mixin.js

A small library to create powerful factories with useful mixins-based inheritence. Inspired by React.js's createClass factory method.

var MyLib.classFactory = mixin({

    getInitialStat: mixin.policy.method.MERGE_RESULT,

    render: mixin.policy.method.REQUIRED_ONCE,

    onStart: mixin.policy.method.DEFINE_MANY,

    updateComponent: mixin.policy.method.OVERRIDABLE

},{
    initialize: function () {

    },

});

This library is heavily inspired by the behavior of React's createClass method. This factory method has subtle complexity. mixins are able to be defined, and the mixins allow overriding of some methods, and special handling of others such as getInitialState() and propTypes.

Using the mixinjs library, we could create a factory method very similar to React's createClass method as shown below:

var mixin = require('mixin');

var React = {};

React.createClass = mixin({

    // this is provided by default
    //mixins: mixin.policy.method.DEFINE_MANY,

    // this is provided by default
    //statics: mixin.policy.method.DEFINE_MANY,

    propTypes: mixin.policy.object.MERGE,

    contextTypes: mixin.policy.object.MERGE,

    childContextTypes: mixin.policy.object.MERGE,

    getDefaultProps: mixin.policy.method.MERGE_RESULT,

    getInitialState: mixin.policy.method.MERGE_RESULT,

    getChildContext: mixin.policy.method.MERGE_RESULT,

    render: mixin.policy.method.REQUIRED_ONCE,

    componentWillMount: mixin.policy.method.DEFINE_MANY,

    componentDidMount: mixin.policy.method.DEFINE_MANY,

    componentWillReceiveProps: mixin.policy.method.DEFINE_MANY,

    shouldComponentUpdate: mixin.policy.method.REQUIRED_ONCE,

    componentWillUpdate: mixin.policy.method.DEFINE_MANY,

    componentDidUpdate: mixin.policy.method.DEFINE_MANY,

    componentWillUnmount: mixin.policy.method.DEFINE_MANY,

    updateComponent: mixin.policy.method.OVERRIDABLE

}, {
    initialize: function (props, context) {
        this.props = props;
        this.context = context;
        this.state = this.getInitialState();
    },

    isMounted: function () {

    },

    setProps: function (newProps, callback) {

    },

    replaceProps: function (newProps, callback) {

    }
});

Mixinjs has the following function signature:

var factory = mixin(policy [, baseImplementation]);

Policies

policy is an object with prop names and their corresponding policy declarations. The following policy declarations are available by default:

Policy | Behavior ------ | -------- mixin.policy.method.REQUIRED_ONCE | The corresponding method can only be implemented once. Multiple definitions will throw mixin.policy.method.DEFINE_MANY | The corresponding method can be defined as many times as you want. When calling the method, each definition will be invoked sequentially. mixin.policy.method.MERGE_RESULT | The corresponding method can be defined as many times as you want. It is expected that the method definitions return objects, and the results of each are merged together. mixin.policy.method.OVERRIDABLE | The corresponding method can be defined as many times as you want, but only the bottom-most definition will be used. mixin.policy.object.REQUIRED_ONCE | The corresponding property can only be defined once. Multiple definitions will throw. mixin.policy.object.MERGE | The corresponding property can be defined as many times as you want, and each definition will be merged together. mixin.policy.object.OVERRIDABLE | The corresponding property can be defined as many times as you want, but only the bottom-most definition will be used.

Add your own

You can add your own policy by making the following call:

mixin.addPolicy("MY_CUSTOM_POLICY", function (Constructor, propName, prop, classPolicy) {
    // do what you need to do here. Default behavior could be emulated as:
    Constructor.prototype[propName] = prop;
});

Default Policy Behaviors

By default, each class factory created using mixin has the following policy defined:

{
    /**
     * An array of Mixin objects to include when defining your class. Recursive.
     *
     * @type {array}
     * @optional
     */
    mixins: "MIXINS",

    /**
     * An object containing properties and methods that should be defined on
     * the class's constructor instead of its prototype (static methods).
     *
     * @type {object}
     * @optional
     */
    statics: "STATICS",

    /**
     * A function that can be used to initialize an instance
     *
     * @type {function}
     * @optional
     */
    initialize: mixin.policy.method.DEFINE_MANY,

    /**
     * Mainly for debugging purposes. This is the displayName applied to the constructor function.
     *
     * @type {String}
     * @optional
     */
    displayName: "CONSTRUCTOR_DISPLAY_NAME"
}

You can use an initialize method to any mixin or implementation and it will be used on instance initialization.