From jmc at r-project.org  Mon Nov 22 18:37:25 2010
From: jmc at r-project.org (John Chambers)
Date: Mon, 22 Nov 2010 09:37:25 -0800
Subject: [Rd] Ref classes: can I register fields as I register methods?
In-Reply-To: <005d01cb89ca$08f78770$1ae69650$@thyson@ku-eichstaett.de>
References: <005d01cb89ca$08f78770$1ae69650$@thyson@ku-eichstaett.de>
Message-ID: <4CEAAA55.4030906@r-project.org>

Well, it's an interesting idea, and the current implementation would fit 
with it.

One catch is that it goes against any obvious notion of checking for 
valid objects (admittedly, there are some difficulties in that already 
with active bindings being used).

Another issue is that in normal R programming practice, your "template" 
class would be in a package, in a namespace, and therefore locked. 
Conceptually at least, one would not be allowed to modify that definition.

Both these issues would be solved by using subclasses for the 
extensions, which seems more in the spirit of R.  Seems like you could 
hide the subclass details from your users if you wanted to.

So, something to think about, but the use case isn't convincing yet.

John

On 11/21/10 2:18 PM, Janko Thyson wrote:
> Hi there,
>
>
>
> is it possible to register fields as you can register methods with
> getRefClass("Classname")$methods(.)?
>
>
>
> I know that you should usually give some thought on which fields you need
> and hardcode them in the class def. But I'm playing around with dynamically
> creating/extending sort of a template class that already offers basic
> functionality shared by all objects that "inherit" from that class. If I
> follow the usual inheritance paradigm I would have to actually define those
> new "subclasses" and let them inherit from the superclass (contains
> argument(, right? But can I get around that by sort of registering new
> fields? Maybe with 'initFields(.)'?
>
>
>
> Thanks for any info on that,
>
> Janko
>
>
>
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[Rd] Ref classes: can I register fields as I register methods?
John Chambers