The base Class object

Quintus uses the Simple JavaScript inheritance Class object, created by John Resig and described on his blog:

http://ejohn.org/blog/simple-javascript-inheritance/

The class is used wholesale, with the only differences being that instead of appearing in a top-level namespace, the Class object is available as Q.Class and a second argument on the extend method allows for adding class level methods and the class name is passed in a parameter for introspection purposes.

Classes can be created by calling Q.Class.extend(name,{ .. }), although most of the time you'll want to use one of the derivitive classes, Q.Evented or Q.GameObject which have a little bit of functionality built-in. Q.Evented adds event binding and triggering support and Q.GameObject adds support for components and a destroy method.

The main things Q.Class get you are easy inheritance, a constructor method called init(), dynamic addition of a this._super method when a method is overloaded (be careful with this as it adds some overhead to method calls.) Calls to instanceof also all work as you'd hope.

By convention, classes should be added onto to the Q object and capitalized, so if you wanted to create a new class for your game, you'd write:

Q.Class.extend("MyClass",{ ... });

Examples:

Q.Class.extend("Bird",{ 
  init: function(name) { this.name = name; },
  speak: function() { console.log(this.name); },
  fly: function()   { console.log("Flying"); }
});

Q.Bird.extend("Penguin",{
  speak: function() { console.log(this.name + " the penguin"); },
  fly: function()   { console.log("Can't fly, sorry..."); }
});

var randomBird = new Q.Bird("Frank"),
    pengy      = new Q.Penguin("Pengy");

randomBird.fly(); // Logs "Flying"
pengy.fly();      // Logs "Can't fly,sorry..."

randomBird.speak(); // Logs "Frank"
pengy.speak();      // Logs "Pengy the penguin"

console.log(randomBird instanceof Q.Bird);    // true 
console.log(randomBird instanceof Q.Penguin); // false
console.log(pengy instanceof Q.Bird);         // true 
console.log(pengy instanceof Q.Penguin);      // true 

Simple JavaScript Inheritance By John Resig http://ejohn.org/ MIT Licensed.

Inspired by base2 and Prototype