What is the use in having the valueOf() function? - actionscript-3

Question

Why is the valueOf() function present in everything in AS3? I can't think of an instance when this isn't redundant. In terms of getting a value, x and x.valueOf() are completely the same to me (except that one probably takes more CPU cycles). Furthermore even though they may not be the same in terms of setting something, x.valueOf() = y (if even legal) is just completely pointless.
I am confident though that this is here for a reason that I'm just not seeing. What is it? I did try Googling for a minute. Thanks!

Answer 1

As you say, its completely redundant.
The valueOf method is simply included so that ActionScript 3 complies with the ECMA language specification (obviously there are other requirements to be an ECMA language - i believe toString is another example).

Answer 2

Returns the primitive value of the specified object. If this object does not have a
primitive value, the object itself is returned.
Source: Adobe AS3 Reference http://help.adobe.com/en_US/FlashPlatform/reference/actionscript/3/Object.html#valueOf()
Edit:
A primitive value can be a Number, int, bool, etc... They are just the value. An object can have properties, methods, etc.
Biggest difference, in my opinion though:
primitive2 = primitive1;
In this example, primitive 2 contains a copy of the data in primitive 1.
obj2 = obj1;
In this one, however, ob2 points to the same object as obj1. Modify either obj1 or obj2 and they both reflect the change, since they are references.
In short, valueOf is used when you want to see the primitive representation of an object (if one exists) rather than the object itself.

Answer 3

Here is a clear example between
Value Vs. ValueOf:
Value = Thu Jan 2 13:46:51 GMT-0800 2014 (value is date formatted)
ValueOf = 1388699211000 (valueOf is in Raw epoch)

Answer 4

valueOf isn't useless. It allows an Object to provide a value for an expression that expects a primitive type. It's available in AS3 as well as JavaScript.
If someone wrote a function that takes an int, you could pass it your object (more precisely, it passes the result of your object's valueOf() function).
The usefulness is tempered by 1) the fact that the Object isn't passed, so it's only an Object in the outermost scope, and 2) the fact that it's a read-only operation, no assignment can be made.
Here're a couple concrete examples off the top of my head:
Example 1: A Counter class that automatically increments its value every time it's read:
class Counter
{
private var _cnt:int = 0;
public function Counter() { }
public function valueOf():int
{
return _cnt++;
}
public function toString():String { return ""+valueOf(); }
}
Usage:
var c:* = new Counter();
trace(c); // 0
trace(c); // 1
trace(2*c+c); // 2*2+3 = 7
trace(c); // 4
Notes:
I added the toString() pass-through, since functions that take String prefer toString over valueOf.
You must type c as * and not Counter, otherwise you'll get a compiler error about implicit coercion of Counter to Number.
Example 2: A (read only) pointer type
Let's say you have an array of ints, and you want to have a reference (aka pointer) to an element in the array. ECMA scripts don't have pointers, but you can emulate one with valueOf():
class ArrayIntPointer
{
private var arr:Array;
private var idx:int;
public function ArrayIntPointer(arr:Array,
idx:int)
{
this.arr = arr;
this.idx = idx;
}
public function valueOf():int
{
return arr[idx];
}
public function toString():String { return ""+valueOf(); }
}
Usage:
var arr:Array = [1, 2, 3, 4, 5];
var int_ptr:* = new ArrayIntPointer(arr, 2);
// int_ptr is a pointer to the third item in the array and
// can be used in place of an int thanks to valueOf()
trace(int_ptr); // 3
var val:int = 2*int_ptr+1;
trace(val); // 7
// but it's still an object with references, so I
// can change the underlying Array, nand now my
// object's primitive (aka, non-Object types) value
// is 50, and it still can be used in place of an int.
arr[2] = 50;
trace(int_ptr); // 50
// you can assign int_ptr, but sadly, this doesn't
// affect the array.
That's pretty slick. It'd be really slick if you could assign the pointer and affect the array, but unfortunately that's not possible, as it assigns the int_ptr variable instead. That's why I call it a read-only pointer.