well this is so that you can create a interface say List
have an abstract class AbstractList implement the common methods
and then say VectorList extends AbstractList which implements all the
methods
but the user cannot instantiate a Abstract class object
so although he can now do
var t:VectorList = new VectorList();
var t:AbstractList = new AbstractList (); will throw an error so the
developer will know not to use this class by itself
On 6/27/07, Roman Protsiuk <[EMAIL PROTECTED]> wrote:
Though I don't understand why do you need this kind of behavior
(throwing exception in constructor the way you do it) there's been quite a
discussion about abstract classes in AS3.
In flexcoders archives, you can find a lot of info and links to resources
devoted to this subject.
For not to go by without my 2 cents: as I see it in most situations all
you need is interface to implement by your class. It's more flexible than an
abstract class.
R.
On 6/28/07, Firdosh Tangri <[EMAIL PROTECTED]> wrote:
>
> cool thanks guys ....I was trying a good way to figure out how to go
> about abstract classes
>
> so if the class is abstract I would do
>
> public function AbstractList(){
> throw new Error("Abstract class cannot be instantiated");
> }
>
> public function List(){
> //what I need to
> try{
> super();
> }
> catch(err:Error){}
> }
>
> this seems to work fine
>
> if anyone has a better suggestion I am all ears :)
>
> cheers
> firdosh
>
>
> On 6/27/07, reflexactions < [EMAIL PROTECTED]> wrote:
> >
> > 'cos in every class unless you make an explicit call to super there
> > is an automatic implicit call to super() before anything else
> > executes in the subclass constructor.
> >
> > The explicit call to super can include params as in super(x) if the
> > superclass has such a constructor.
> >
> > One gotcha is if you extend a class that has a constructor that takes
> > an argument and decide not to override the constructor then you
> > extend that class you cant call super with an argument anymore ie
> >
> > public class classA{
> > function classA(xx:int){}
> >
> > ...other stuff...
> > }
> >
> > public class classB extends classA{
> > ...only other stuff is overridden...
> > }
> >
> > public class classC extends classB{
> > function classC(xx:int){
> > super(xx);//compile error.... no such constructor in classB
> > ..do some stuff..
> > }
> > }
> >
> > --- In [email protected]<flexcomponents%40yahoogroups.com>,
> > "Firdosh Tangri" <[EMAIL PROTECTED]>
> >
> > wrote:
> > >
> > > hey guys
> > > I have a class
> > >
> > > public class ClassA{
> > >
> > > public function ClassA(){
> > > trace("classA constructor");
> > > }
> > >
> > > }
> > >
> > > ===========================================================
> > >
> > > public class ClassB extends ClassA{
> > >
> > > public function ClassB (){
> > > trace("classB constructor");
> > > }
> > >
> > > }
> > >
> > > ===================================================================
> > >
> > >
> > > when I do
> > >
> > > var c:ClassB = new ClassB();
> > >
> > >
> > > why do both the statements get traced out even though I am not
> > calling super
> > >
> > > cheers
> > > firdosh
> > >
> >
> >
>
