with Pre => S.Valid
>    is (S.Length);
> 
> What could be any reasons not to permit it?

What you say is logical if you think of an expression function as a 
body; however, it is more like a specification (it can appear in a 
package spec, although it can complete a specification), so the place 
where the aspect appears makes sense. And it would be confusing to allow 
the aspect in two different places. It is the same for separate bodies 
of subprograms.

-- 
J-P. Rosen
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