JavaScript dependency injection - sort of...

di.js

/**
 * Dependency Injection
 * Copyright (c) 2014, marlun78
 * MIT License, https://gist.github.com/marlun78/bd0800cf5e8053ba9f83
 *
 * === EXAMPLE ===
 * //Some module...
 * (function () {
 *     var di = window.di;
 *
 *     //Add some dependencies
 *     di.add('a', 'Hello');
 *     di.add('b', 'B');
 *     di.add('c', 'world');
 * }());
 *
 *
 * //Some other module...
 * (function () {
 *     var di = window.di;
 *
 *     //Inject and call later
 *     var injected = di.inject(log);   //or di.inject(log, 'more args');
 *     injected();                      //or injected('even more args');
 *
 *     //Call directly
 *     di.call(log);                    //or di.call(log, 'more args');
 *
 *     //Test function
 *     function log(a, x, c) {
 *         console.log([].slice.call(arguments));
 *         return [a, c].join(' ');
 *     }
 * }());
 */
(function () {

    'use strict';

    var di = {},
        registry = {},
        arraySlice = Array.prototype.slice,
        //Not so standardized in ES3/ES5 - might break ...
        functionToString = Function.prototype.toString;

    function injector(immediate, fn) {
        var args, extras;
        if (!isFunction(fn)) {
            throw new TypeError;
        }
        args = parse(fn).map(resolve);
        extras = arraySlice.call(arguments, 2);
        return immediate ? fn.apply(fn, args.concat(extras)) : function injected() {
            return fn.apply(fn, args.concat(extras, arraySlice.call(arguments)));
        };
    }

    function add(key, value) {
        registry[key] = value;
    }

    function resolve(key) {
        return registry[key];
    }

    function parse(fn) {
        var argsPattern = /\(([^\)]*)/,
            separatorPattern = /\s*,\s*/,
            match = functionToString.call(fn).match(argsPattern);
        if (match && match.length > 1) {
            return match[1].split(separatorPattern);
        }
        return [];
    }

    function isFunction(value) {
        return typeof value === 'function';
    }

    di.add = add;
    di.inject = injector.bind(this, false);
    di.call = injector.bind(this, true);

    this.di = di;

}.call(this));