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From: =?utf-8?Q?Yannick_Duch=C3=AAne_=28Hibou57?=
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Newsgroups: comp.lang.ada
Subject: Re: Overring function and its returned type
Date: Fri, 09 Nov 2012 22:36:02 +0100
Organization: Ada @ Home
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Date: 2012-11-09T22:36:02+01:00
List-Id: <comp.lang.ada>

Le Fri, 09 Nov 2012 14:11:38 +0100, Dmitry A. Kazakov  =

<mailbox@dmitry-kazakov.de> a =C3=A9crit:
> A more general question is about overriding out-operations to narrower=

> subtypes, and/or overriding in-operations to wider subtypes. That coul=
d
> work.

Nice to read this. Made me think of it too, with the added rule that `in=
  =

out` would need to be fixed in overriding methods and not change their  =

type. However, about `out` mode, that may be more easy with function  =

returned object than with object =E2=80=9Creturned=E2=80=9D by an `out` =
parameter. An  =

`out` parameter may not be updated as a whole, which is required for  =

example to change the type of a discriminated type with default  =

discriminants. The function result case is safer because more predictive=
.  =

Or else, would have to require some `out` parameters to be updated as a =
 =

whole.

-- =

=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