diff --git a/CHANGELOG b/CHANGELOG
index 2aefa54..5eef4dd 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -1,5 +1,7 @@
 *SVN*
 
+* Update Template, Selector, Ajax.*, and ObjectRange classes to use the new class system.  [Mislav Marohnić]
+
 * Change Abstract.TimedObserver to subclass PeriodicalExecuter and tweak its subclasses to use new inheritance functionality.  TimedObserver can now be stopped the same way as PeriodicalExecuter.  Closes #8589.  [Mislav Marohnić]
 
 * Fix Class.mixin to extend the class's prototype.  [Mislav Marohnić]
diff --git a/src/ajax.js b/src/ajax.js
index 1234768..e2a8998 100644
--- a/src/ajax.js
+++ b/src/ajax.js
@@ -40,17 +40,12 @@ Ajax.Responders = {
 Object.extend(Ajax.Responders, Enumerable);
 
 Ajax.Responders.register({
-  onCreate: function() {
-    Ajax.activeRequestCount++;
-  }, 
-  onComplete: function() {
-    Ajax.activeRequestCount--;
-  }
+  onCreate:   function() { Ajax.activeRequestCount++ }, 
+  onComplete: function() { Ajax.activeRequestCount-- }
 });
 
-Ajax.Base = function() { };
-Ajax.Base.prototype = {
-  setOptions: function(options) {
+Ajax.Base = Class.create({
+  initialize: function(options) {
     this.options = {
       method:       'post',
       asynchronous: true,
@@ -66,18 +61,14 @@ Ajax.Base.prototype = {
     if (Object.isString(this.options.parameters)) 
       this.options.parameters = this.options.parameters.toQueryParams();
   }
-};
+});
 
-Ajax.Request = Class.create();
-Ajax.Request.Events = 
-  ['Uninitialized', 'Loading', 'Loaded', 'Interactive', 'Complete'];
-
-Ajax.Request.prototype = Object.extend(new Ajax.Base(), {
+Ajax.Request = Class.create(Ajax.Base, {
   _complete: false,
   
-  initialize: function(url, options) {
+  initialize: function($super, url, options) {
+    $super(options);
     this.transport = Ajax.getTransport();
-    this.setOptions(options);
     this.request(url);
   },
 
@@ -233,8 +224,10 @@ Ajax.Request.prototype = Object.extend(new Ajax.Base(), {
   }
 });
 
-Ajax.Response = Class.create();
-Ajax.Response.prototype = {
+Ajax.Request.Events = 
+  ['Uninitialized', 'Loading', 'Loaded', 'Interactive', 'Complete'];
+
+Ajax.Response = Class.create({
   initialize: function(request){
     this.request = request;
     var transport  = this.transport  = request.transport,
@@ -301,27 +294,23 @@ Ajax.Response.prototype = {
       this.request.dispatchException(e);
     }
   }
-};
+});
 
-Ajax.Updater = Class.create();
-
-Object.extend(Object.extend(Ajax.Updater.prototype, Ajax.Request.prototype), {
-  initialize: function(container, url, options) {
+Ajax.Updater = Class.create(Ajax.Request, {
+  initialize: function($super, container, url, options) {
     this.container = {
       success: (container.success || container),
       failure: (container.failure || (container.success ? null : container))
     };
-    
-    this.transport = Ajax.getTransport();
-    this.setOptions(options);
 
-    var onComplete = this.options.onComplete || Prototype.emptyFunction;
-    this.options.onComplete = (function(response, param) {
+    options = options || { };
+    var onComplete = options.onComplete;
+    options.onComplete = (function(response, param) {
       this.updateContent(response.responseText);
-      onComplete(response, param);
+      if (Object.isFunction(onComplete)) onComplete(response, param);
     }).bind(this);
 
-    this.request(url);
+    $super(url, options);
   },
 
   updateContent: function(responseText) {
@@ -347,10 +336,9 @@ Object.extend(Object.extend(Ajax.Updater.prototype, Ajax.Request.prototype), {
   }
 });
 
-Ajax.PeriodicalUpdater = Class.create();
-Ajax.PeriodicalUpdater.prototype = Object.extend(new Ajax.Base(), {
-  initialize: function(container, url, options) {
-    this.setOptions(options);
+Ajax.PeriodicalUpdater = Class.create(Ajax.Base, {
+  initialize: function($super, container, url, options) {
+    $super(options);
     this.onComplete = this.options.onComplete;
 
     this.frequency = (this.options.frequency || 2);
diff --git a/src/range.js b/src/range.js
index 373d5b1..f971883 100644
--- a/src/range.js
+++ b/src/range.js
@@ -1,6 +1,4 @@
-ObjectRange = Class.create();
-Object.extend(ObjectRange.prototype, Enumerable);
-Object.extend(ObjectRange.prototype, {
+ObjectRange = Class.create({
   initialize: function(start, end, exclusive) {
     this.start = start;
     this.end = end;
@@ -13,17 +11,19 @@ Object.extend(ObjectRange.prototype, {
       iterator(value);
       value = value.succ();
     }
-  },
-  
-  include: function(value) {
-    if (value < this.start) 
-      return false;
-    if (this.exclusive)
-      return value < this.end;
-    return value <= this.end;
-  }
+  } 
 });
 
+Object.extend(ObjectRange.prototype, Enumerable);
+
+ObjectRange.prototype.include = function(value) {
+  if (value < this.start) 
+    return false;
+  if (this.exclusive)
+    return value < this.end;
+  return value <= this.end;
+};
+
 var $R = function(start, end, exclusive) {
   return new ObjectRange(start, end, exclusive);
-};
\ No newline at end of file
+};
diff --git a/src/selector.js b/src/selector.js
index cdd922f..286f334 100644
--- a/src/selector.js
+++ b/src/selector.js
@@ -2,9 +2,7 @@
  * part of YUI-Ext version 0.40, distributed under the terms of an MIT-style
  * license.  Please see http://www.yui-ext.com/ for more information. */
 
-var Selector = Class.create();
-
-Selector.prototype = {
+var Selector = Class.create({
   initialize: function(expression) {
     this.expression = expression.strip();
     this.compileMatcher();    
@@ -118,7 +116,7 @@ Selector.prototype = {
   inspect: function() {
     return "#<Selector:" + this.expression.inspect() + ">";
   }
-};
+});
 
 Object.extend(Selector, {
   _cache: { },
diff --git a/src/string.js b/src/string.js
index 4dfb583..11f09ca 100644
--- a/src/string.js
+++ b/src/string.js
@@ -230,9 +230,7 @@ Object.extend(String.prototype.escapeHTML, {
 
 with (String.prototype.escapeHTML) div.appendChild(text);
 
-var Template = Class.create();
-Template.Pattern = /(^|.|\r|\n)(#\{(.*?)\})/;
-Template.prototype = {
+var Template = Class.create({
   initialize: function(template, pattern) {
     this.template = template.toString();
     this.pattern = pattern || Template.Pattern;
@@ -263,4 +261,5 @@ Template.prototype = {
       return before + String.interpret(ctx);
     }.bind(this));
   }
-};
+});
+Template.Pattern = /(^|.|\r|\n)(#\{(.*?)\})/;