12.4. Adding Custom Methods to an Object Instance
Problem
You want to add custom methods to an object.
Solution
Assign a function definition (or a reference to one) to a custom property of an object that is already instantiated.
Discussion
You can add functionality to objects (instances of a class) by assigning new methods to them. First, define a function. Then store a reference to the function in a custom property of the object. That is, the definitions of an object’s methods are stored as properties of the same object.
This example stores a function in the custom property
methodProp
:
myObject = new Object( ); myObject.methodProp = function ( ) { trace("Hello World"); };
The preceding example assigns a method to an object
using
an anonymous function
. However, you can also use
object properties to store references to named
functions
. The following example stores a reference to the
named function, myMethodFunction( )
, in the
property myMethod
:
// Define a named function.
function myMethodFunction ( ) {
trace(this.myProperty);
}
// Create a new object. You can assign custom methods to any kind of object (movie
// clip, array, etc.), but this example uses a generic object of the Object
class. myObject = new Object( ); // Create a custom property on the object. This is not necessary, per se, but we use // it here to illustrate that when a function is called as a method of an object, the // function has access to all the properties of that object by means of // self-references (using the ...
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