Cloning arrays
Flash Player 9 and later, Adobe AIR 1.0 and
later
|
The Array class has no built-in method for
making copies of arrays. You can create a
shallow
copy
of
an array by calling either the
concat()
or
slice()
methods with
no arguments. In a shallow copy, if the original array has elements
that are objects, only the references to the objects are copied
rather than the objects themselves. The copy points to the same
objects as the original does. Any changes made to the objects are
reflected in both arrays.
In a
deep copy
,
any objects found in the original array are also copied so that
the new array does not point to the same objects as does the original
array. Deep copying requires more than one line of code, which usually
calls for the creation of a function. Such a function could be created
as a global utility function or as a method of an Array subclass.
The following
example defines a function named
clone()
that does
deep copying. The algorithm is borrowed from a common Java programming technique.
The function creates a deep copy by serializing the array into an instance
of the ByteArray class, and then reading the array back into a new
array. This function accepts an object so that it can be used with
both indexed arrays and associative arrays, as shown in the following
code:
import flash.utils.ByteArray;
function clone(source:Object):*
{
var myBA:ByteArray = new ByteArray();
myBA.writeObject(source);
myBA.position = 0;
return(myBA.readObject());
}
|
|
|
