Re: Overriding procedure as null

["Randy Brukardt" <randy@rrsoftware.com>]

<gautier_niouzes@hotmail.com> wrote in message 
news:77e909f6-9f24-4638-ba6a-1872e5a46580@googlegroups.com...
> Hello,
>
> I've just come across a little "legal" case that was easy to solve 
> practically, but I'm curious about what is "right" Ada.
>...
>    overriding procedure Write

You're not supposed to repeat "overriding" on bodies. It should be thought 
of like "generic" or aspects, which are not part of the profile. It's not 
illegal, but it's bad practice.

>     (Stream : in out Search_stream;
>      Item   : in     Ada.Streams.Stream_Element_Array) is
>    begin
>      null;  --  Something done in real case.
>    end;
>
>  begin
>    null;
>  end;
>
> GNAT (GPL 2017/Win32) compiles seamlessly.
> ObjectAda (9.2) issues, for the 2nd "Read":
>  test_overriding.adb: Error: line 18 col 24 LRM:8.3(26), Illegal to 
> override declaration in same region, prior declaration is Read at line 7
>
> It looks like OA considers the 2nd occurrence as a specification, not a 
> body - with "is null", it could be both actually.
> Who's right ?

A body freezes everything, and nothing can be overridden after. We had some 
issues with these rules, so it's possible that both are right (Ada 2005 and 
Ada 2012 may differ on these rules).

We've got an ARG meeting on Monday, so I don't have time to investigate 
further, sorry.

                 Randy.