uberproto

JavaScript object inheritance sugar: Easy extension, mixins, super methods, proxies

npm install uberproto
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Uberproto

Uberproto is a simple base object that adds some sugar to ECMAScript 5 style object inheritance in JavaScript.

Here is what it can do in a nutshell:

  • Easily extend objects
  • Initialization methods
  • Super methods
  • Mixins
  • Method proxies

With a small footprint (about 1Kb minified) and an easy to handle API of just four methods it also doesn't add a lot of baggage to your JavaScript application.

Usage

UberProto can be used as a CommonJS AMD module (e.g. with RequireJS), NodeJS or directly in the browser. If no module loader is available, the global variable Proto will be defined after you include the script. In the browser you have two options: The default build that includes EcmaScript 5 shims or, if you only support modern browsers or provide the shims already, without.

Using AMD (e.g. RequireJS)

Make sure proto.js is in the right folder and then just define a module like this:

define(['proto'], function(Proto) {
    // Source goes here
});

In the browser

Download proto.min.js or the EcmaScript 5 version proto.es5.min.js. You can also bower install uberproto if you are using Bower as your package manager. Then simply include the file as a script:

<script type="text/javascript" src="proto.min.js"></script>

Now Proto is available as a global vairable.

With NodeJS

After installing the package using NPM

npm install uberproto

just require it like any other module:

var Proto = require('uberproto');

Creating objects

Extend

You can extend any UberProto object by using extend to create a new object that inherits from the current one. Internally Object.create is being used (the library provides a polyfill for browsers that don't support Object.create) and the prototype is set to the object that you are extending. If defined, the init method will be used as the constructor. That way you can define a simple Person object (which will be reused throughout the next paragraphs):

var Person = Proto.extend({
    init : function(name) {
        this.name = name;
    },

    fullName : function() {
        return this.name;
    }
});

You can also define a plain object and pass it to UberProto object methods:

var PersonObject = {
    init : function(name) {
        this.name = name;
    },

    fullName : function() {
        return this.name;
    }
};

Play around with the examples in this JSFiddle.

Initialize

You can create a new instance by calling create. This will create a new object and call the init method, if defined:

var dave = Person.create('Dave');
console.log(dave.name); // -> 'Dave'
console.log(dave.fullName()); // -> 'Dave'

If you are using init already for something else you can also set the __init property to the method name of your intialization method:

var MyPerson = Proto.extend({
    __init : 'construct',

    construct : function(name) {
        this.name = name;
    }
});

For calling the constructor on a plain object, call create on an UberProto object:

var john = Proto.create.call(PersonObject, 'John');
console.log(john.fullName()); // -> 'John'

Overwriting create is great if you want to customize the way new objects are being instantiated.

Super methods

In each method this._super refers to the method being overwritten, if there is one. For our Person object, for example, it would be a lot better if it also had a last name:

var BetterPerson = Person.extend({
    init : function(name, lastname) {
        // If you want to pass all original arguments to the
        // _super method just use apply:
        // this._super.apply(this, arguments);        
        this._super(name);
        this.lastname = lastname;
    },

    fullName : function() {
        return this._super() + ' ' + this.lastname;
    }
});

var dave = BetterPerson.create('Dave', 'Doe');
console.log(dave.name); // -> 'Dave'
console.log(dave.lastname); // -> 'Doe'
console.log(dave.fullName()); // -> 'Dave Doe'

You can also extend a plain object if you don't want to inherit from an UberProto object:

var BetterPersonObject = Proto.extend({
    init : function(name, lastname) {
        this._super(name);
        this.lastname = lastname;
    },

    fullName : function() {
        return this._super() + ' ' + this.lastname;
    }
}, PersonObject); // Pass the plain object as the second parameter

Mixins

Mixins add functionality to an existing object. Mixins can also access their super methods using this._super. This will either refer the overwritten method on the object itself or the one on the prototype:

Person.mixin({
    init : function()
    {
        this._super.apply(this, arguments);
        this.can_sing = true;
    },

    sing : function()
    {
        return 'Laaaa';
    }
});

var dude = Person.create('Dude');
console.log(dude.sing()); // -> 'Laaaa'
console.log(dude.can_sing); // -> true

Actual instances can be mixed in just the same:

var operaSinger = Person.create('Pavarotti');
operaSinger.mixin({
    sing : function()
    {
        return this._super() + ' Laalaaa!';
    }
});

console.log(operaSinger.sing()); // -> 'Laaaa Laalaaa!'

And you can also mix into plain objects e.g. overwriting the constructor of PersonObject:

Proto.mixin({
    fullName : function() {
        return 'My name is: ' + this._super();
    }
}, PersonObject);

// Create a plain object without calling the constructor
var instance = Object.create(PersonObject);
instance.name = 'Dude';
console.log(instance.fullName()); // 'My name is: Dude'

Method proxy

You can create proxy callbacks, that make sure that this will always point to the right object:

var callback = operaSinger.proxy('fullName');
console.log(callback()); // -> 'Pavarotti'

And you can partially apply function arguments:

operaSinger.mixin({
    sing : function(text)
    {
        return this._super() + ' ' + text;
    }
});

var singHello = operaSinger.proxy('sing', 'Helloooooo!');

singHello() // Laaaa Laalaaa! Helloooooo!

proxy only works on objects extended from UberProto.

Changelog

1.1.1

  • Updating component and bower (#6)
  • Only wrap functions that are actually calling ._super (#7)
  • Improved build and tests

1.1.0

  • Extract ES5 shims (build shim-less version)
  • Use Function.bind for proxy
  • Switched test suite to Mocha
  • GruntJS build
  • Bower component: bower install uberproto

1.0.3

  • Added Object.getPrototypeOf shim
  • Updated documentation
  • Added Travis CI

1.0.2

  • Added __init property to allow constructor functions to be named other than init. Fixes issue #1

1.0.1

  • API now usable with plain objects like Proto.mixin({}, PlainObject)

1.0.0

  • Initial stable release

License

Copyright (C) 2013 David Luecke daff@neyeon.com

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

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