Question

I really get confused with these type of statements :

What does this mean :

1. when casting :

   var xyz = ClassA( obj as MovieClip );

2. when declaring/defining :

   var xyz:ClassA = new SomeOtherClass();

I mean, how 2 different classes are used in the same statements above ? Is this possible because of inheritance relationship ?

Thanks
V.

Answer 1

var xyz:ClassA = new SomeOtherClass()

xyz is declared as having the type ClassA, so this assignment will only work if SomeOtherClass is a subclass of ClassA. If not, an error will be thrown at compile time.

var xyz = ClassA( obj as MovieClip )

The result of this statement is a double cast: First, obj is cast to MovieClip, then to ClassA. If any of those two types is not in obj’s type hierarchy, the result is null.
Unless obj is not a MovieClip (in which case, trying to cast null to ClassA will cause a null pointer exception at runtime), there will not be an error, because you could assign anything to xyz – no variable type was specified.