Re: Pondering what rationale behind record type

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

On Tue, 10 May 2011 12:12:10 +0200, Georg Bauhaus wrote:

> On 10.05.11 09:45, Dmitry A. Kazakov wrote:
>> On Tue, 10 May 2011 00:03:37 +0200, Georg Bauhaus wrote:
>> 
>>> First, in the phrase "end X", the "X" part can usually be omitted.
>> 
>> That is another fix to do: a default profile which would forbid omitting
>> the name. I saw no Ada program in my life which omitted names in the ends.
>> 
>>> So whenever we put "record" (or "case", or "if", etc) after an "end",
>> 
>> These are anonymous constructs.
> 
> Though a loop can have a name.
> 
> Anything wrong with (i.e. makes you shudder)
> 
>    Label_A: loop
>      ...
>    end loop Label_A;
> 
> ?

loop A do
   ...
end A;

>> The only reason why record bracket should
>> not contain its name is when there is no name, e.g. as Randy has pointed
>> out, in an anonymous record type. They are illegal in Ada, but an imaginary
>> example could be:
>> 
>>    function Get_Token (File : File_Type) return
>>       (Matched : Boolean; Length : Positive) record
>>          ...
> 
> In order to be competitive in the current discussion,
> pro "end [X]", the example would have to be
> 
>    type Get_Token is function (File : File_Type) return
>        ((Matched : Boolean; Length : Positive) record
>            case Matched is
>              when True => Token : String (1..Length);
>              when False => null;
>            end case;
>         end record)
>    end Get_Token;

No, Get_Token would be a function-type. E.g.

   type Func is function (X : Float) return Float;

Then

   function Integrate (...; What : Func) return Float;

Which could be be anonymous as well:

   function Integrate (...; What :  function (X : Float) return Float)
      return Float;

Or the example with Get_Token:

   procedure Parse
   (  File : File_Type;
      Get_Token : function (File : File_Type) return
         ((Matched : Boolean; Length : Positive) record
            case Matched is
              when True => Token : String (1..Length);
              when False => null;
            end case;
         end record
   );

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