dlueth/qoopido.nucleus

(function(strPrototype) {
    'use strict';

    var object                         = Object,
        objectCreate                   = object.create,
        objectGetOwnPropertyNames      = object.getOwnPropertyNames,
        objectGetOwnPropertyDescriptor = object.getOwnPropertyDescriptor,
        objectDefineProperty           = object.defineProperty;

    function functionExtends(source) {
        var self       = this,
            prototype  = self[strPrototype],
            names      = objectGetOwnPropertyNames(prototype),
            properties = { constructor: { value: self, writable: true, configurable: true }},
            i = 0, property;

        for(; (property = names[i]) && !properties[property]; i++) {
            properties[property] = objectGetOwnPropertyDescriptor(prototype, property);
        }

        try {
            self[strPrototype] = objectCreate(source[strPrototype] || source, properties);
        } catch(e) {
            // ES6 class prototypes are readonly at least in Chrome
            // (and assignment throws an error in strict mode) ...
        }

        // ... which is handled here
        if(self[strPrototype] === prototype) {
            throw new TypeError('Unable to extend, prototype is not writable');
        }

        return self;
    }

    objectDefineProperty(Function.prototype, 'extends', functionExtends);
}('prototype'));