Question

I’ve always found this interesting, and haven’t managed to fully understand it yet. Take this class:

package
{
    public class SomeClass
    {
        private var _myvar:String = "hello";

        public static function sayHello():void
        {
            trace(_myvar);
        }
    }
}

As we know, this will throw an error unless I declare _myvar as private static var _myvar

1120: Access of undefined property _myvar.

I don’t completely understand why _myvar isn’t in scope unless it’s static. Can anyone provide a easy to understand explanation of this?

Answer 1

As _myvar is not static it’s a property that is attached to an instance of SomeClass, i.e. it has only meaning each time you create a new SomeClass.

In contrary a static property is attached to the Class object, it exists only once and is not dependent of each instance of SomeClass created.

So when you try to reach _myvar from your static function sayHello it’s the same as calling this._myvar but you have only one static property and can have multiple instance created over the timelife of your application, what should be the value of this in that case ?