classy

Classy - Classes for JavaScript

Classy offers the ability to easily define classes, call super or overriden methods, define static properties, and mixin objects in a very flexible way.

Meant to be used in the browser and in node.js as well.

Use dist/classy.js

    var Vehicle = classy.define({
        alias: 'vehicle',

        init: function(year){
            this.year = year
        }
    })

    var Car = classy.define({
        extend: 'vehicle'
        //or extend: Vechicle
        alias: 'car',

        init: function(year, make){
            this.callSuper()
            this.make = make
        },

        getName: function(){
            return this.make
        }
    })

    var ford = new Car(1980, 'Ford')
    console.log(ford.year)
    console.log(ford.make)

Notice the callSuper() method call, which can be used in any class method, and will call the method with the same name found on the super class. It also automatically transmits all the arguments it has, so you don't have to manually do so.

ford.getName() === 'Ford' //is true

    classy.override('car', {
        getName: function(){
            return this.callOverriden() + ', made in ' + this.year
        }
    })
    //now
    ford.getName() === 'Ford, made in 1980' //is true

You can use the class alias in order to easily reference which class you want to extend or override. This also helps you get a reference to your class by

    var Car = classy.getClass('car')
    var Vehicle = classy.getClass('vehicle')

init as constructor

Use the init method as the constructor

Example

    var Animal = classy.define({

        //when a new Animal is created, the init method is called
        init: function(config){
            config = config || {}

            //we simply copy all the keys onto this
            Object.keys(config).forEach(function(key){
                this[key] = config[key]
            }, this)
        }
        })

    var Cat = classy.define({
        extend: Animal,
        alias: 'cat',

        init: function(){
            this.callSuper()
            this.sound = 'meow'
        },

        getName: function(){
            return this.name
        }
    })

    var lizzy = new Cat({ name: 'lizzy' })

callSuper and callOverriden

Use the callSuper and callOverriden methods to call the super and overriden methods. You don't have to worry about forwarding the arguments, since this is handled automagically for you.

If there is no super or overriden method with the same name you don't have to worry either, since callSuper and callOverriden won't break. they will simply and silently do nothing

Example

    //create a shape class
    classy.define({
        alias: 'shape',

        getDescription: function(){
            return this.name
        }
    })

    //create a rectangle class with a width and a height
    classy.define({
        extend: 'shape',
        alias: 'rectangle',

        name: 'rectangle',
        init: function(size){
            this.width = size.width
            this.height = size.height
        },

        getArea: function(){
            return this.width * this.height
        },

        setHeight: function(h){ this.height = h },
        setWidth: function(w){ this.width = w }
    })

    classy.override('rectangle', {
        getDescription: function(){
            //reimplement the getDescription, but use the overriden implementation as well
            return 'this is a ' + this.callOverriden()
        }
    })

    //create a square class
    classy.define({
        extend: 'rectangle',
        alias: 'square',

        init: function(size){
            if (size * 1 == size){
                //the size is a number
                size = { width: size, height: size}
            } else {
                size.width = size.height
            }

            this.callSuper()
        },

        setHeight: function(h){
           //callSuper will automatically pass the arguments to Rectangle.setHeight, so h will be forwarded
           this.callSuper()  //or you could use this.callSuperWith(10) if you want to manually pass parameters
           this.setWidth(h)
        }
    })

You can also use callSuperWith and callOverridenWith to manually pass all parameters

Example

    //...
    setHeight: function(h){
        this.callSuperWith(h*2)
    }
    //...

Static properties and $ownClass

You can easily define static properties for classes.

    var Widget = classy.define({

        statics: {

            idSeed: 0,

            getDescription: function(){
                return 'A Widget class'
            },

            getNextId: function(){
                return this.idSeed++
            }
        },

        init: function(){
            this.id = this.$ownClass.getNextId()
        }
    })

    Widget.getDescription() == 'A Widget class' // === true

    var w = new Widget()
    w.id === 0

    w = new Widget()
    w.id === 1

On every instance, you can use the $ownClass property in order to get a reference to the class that created the instance.