Class.md

nbd/Class

The heart of nbd.js's flexibility and power comes from the class Class. Class provides the base functionality from which two main modes of inheritance are possible: linear (classical), and horizontal (trait).

.extend(prototype, static) Linear Inheritance

This is the inheritance everybody is familiar with. In JavaScript, linear inheritance is achieved through the lookup behavior of objects and their prototypes. Class provides the function Class.extend() which will set up the inheritance chain properly.

require(['nbd/Class'], function(Class) {
  var Subclass = Class.extend({
    // prototype properties here
    foo: 'bar'
  }, {
    // static properties here
    foo: 'baz'
  }),

  instance = new Subclass();

  instance.foo; // 'bar'
  Subclass.foo; // 'baz'
});

returns Function The new class that was created

.mixin(...traits) Horizontal Inheritance

Horizontal inheritance is a newer form of inheritance that allows code reuse by sharing a common trait. nbd.js achieves this through the .mixin() function that all descendants of Class have. Note: Class itself does not have .mixin()

You can .mixin() any object into any descendant of Class, and all instances of that class will have access to the mixed-in object's own properties.

require(['nbd/Class'], function(Class) {
  var badTrait = {
    corrupt: function() {
      this.foo = 'bad';
    }
  },

  Subclass = Class.extend({
    foo: 'bar'
  }, {
    foo: 'baz'
  }),

  instance = new Subclass();

  Subclass.mixin(badTrait);

  instance.corrupt();
  instance.foo; // 'bad' corrupted!
  Subclass.foo; // 'baz' static properties unaffected
});

The primary purpose of horizontal inheritance is to be able to add functionality at any time regardless of inheritance structure. For example, Model uses .mixin() to mix in the nbd/trait/pubsub trait in order to gain the ability to bind and trigger events.

returns Function The class .mixin() was called on.