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From: Ted Dennison <dennison@telepath.com>
Subject: Re: I want 'Class'Input back!
Date: 1999/10/26
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References: <7u0as6$fmm$1@nnrp1.deja.com> <3814EF36.3D82D483@rational.com>
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Date: 1999-10-26T00:00:00+00:00
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In article <3814EF36.3D82D483@rational.com>,
  Mark Lundquist <mark@rational.com> wrote:

>          function Input
>                      (Stream : access
Ada.Streams.Root_Stream_Type'Class) return T is
>          begin
>              return (T_Base'Input (Stream) with null record);
>          end Input;

I have to admit I'm not too sure what is going on here. The "return"
line is particularly perplexing. what does "T_Base'Input(Stream) with
null record" do?

>          procedure Output (Stream : access
Ada.Streams.Root_Stream_Type'Class;
>                            Item : in T) is
>          begin
>              T_Base'Output (Stream, T_Base (Item));
>          end Output;

This OTOH looks completely wrong. 'Output doesn't write the type's
tag to the output stream like 'Class'Output does. How is 'Class'Input
going to know which 'Input routine to dispatch to, if it doesn't know
the type's tag?

--
T.E.D.


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