Cobra: A simple JavaScript Class Library

Cobra is a simple JavaScript class library that attempts to provide a nice interface for creating classes and managing instances of those classes. It attempts to interfere as little as possible with how JavaScript usually behaves, meaning that it should work with any other JavaScript library.

Installing

From the directory you want to have the cobra source:

git clone http://github.com/jmtulloss/cobra.git
cd cobra
./compile
cp cobra.min.js <location cobra should be in your site directory>

Optionally, you can use the non-minified version of cobra.js available in src. The minified version is build using the Google Closure Compiler and is the version recommended for production environments.

How to Use the Library

Cobra.Class allows you to make very simple classes in a style modeled after python.

Everything is public. Indicate that you would prefer certain things be kept private with a leading underscore (IE. _privateMember)

All class methods are passed self as their first parameter. Self is guaranteed to be the instance of the class, whether this is the instance or not.

Provide a constructor called __init__ if you would like to initialize things.

Provide a base class in the __extends__ property if you want your class to inherit from that class.

Example

var Animal = new Cobra.Class({
    __init__: function(self) {
        self.breathes = true;
    }
});

var Feline = new Cobra.Class({
    __extends__: Animal,
    __init__: function(self) {
        Cobra.Class.ancestor(Feline, '__init__', self);
        self.claws = true;
        self.furry = true;
    },
    says: function(self) {
        console.log ('GRRRRR');
    }
});

var Cat = new Cobra.Class({
    __extends__: Feline,
    __init__: function(self) {
        Cobra.Class.ancestor(self, '__init__', self);
        self.weight = 'very little';
    },
    says: function(self) {
        console.log('MEOW');
    }
});

var Tiger = new Cobra.Class({
    __extends__: Feline,
    __init__: function(self) {
        Cobra.Class.ancestor(Tiger, '__init__', self);
        self.weight = 'quite a bit';
    }
});

Usage

>>> sneakers = new Cat();
Object breathes=true claws=true furry=true
>>> sneakers.breathes
true
>>> sneakers.claws
true
>>> sneakers.furry
true
>>> sneakers.weight
"very little"
>>> sneakers.says();
MEOW
>>> tigger = new Tiger()
Object breathes=true claws=true furry=true
>>> tigger.says()
GRRRRR

Tests

Cobra is tested with JSSpec, which you can find in the spec subfolder. Open spec_runner.html in your browser of choice to see all the tests passing.

Known to work in:

• Chrome
• Safari 4
• FireFox 3-3.5
• Internet Explorer 8
• node.js (Full test suite hasn't been run)

License

MIT License

Copyright (c) 2009-2010 Justin Tulloss

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.