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Re: Ruby/Tk Some Basic Questions

David D'Andrea

11/11/2003 6:05:00 PM

If you'll forgive another newbie question:

What is an abstract class?

I think of classes as abstract already, and objects as concrete. Maybe
an abstract class is one that never gets instantiated, but is always
further specified / subclassed before being used?

David

On Monday, November 10, 2003, at 08:49 PM, Hidetoshi NAGAI wrote:

> Hi,
>
> From: "Zach Dennis" <zdennis@mktec.com>
>> I am wondering if there is a
>> major difference between TkRoot and TkWindow and it might be. In all
>> of the
>> ruby examples folks use TkRoot and assign all widgets to it, but the
>> TkWindow still exists. So why use one over the other?
>
> TkWindow class is an abstract class.
> --
> Hidetoshi NAGAI
> (nagai@ai.kyutech.ac.jp)
>


2 Answers

Lyle Johnson

11/11/2003 6:26:00 PM

0

David D'Andrea wrote:

> If you'll forgive another newbie question:
>
> What is an abstract class?
>
> I think of classes as abstract already, and objects as concrete. Maybe
> an abstract class is one that never gets instantiated, but is always
> further specified / subclassed before being used?

Yes, your guess is correct. Abstract base classes are never themselves
instantiated, but rather provide a set of basic functionality that their
(concrete) subclasses use.

Hidetoshi NAGAI

11/12/2003 2:27:00 AM

0