heterarchy

Cooperative multiple inheritance for CoffeeScript, à-la Python.

Adds multiple inheritance support to CoffeeScript (and JavaScript). It uses the C3 linearization algorithm as described in the famous Dylan paper.

Example

The library handles multiple inheritance and chains calls to super in a linear order, solving the diamond problem and allowing for cooperative methods. For example, the following class heterarchy:

Can be implemented with the following code.

{multi} = require 'heterarchy'

class A
method: -> "A"

class B extends A
method: -> "B > #{super}"

class C extends A
method: -> "C > #{super}"

class D extends multi B, C
method: -> "D > #{super}"

Calling method on a D instance would return the string D > B > C > A showing the class linearization.

Documentation

API

• heterarchy
  GitHub: heterarchy.litcoffee

Tests

• spec.heterarchy
  GitHub: heterarchy.spec.coffee

Installation

This is a standard Node.JS module. One may install the library with:

npm install heterarchy

Usage in the browser

After cloning or downloading the repository you can build all necessary files with

make

This will create heterarchy.js in the lib/ folder. Including that file in the browser will result in a global heterarchy variable that contains the normally exported functions.

Since the library requires underscorejs you must include it before heterarchy. The functions that are used from underscorejs are (in case you don’t need the entire library):

head, tail, map, find, some, without, isEmpty,
every, memoize, reject, isEqual, reduce

Example

<script type="text/javascript" src="path/to/underscore.js"></script>
<script type="text/javascript" src="path/to/browser.heterarchy.js"></script>
<script type="text/javascript" src="my_app.coffee"></script>

where my_app.coffee could be

class A
method: -> "A"

class B extends A
method: -> "B > #{super}"

class C extends A
method: -> "C > #{super}"

# note the heterarchy namespace
class D extends heterarchy.multi B, C
method: -> "D > #{super}"

Contributors

This library is maintained by Juanpe Bolivar, with the help of these outstanding contributors:

• Jim Neuedorf @jneuendorf

Added support for class methods, global exports in the browser and fixed various issues.

License

Heterarchy is Free Software and is distributed under the MIT license (see LICENSE).

Copyright (c) 2013, 2015 Juan Pedro Bolivar Puente raskolnikov@gnu.org

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.