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From: =?utf-8?Q?Yannick_Duch=C3=AAne_=28Hibou57?=
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 <yannick_duchene@yahoo.fr>
Newsgroups: comp.lang.ada
Subject: Re: Ada 2012: In-out parameters for functions
Date: Tue, 07 May 2013 06:13:08 +0200
Organization: Ada @ Home
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Xref: news.eternal-september.org comp.lang.ada:15396
Date: 2013-05-07T06:13:08+02:00
List-Id: <comp.lang.ada>

Le Tue, 07 May 2013 05:59:49 +0200, Yannick Duch=C3=AAne (Hibou57)  =

<yannick_duchene@yahoo.fr> a =C3=A9crit:
>
>      -- SPARK way to solve the issue
>      -- and to make explicit what it do.

To not count side effects, which are not even visible in any way at the =
 =

sub=E2=80=91program declaration, so not even declared out/in=E2=80=93out=
 to expect with  =

these. Except for SPARK (the same as above with an added side effect wit=
h  =

read/write involving a global variable):


     E : U; -- Side effect with this.

     procedure P
       (A :    out T;
        B : in out T;
        C : in     T);
     --# global E;
     --# derives
     --#    A from B, C, E &
     --#    B from B, C &
     --#    E from B;


Here, `E` appears at the declaration of `P` and is like declared in=E2=80=
=91out  =

(`A` derived from `E` means like if it was`in` and `E` derived from `B` =
 =

means like if it was also `out`).


-- =

=E2=80=9CSyntactic sugar causes cancer of the semi-colons.=E2=80=9D [1]
=E2=80=9CStructured Programming supports the law of the excluded muddle.=
=E2=80=9D [1]
[1]: Epigrams on Programming =E2=80=94 Alan J. =E2=80=94 P. Yale Univers=
ity