ACTIONSCRIPT 3 Developer’s Guide en

ACTIONSCRIPT 3.0 DEVELOPER’S GUIDE
Working with arrays
public dynamic class TypedArray extends Array
{
private var dataType:Class;
public function TypedArray(typeParam:Class, ...args)
{
dataType = typeParam;
var n:uint = args.length
if (n == 1 && (args[0] is Number))
{
var dlen:Number = args[0];
var ulen:uint = dlen
if (ulen != dlen)
{
throw new RangeError("Array index is not a 32-bit unsigned integer ("+dlen+")")
}
length = ulen;
}
else
{
for (var i:int=0; i < n; i++)
{
// type check done in push()
this.push(args[i])
}
length = this.length;
}
}
}
TypedArray overridden methods
The TypedArray class overrides the four methods of the Array class that are capable of adding elements to an array. In
each case, the overridden method adds a type check that prevents the addition of elements that are not the correct data
type. Subsequently, each method calls the superclass version of itself.
The push() method iterates through the list of arguments with a for..in loop and does a type check on each
argument. Any argument that is not the correct type is removed from the args array with the splice() method. After
the for..in loop ends, the args array contains values only of type dataType. The superclass version of push() is then
called with the updated args array, as the following code shows:
AS3 override function push(...args):uint
{
for (var i:* in args)
{
if (!(args[i] is dataType))
{
args.splice(i,1);
}
}
return (super.push.apply(this, args));
}
The concat() method creates a temporary TypedArray named passArgs to store the arguments that pass the type
check. This allows the reuse of the type check code that exists in the push() method. A for..in loop iterates through
the args array, and calls push() on each argument. Because passArgs is typed as TypedArray, the TypedArray
version of push() is executed. The concat() method then calls its own superclass version, as the following code
shows:
Last updated 6/6/2012
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