Class.js

High performance classical inheritance for node.js.

Installation

Install the Kiwi package manager for nodejs and run:

  $ kiwi -v install class

via npm:

$ npm install class

About Class.js

Without wasting performance on cross-browser functionality, class.js is an extremely light (20-ish SLOC) class implementation.

By utilizing idiomatic prototypal inheritance techniques this implementation is very fast. There are no wrapping or super hacks involved.

Features

• Fast
• Tiny
• Mixin support with included() hook
• Subclassing support with extended() hook

Examples

var Class = require('class').Class
var User = new Class({
  extend: {
    extended: function(subclass){
      // called when User.extend() is called,
      // in this case passes Admin
    }
  },
  constructor: function(name){
    this.name = name
  },
  toString: function(){
    return '[User ' + this.name + ']'
  }
})
var Admin = User.extend({
  constructor: function(name) {
    User.call(this, name.toUpperCase())
  }
})
var SomeMixin = new Class({
  extend: {
    included: function(superclass){
      // called when Admin.include()
      // is called, in this case Admin
      // will become the contents of "superclass"
    }
  },
  foo: 'bar'
})
Admin.include(SomeMixin)
puts(new Admin('tj'))
// => "[User TJ]"

Benchmarks

Currently the benchmarks compare regular prototypal inheritance, node's sys.inherits(), and class.js. Each subclasses User as Admin, and creates an instance 500,000 times.

λ  class.js: node benchmark.js
running 500000 times
prototype : 68 ms
sys.inherits() : 1512 ms
class.js : 2510 ms

Running Tests

Specs are written using JSpec, however no additional installations are required as JSpec is froozen to spec/lib, just simply run:

$ make test

License

(The MIT License)

Copyright (c) 2009 TJ Holowaychuk <tj@vision-media.ca>

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.