Refactored constructor creation logic for new classes into its own method and placed both functions (and their shared var) into a closure to remove the 'extending' var from the module's scope

lib/class.js

@@ -81,77 +81,102 @@ function Class() {};
 
 
 /**
- * Set to TRUE when class is being extended to allow the instantiation of
- * abstract classes (for use in prototypes)
+ * Creates extend function
  *
- * @var  {boolean}
+ * The 'extending' parameter is used to override the functionality of abstract
+ * class constructors, allowing them to be instantiated for use in a subclass's
+ * prototype.
+ *
+ * @param  {boolean}  extending  whether a class is currently being extended
+ *
+ * @return  {Function}  extend function
  */
-var extending = false;
-
-/**
- * Mimics class inheritance
- *
- * This method will mimic inheritance by setting up the prototype with the
- * provided base class (or, by default, Class) and copying the additional
- * properties atop of it.
- *
- * The class to inherit from (the first argument) is optional. If omitted, the
- * first argument will be considered to be the properties list.
- *
- * @return  {Object}  extended class
- */
-function extend()
+var extend = ( function( extending )
 {
-    // ensure we'll be permitted to instantiate abstract classes for the base
-    extending = true;
+    extending = false;
 
-    var args      = Array.prototype.slice.call( arguments ),
-        props     = args.pop() || {},
-        base      = args.pop() || Class,
-        prototype = new base();
+    /**
+     * Mimics class inheritance
+     *
+     * This method will mimic inheritance by setting up the prototype with the
+     * provided base class (or, by default, Class) and copying the additional
+     * properties atop of it.
+     *
+     * The class to inherit from (the first argument) is optional. If omitted, the
+     * first argument will be considered to be the properties list.
+     *
+     * @return  {Object}  extended class
+     */
+    return function extend()
+    {
+        // ensure we'll be permitted to instantiate abstract classes for the base
+        extending = true;
 
-    // copy the given properties into the new prototype
-    var result_data = {
-        abstractMethods: ( base.abstractMethods || [] ).slice()
-    };
-    prop_copy( props, prototype, result_data );
+        var args      = Array.prototype.slice.call( arguments ),
+            props     = args.pop() || {},
+            base      = args.pop() || Class,
+            prototype = new base();
 
-    // reference to the parent prototype (for more experienced users)
-    prototype.parent = base.prototype;
+        // copy the given properties into the new prototype
+        var result_data = {
+            abstractMethods: ( base.abstractMethods || [] ).slice()
+        };
+        prop_copy( props, prototype, result_data );
 
-    var new_class = ( result_data.abstractMethods.length === 0 )
-        ? (
-            // concrete class
-            function()
+        // reference to the parent prototype (for more experienced users)
+        prototype.parent = base.prototype;
+
+        // set up the new class
+        var new_class = create_ctor( result_data, extending );
+
+        setup_props( new_class, result_data );
+        new_class.prototype   = prototype;
+        new_class.constructor = new_class;
+
+        // we're done with the extension process
+        extending = false;
+
+        return new_class;
+    }
+
+
+    /**
+     * Creates the constructor for a new class
+     *
+     * This constructor will call the __constructor method for concrete classes
+     * and throw an exception for abstract classes (to prevent instantiation).
+     *
+     * @param  {Object}  result_data  data from property copy operation
+     *
+     * @return  {Function}  constructor
+     */
+    function create_ctor( result_data )
+    {
+        // concrete class
+        if ( result_data.abstractMethods.length === 0 )
+        {
+            return function()
             {
                 if ( this.__construct instanceof Function )
                 {
                     // call the constructor
                     this.__construct.apply( this, arguments );
                 }
-            }
-        )
-        : (
-            // do not allow abstract classes to be instantiated
-            function ()
+            };
+        }
+        // abstract class
+        else
+        {
+            return function ()
             {
                 if ( !extending )
                 {
                     throw new Error( "Abstract classes cannot be instantiated" );
                 }
-            }
-        );
-
-    // set up the new class
-    setup_props( new_class, result_data );
-    new_class.prototype   = prototype;
-    new_class.constructor = new_class;
-
-    // we're done with the extension process
-    extending = false;
-
-    return new_class;
-}
+            };
+        }
+    }
+} )();
 
 
 /**