From: "Alex R. Mosteo" <alejandro@mosteo.invalid>
Subject: Re: ANN: Ada industrial control widget library v1.0 released
Date: Thu, 17 Feb 2011 14:02:03 +0100
Date: 2011-02-17T14:02:03+01:00 [thread overview]
Message-ID: <ijj69n$bg$1@news.eternal-september.org> (raw)
In-Reply-To: e6n4nn5f2u3w$.21mjyezzj5f8$.dlg@40tude.net
Dmitry A. Kazakov wrote:
> On Wed, 16 Feb 2011 11:45:13 +0100, Alex R. Mosteo wrote:
>
>> (snip)
>
> I tried a bit by defining interfaces of drawable layers. I intentionally
> didn't make layer a GObject for this reason. But that was the easy part.
>
>> And I wonder how/if many access types would be needed.
>
> Lots, because GUI objects involved do not have their life times bound to a
> static scope. Objects are created and put into some container (e.g.
> widget) of class-wide instances. Ada cannot this without access types for
> many reasons. Similarly when an object is referenced, you need to be able
> to return it by-reference from a getter/setter function. By-reference
> result was ditched in Ada 2005 in favor of meaningless and useless
> limited-valued functions. There are other issues too, like dispatching on
> bare tags (generic dispatching constructor does not really work),
> immutable results (that is when you reference a limited element of an
> immutable container, the subtype of the result must be immutable. But when
> the container is mutable, the result is mutable too. C++ solves it by
> overloading, but I don't like that.)
Thanks, this is the kind of stuff that goes over my head, and where I can
really use other's knowledge. Instructive, even if it the subject is purely
hypothetical at this time.
Alex.
> I think it is possible to get rid of access types in GUI, if ARG
> considered this as a goal and changed the language accordingly. Nowhere in
> GUI objects are referenced without their containers and there is always a
> dedicate owner of each object.
next prev parent reply other threads:[~2011-02-17 13:02 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-02-12 14:22 ANN: Ada industrial control widget library v1.0 released Dmitry A. Kazakov
2011-02-14 15:34 ` Yannick Duchêne (Hibou57)
2011-02-14 17:06 ` Dmitry A. Kazakov
2011-02-15 10:02 ` Alex R. Mosteo
2011-02-15 11:00 ` Dmitry A. Kazakov
2011-02-16 10:45 ` Alex R. Mosteo
2011-02-16 13:57 ` Dmitry A. Kazakov
2011-02-17 13:02 ` Alex R. Mosteo [this message]
2011-02-15 15:56 ` Pascal Obry
2011-02-17 23:42 ` Rick
2011-02-18 9:41 ` Dmitry A. Kazakov
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