"Creates Sort Descriptors" CPTableColumn value binding option.

With this option an array controller driven table view can be sorted by clicking the table column headers without manually setting up sort descriptor prototypes.

If `CPCreatesSortDescriptorBindingOption` is enabled on a table column value binding, sort descriptors will be created automatically. The default value for this option is YES.

AppKit/CPTableColumn.j

@@ -494,7 +494,13 @@ CPTableColumnUserResizingMask   = 1 << 1;
 */
 - (CPSortDescriptor)sortDescriptorPrototype
 {
-    return _sortDescriptorPrototype;
+    if (_sortDescriptorPrototype)
+        return _sortDescriptorPrototype;
+
+    var binderClass = [[self class] _binderClassForBinding:CPValueBinding],
+        binding = [binderClass getBinding:CPValueBinding forObject:self];
+
+    return [binding _defaultSortDescriptorPrototype];
 }
 
 /*!
@@ -570,6 +576,30 @@ CPTableColumnUserResizingMask   = 1 << 1;
     [tableView reloadDataForRowIndexes:rowIndexes columnIndexes:columnIndexes];
 }
 
+- (CPSortDescriptor)_defaultSortDescriptorPrototype
+{
+    if (![self createsSortDescriptor])
+        return nil;
+
+    var keyPath = [_info objectForKey:CPObservedKeyPathKey],
+        dotIndex = keyPath.lastIndexOf(".");
+
+    if (dotIndex === CPNotFound)
+        return nil;
+
+    var firstPart = keyPath.substring(0, dotIndex),
+        key = keyPath.substring(dotIndex + 1);
+
+    return [CPSortDescriptor sortDescriptorWithKey:key ascending:YES];
+}
+
+- (BOOL)createsSortDescriptor
+{
+    var options = [_info objectForKey:CPOptionsKey],
+        optionValue = [options objectForKey:CPCreatesSortDescriptorBindingOption];
+    return optionValue === nil ? YES : [optionValue boolValue];
+}
+
 @end
 
 @implementation CPTableColumn (Bindings)