RE: [Dynapi-Dev] Inheritance

[Joachim L. <lu...@ho...>]

At 2000-12-12 14:01 , you wrote:
>> For example the ListItem class:
>> 
>>         function ListItem(text,value)
>>         {
>>             this.superClass = Label;
>>             this.superClass(text);
>>             this.value = value;
>>             ...
>>         }
>>         ListItem.prototype = new Label();
>> 
>> Perfect, except for the fact that one object is wasted to set the 
>> prototype.
>
>There's always the option of leaving out the last line if the extra
>object is a problem.

For me it's no problem, as long as I keep in mind the implications of it.

>It would only mean that if you made changes to Label.prototype at
>runtime, it wouldn't affect ListItem.prototype
>
>That could either be a good thing or a bad thing, depending what
>you want.

For me personally this would be a very bad thing...
I depend on the classes be subclassable to extend the functionality, among
other things.

>I'm not sure what the problem with the extra objects is, but you
>could make your extra objects identifiable by setting the ID:
>
>	ListItem.prototype = new Label('protoListItem');
>
>SD

The whole point I was trying to make is that the prototype is A Good Thing
(well...) and using object creators as constructors make the JavaScript
language in this way even more object-oriented.

It's true there is a (small) performance penalty but the added
functionality is well worth it in my opinion.

The biggest drawback IMHO with JS for now is the lack of
private/public/protected properties and methods. Instance variables can be
kludged however.
Even though the next revision of the language will have classes (finally!)
they can't be used in cross-browser environments.

/Lunna