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Date: Thu, 27 Apr 2006 17:51:19 +0200
From: Georg Bauhaus <bauhaus@futureapps.de>
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Subject: Re: procedural vs object oriented
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Date: 2006-04-27T19:50:51+02:00
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Pascal Obry wrote:
> Maciej Sobczak a �crit :
> 
>> In what way is this better or more certain than a dispatching call based
>> on the tag?
> 
> Static analysis is possible in this case.

But static analysis should be possible for the following
program, too, as long as for example `cons` returns references
to object of a known finite set of types derived from T...

At least possible in some defined set of cases, if slightly
more difficult.

procedure dis is

   package p is

      type T is tagged null record;
      type REF is access T'class;

      procedure op(x: T);

      type D1 is new T with null record;
      procedure op(x: D1);

      type D2 is new T with null record;
      procedure op(x: D2);
   end P;

   use P;

   function cons return REF;

   y: REF := cons;
begin
   op(y.all);
end;