Merge branch 'release/4.2.7'

package.json

@@ -2,7 +2,7 @@
 	"name": "qoopido.demand",
 	"title": "Qoopido.demand",
 	"description": "Promise like module loader using XHR requests and localStorage caching to dynamically load JavaScript and CSS + dynamic dependency resolution + support for custom handlers",
-	"version": "4.2.6",
+	"version": "4.2.7",
 	"homepage": "https://github.com/dlueth/qoopido.demand",
 	"author": {
 		"name": "Dirk Lueth",

src/inheritance.js

@@ -1,34 +1,45 @@
 /* global
 	global, document, demand, provide, queue, processor, settings, setTimeout, clearTimeout, storage,
+	TRUE,
 	objectCreate, objectDefineProperty, objectGetOwnPropertyNames, objectGetOwnPropertyDescriptor,
 	ClassDescriptor
 */
 
+//=require constants.js
 //=require shortcuts.js
 //=require class/descriptor.js
 
-(function() {
+(function(strPrototype) {
 	var descriptor;
 
-	function extend(parent) {
+	function functionExtends(source) {
 		var self       = this,
-			prototype  = self.prototype,
-			properties = {},
+			prototype  = self[strPrototype],
 			names      = objectGetOwnPropertyNames(prototype),
+			properties = { constructor:  new ClassDescriptor(self, TRUE, TRUE)},
 			i = 0, property;
 
-		for(; (property = names[i]); i++) {
+		for(; (property = names[i]) && !properties[property]; i++) {
 			properties[property] = objectGetOwnPropertyDescriptor(prototype, property);
 		}
 
-		properties.constructor = new ClassDescriptor(self);
-		self.prototype         = objectCreate(parent.prototype || parent, properties);
+		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;
 	}
 
-	descriptor = new ClassDescriptor(extend);
+	descriptor = new ClassDescriptor(functionExtends);
 
 	objectDefineProperty(Function.prototype, 'extends', descriptor);
 	objectDefineProperty(global.Function.prototype, 'extends', descriptor);
-}());
+}('prototype'));