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From: =?utf-8?Q?Yannick_Duch=C3=AAne_=28Hibou57?=
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Newsgroups: comp.lang.ada
Subject: Re: ANN: Ada 2005 Math Extensions, 20100810 release
Date: Fri, 13 Aug 2010 15:41:08 +0200
Organization: Ada At Home
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Date: 2010-08-13T15:41:08+02:00
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Le Fri, 13 Aug 2010 10:40:57 +0200, Dmitry A. Kazakov  =

<mailbox@dmitry-kazakov.de> a =C3=A9crit:
> Do you mean the use case or the offending code? I cannot say for the  =

> latter
> because I have no idea when it happens and if the code is legal [*]. T=
he
> simplest possible use case is the diamond diagram of generic packages =
 =

> [**]:
>
>   A
>  / \
> B  C
>  \ /
>   D
>
> In the specification of D you have to constrain B and C to the same A.=


This may also occurs if you wanna do some Mixins. This was how I came to=
  =

it the first if my mind is right.

> ** We were told how dreadful the diamond is, so bad that Ada may not  =

> allow
> to have MI, but for sacred generics anything is perfectly OK!
Did not understood this sentence, at least the last =E2=80=9Cbut for sac=
red  =

generics anything is perfectly OK!=E2=80=9D


-- =

There is even better than a pragma Assert: a SPARK --# check.
--# check C and WhoKnowWhat and YouKnowWho;
--# assert Ada;
--  i.e. forget about previous premises which leads to conclusion
--  and start with new conclusion as premise.