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From: Georg Bauhaus <rm-host.bauhaus@maps.arcor.de>
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Subject: Re: Seeking for papers about tagged types vs access to subprograms
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Date: 11 May 2013 11:49:12 GMT
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Date: 2013-05-11T13:49:12+02:00
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"Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de> wrote:

> The condition is moved to the post-condition. E.g.
> 
> # require X >= 0.0
>    function sqrt (X : Float) return Float;
> # ensure sqrt (X)**2 = X
> 
> is replaced with
> 
> # require true
>    function sqrt (X : Float) return Float;
> # ensure sqrt (X)**2 = X or else Constraint_Error raised

So sqrt tests X for being non-negative and raises C_E otherwise?
Can the test be turned off?

# require true
  procedure increase_pressure (P : in out Pot; X : Float);
# ensure pressure (P) = X * pressure (P'old) or else Kaboom raised

So where goes the precondition of the second kind mentioned
earlier, for calls, the one that is needed for correctness of the program?
I take it that the former kind of precondition prevents Kaboom in the
system?