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From: "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de>
Newsgroups: comp.lang.ada
Subject: Re: Pass by reference
Date: Sat, 10 Apr 2004 12:49:34 +0200
Organization: At home
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Date: 2004-04-10T12:49:34+02:00
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Dan McLeran wrote:

>> This need not to be tagged, because there is no dispatching subroutines
>> here. A rough C++ equivalent of a tagged type is a class with virtual
>> functions.
> 
> Quite right. This is a better example:
> 
> struct Silly
> {
>     virtual int Get()
>     {
>         return i;
>     }
> private:
>     int i;
> };

You have to add a friend function, because in C++ Silly will be passed to
Get() by reference as in Ada:

   type Silly is tagged private;
   function Get (Object : Silly) return Integer;

private
   type Silly is tagged record
      I : Integer;
   end record;

So the difference between C++ and Ada is rather marginal here. But as I
said, I think it would be better to leave the choice to the compiler (in
the case of non-limited tagged types.)

-- 
Regards,
Dmitry A. Kazakov
www.dmitry-kazakov.de