Re: stopping a loop iteration without exiting it

["Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de>]

On 2018-01-04 20:46, Robert A Duff wrote:
> "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de> writes:
> 
>> P.P.S. When-for-everyone is long overdue:
>>
>>     goto <label> when <condition>;
>>     return [<result>] when <condition>;
>>     raise <exception> [with <message>] when <condition>;
> 
> Those were all proposed for Ada 9X.  They were rejected,
> IIRC, because they're mere "nice to haves", and the mood
> was generally "simplify by removing features".  (Since the
> above make the language more uniform, adding them arguably
> simplifies.)

Yes, if you cannot reject it for being too complex, then blame it too 
simple. (:-))

> I don't think anyone ever suggested:
> 
>      X := X + 1 when X < Integer'Last; 

I thought about really important cases, but could not invent syntax:

    if X in T'Class then
       declare
          Same_X : T'Class renames T'Class (X);
       begin
          ...
       end;
    end if;

and

    if P /= null then
       declare
          X : P_Type renames P.all;
       begin
          ...
       end;
    end if;

and

    declare
       X : Access_To_Parent_Class := new Derived;
       Same_X : Derived renames Derived (X.all);
    begin
       ...
       return X; -- Parent's class result
    end;

a combination of a test and a renaming.

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