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From: Jeff Carter <carter@innocon.com>
Subject: Re: OO, C++, and something much better!
Date: 1997/01/14
Message-ID: <32DB90DC.41C67EA6@innocon.com>#1/1
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references: <E3xprM.4pB@syd.csa.com.au> <E3z0zy.9qL@syd.csa.com.au>
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Date: 1997-01-14T00:00:00+00:00
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Don Harrison wrote:
> 
> The following is a valid Ada83 program (and presumably valid Ada95):
> 
> procedure Test_Type_Hole is
>   subtype Sub_Integer is Integer range 1 .. 10;
>   I: Integer;
>   S: Sub_Integer;
> 
>   procedure Use_Subtype (S: Sub_Integer) is
>   begin
>     null;
>   end;
> 
> begin
>   I := 1000;
>   Use_Subtype (I);       -- System Invalid call - raises
>                          -- Constraint_Error at runtime.
> end Test_Type_Hole;
> 
> So, contrary to your claim, Ada *does* permit a form of broken polymorphism.
> 
Nonsense. This is a violation of an explicit precondition (that the
actual value associated with S be in the range of Sub_Integer).
-- 
Jeff Carter
Innovative Concepts, Inc.