From: "Paweł 'Nivertius' Płazieński" <nivertius@gmail.com>
Subject: Re: Access to function returning class-wide type
Date: Thu, 21 Aug 2008 13:56:35 +0200
Date: 2008-08-21T13:56:35+02:00 [thread overview]
Message-ID: <g8jl5o$oj8$1@registered.motzarella.org> (raw)
In-Reply-To: o2pfrvcvityp.gy34yp0t1m5l$.dlg@40tude.net
Dmitry A. Kazakov wrote:
>> What I need is a access type to 'constructor' of an derivate of abstract
>> object.
>> As I presented, there is a workaround, but that's not the 'right' way to
>> do it. I really want to do it without some tricky wrapping.
>> How do I define The_Access_Type to do what I want?
> See Ada.Tags.Generic_Dispatching_Constructor. It gives you a function
> constructing an object from the type tag, the parameters (Natural in your
> case) using the function you want (Proc). It goes as follows:
>
> with Ada.Tags.Generic_Dispatching_Constructor;
> package A is
> type Abstracted is abstract tagged null record;
> function Proc (N : not null access Natural)
> return Abstracted is abstract;
> function Constructor is
> new Ada.Tags.Generic_Dispatching_Constructor
> (Abstracted, Natural, Proc);
> end A;
I belive that would work too, but at the cost of defining function Proc (N :
not null access Natural) return ... for each descendant type. That would be
another wrapper, so it's the same resolution to the problem as Proc_Wrapper
in my original code, assuming that I need Proc (N : Natural) as well.
Tell me that I'm wrong, please ;-)
--
Paweł Płazieński aka Nivertius
"In the end, there will be Ada, XML and gzip"
next prev parent reply other threads:[~2008-08-21 11:56 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-08-21 10:13 Access to function returning class-wide type Paweł 'Nivertius' Płazieński
2008-08-21 10:33 ` Paweł 'Nivertius' Płazieński
2008-08-21 11:02 ` Dmitry A. Kazakov
2008-08-21 11:56 ` Paweł 'Nivertius' Płazieński [this message]
2008-08-21 13:34 ` Dmitry A. Kazakov
2008-08-22 4:53 ` Randy Brukardt
2008-08-22 23:50 ` Randy Brukardt
2008-08-21 12:01 ` Georg Bauhaus
2008-08-21 13:01 ` Paweł 'Nivertius' Płazieński
2008-08-21 13:50 ` Dmitry A. Kazakov
2008-08-21 19:30 ` Paweł 'Nivertius' Płazieński
2008-08-21 20:56 ` Dmitry A. Kazakov
2008-08-22 7:34 ` Paweł 'Nivertius' Płazieński
2008-08-21 17:02 ` Adam Beneschan
2008-08-21 19:22 ` Paweł 'Nivertius' Płazieński
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