View source for Constructors and prototypes


The Javascript language does not have classes, it supports only objects. However, a common behavior of objects can be implemented using prototypes.

===Adding class properties and methods===

Even if objects are not class members they can share a set of common properties and methods.

Currently Yate does not automatically provide a prototype for objects. This can be added easily to a constructor:

<pre>
function MyConstructor()
{
    this.MyProperty = 0;
}

MyConstructor.prototype = new Object;
</pre>

Now shared properties and methods can be added to the prototype:

<pre>
MyConstructor.prototype.SharedProperty = 1;

MyConstructor.prototype.MyMethod = function(x)
{
    return x + this.MyProperty;
};
</pre>
'''IMPORTANT:''' There's a semicolon after the closing brace as this is an assignment and not a function declaration

===Accessing the prototype===

Javascript does not provide a standard way of accessing an object's prototype.

Yate uses a widespread extension of a '''__proto__''' attribute to access the prototype:

<pre>
    Engine.print_r(this.__proto__);
</pre>

'''See also'''
* [[Javascript]]

'''External links'''
* [http://www.2ality.com/2010/12/javascripts-prototypal-inheritance.html An easy way to understand JavaScript’s prototypal inheritance]
* [http://joost.zeekat.nl/constructors-considered-mildly-confusing.html Constructors considered mildly confusing]

[[Category:Javascript]] [[Category:Programmers]]