Refactored method override logic into its own function

lib/class.js

@@ -172,31 +172,9 @@ function prop_copy( props, dest, result_data )
         // check for method overrides
         else if ( ( pre !== undefined ) && ( pre instanceof Function ) )
         {
-            // ensure we're overriding the method with another method
+            dest[ property ] = method_override( pre, prop );
-            if ( !( prop instanceof Function ) )
-            {
-                throw new TypeError( "Cannot override method with non-method" );
-            }
-
-            dest[ property ] = ( function( method, super_method )
-            {
-                // this is the method that will be invoked when the requested
-                // method is called, so note that in the context of this
-                // function, `this` will represent the current class instance
-                return function()
-                {
-                    var tmp = this.__super;
-
-                    // assign _super temporarily for the method invocation so
-                    // that the method can call the parent method
-                    this.__super = super_method;
-                    var retval  = method.apply( this, arguments );
-                    this.__super = tmp;
-
-                    return retval;
-                }
-            })( prop, dest[ property ] );
         }
+        // just copy over the property
         else
         {
             dest[ property ] = prop;
@@ -212,6 +190,42 @@ function prop_copy( props, dest, result_data )
 }
 
 
+/**
+ * Overrides a method
+ *
+ * The given method must be a function or an exception will be thrown.
+ *
+ * @param  {Function}  super_method  method to override
+ * @param  {Function}  new_method    method to override with
+ *
+ * @return  {Function}  overridden method
+ */
+function method_override( super_method, new_method )
+{
+    // ensure we're overriding the method with another method
+    if ( !( new_method instanceof Function ) )
+    {
+        throw new TypeError( "Cannot override method with non-method" );
+    }
+
+    // this is the method that will be invoked when the requested
+    // method is called, so note that in the context of this
+    // function, `this` will represent the current class instance
+    return function()
+    {
+        var tmp = this.__super;
+
+        // assign _super temporarily for the method invocation so
+        // that the method can call the parent method
+        this.__super = super_method;
+        var retval  = new_method.apply( this, arguments );
+        this.__super = tmp;
+
+        return retval;
+    }
+}
+
+
 /**
  * Shrinks an array, removing undefined elements
  *
@@ -422,3 +436,4 @@ function attach_extend( func )
     // less restrictive)
     define_secure_prop( func, 'extend', ext_method );
 }
+