Hi Adrian,
Your i:Object declaration is a _compile-time_ declaration. All it's
there for is to make the compiler happy. instanceof, which is what I'm
using (typeof is an older construct which is more limited and less
safe) is an operator which does a comparison at runtime on the
underlying object that you're passing around. Rather than at compile
time. So it doesn't know or care whether you typed i:Object or
i:String - it's just working with the actual value of i, which has an
underlying type.
This code works because a number is represented by a Number class,
which is a subclass of Object - and because a string is represented by
a String class, which is also a subclass of Object. (This isn't quite
true, but is true enough for these circumstances!). Because Object is
the common superclass, the compiler doesn't get upset when you type
myFunction(5) or myFunction("fred").
It's somewhat clearer if I show you an example of a class (rather than
Number or String - they are both a little bit different internally but
Flash hides the differences from us using something called
autoboxing):
class A {
function A(){}
}
class B extends A{
function B(){}
}
var a:A=new A();
var b:B=new B();
var c:A=new B();
trace(a instanceof A); //true
trace(b instanceof A); //true
trace(c instanceof A); //true
trace(a instanceof B); //false
trace(b instanceof B); //true
trace(c instanceof B); //true
As you can probably see, instanceof is working on the underlying
object that's been created, never mind what you typed after the colon.
The reason I use instanceof instead of typeof is that typeof would
give you a less useful answer:
trace(typeof A); // "function" (because it's a constructor function)
trace(typeof B); // "function" (because it's a constructor function)
In your case, typeof should do the job. But just bear in mind that
it's an old operator, and should probably be retired. ;-)
HTH,
Ian
On 6/15/06, Adrian Park <[EMAIL PROTECTED]> wrote:
Ian, I'm intrigued if your suggestion works - I had considered it but
assumed it wouldn't work because the result of the typeOf operation would
just be 'object' (since that is what the parameter is typed as).
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