Overload [] operator in AS3

问题:

I just finished writing my own collecion class, and i'd really like to make it iterable with the for each or the simple for construct, or just to access elements with the collection[key] notation.

I've written a getElementAt(index):MyOwnElement function, but using it, is not as sexy as using the square brachets, don't even let me start on iterating..

Is there any way?

回答1:

You should take a look at mx.utils.Proxy -- subclassing your collection class from that (and setting it as dynamic) might give you access to some of the functionality you want (or at least something that's close enough.)

For example, here's an excerpt from the documentation of the nextValue() method:

"Allows enumeration of the proxied object's properties by index number to retrieve property values. However, you cannot enumerate the properties of the Proxy class themselves. This function supports implementing for...in and for each..in loops on the object to retrieve the desired values."

回答2:

There's a pretty good article on implementing the iterator pattern in AS3 here

回答3:

You can not override operator in AS3.
I think you may change 'getElementAt' to a short name likes 'at':) or assgin getElementAt to a temp variable....

回答4:

Depends on the internal structure of your collection. If your collection is stored as an Array then you can use properities to achieve a square bracket effect:

/*** MyCollection class ***/
private var elementHolder : Array;

public function get getElementAt() : Array{
   return elementHolder;
}
/*** Some other class******/
public function main() : void{
   trace("Element at 3: " + myCollection.getElementAt[3] );
}

If your collection is not stored in an array maybe you can convert it to an array (like the java Collection's toArray() method).

for example, if your collection is a linked list:

/*** MyCollection class ***/

public function get getElementAt() : Array{
   var temp : Array = new Array();
   while( node.next != null{
      temp.push( node );
   }
   return temp;
}
/*** Some other class******/
public function main() : void{
   trace("Element at 3: " + myCollection.getElementAt[3] );
}