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Thread: Instantiate a Class picked from a Class Array

  1. #1
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    Instantiate a Class picked from a Class Array

    I would like to change this:

    Code:
    obj = new _objectClass();
    into something like this:

    Code:
    var objClass:Class = _objectClassArray[range(0, _objectClassArray.length)] as Class;
    obj = new objClass();
    
    trace (_objectClassArray[range(0, _objectClassArray.length)]) // returns [class MyClip] or [class MyClip2] and so on..
    Actually this last piece of code throws the following error:

    TypeError: Error #1007: Instantiation attempted on a non-constructor.


    Full explanation:

    This code goes inside an ObjectPool from HYPE Framework of Joshua Davis.

    I´ve created a "MultipleObjectPool" and changed some little details , that is: the constructor, instead of receiving a Class as a parameter, receives then a Class Array, so each time it should create an object (via the request() function) of a Class that is picked randomically from the Class Array.

    Is that possible ?

    Thanks in advance!
    Last edited by ziriguidum; 03-05-2010 at 06:11 PM. Reason: add stuff, clarify

  2. #2
    Will moderate for beer
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    Are you sure that the objects in your class array are Classes? Does range return a single random integer in the specified range?

    If both of those are true, it should work.

    I suspect you have something other than classes in your array (such as String), causing objClass to be null.

  3. #3
    Mod cancerinform's Avatar
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    This example will give you the error you got, because Green is a string:

    var myArray:Array = new Array("Green");
    var objClass:Class = myArray[0] as Class;
    var objisplayObjectContainer = new objClass() as DisplayObjectContainer;
    addChild(obj);

    Changing the first line will correct the mistake:
    var myArray:Array = new Array(Green);

    Probably the array members are all strings.
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  4. #4
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    solved! now, how to decently extend a class?

    Hi, I solved it this way:

    obj = new _objectClassArray[range(0, _objectClassArray.length - 1)];

    simple

    I wonder now how could I extend the class ObjectPool
    Cause I've just copied the whole code into a new .as file I called "MultipleObjectPool" and changed very little stuff on it.
    But I know that's definitely not good practice.

    So, these are the changes I've made in the "MultipleObjectPool" class:

    1st - I added the "_objectClassArray" instance variable (not sure if it's called this way) , and removed the "_objectClass" instance variable since I didn't need it anymore.

    2nd - The constructor changed:

    Code:
    		public function ObjectPool(objectClass:Class, max:uint) {
    			_objectClass = objectClass;
    becomes

    Code:
    		public function ObjectPool(objectClassArray:Array, max:uint) {
    			_objectClassArray = objectClassArray;
    3rd - in function request():

    Code:
    obj = new _objectClass();
    becomes

    Code:
    obj = new _objectClassArray[range(0, _objectClassArray.length - 1)];
    I'm not good enough in OOP to know how to do this... so please help! Then I can share it with you!

    Thanks!

  5. #5
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    hey, thanks for answering,

    The objects in the array ware actually Classes.

    i 'm still don't know why this didn't work:

    Code:
    var objClass:Class = _objectClassArray[range(0, _objectClassArray.length)] as Class;
    obj = new objClass();
    but the important thing is that this works:

    Code:
    obj = new _objectClassArray[range(0, _objectClassArray.length - 1)];
    please read my previous post!

    thanks!

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