old_contents: from datetime import datetime
  
  from django.db import models
  
  class AutoCreatedField (models.DateTimeField):
      """
      A DateTimeField that automatically populates itself at
      object creation.
  
      By default, sets editable=False, default=datetime.now.
  
      """
      def __init__ (self, *args, **kwargs):
          kwargs.setdefault('editable', False)
          kwargs.setdefault('default', datetime.now)
          super(AutoCreatedField, self).__init__(*args, **kwargs)
  
  class AutoLastModifiedField (AutoCreatedField):
      """
      A DateTimeField that updates itself on each save() of the model.
  
      By default, sets editable=False and default=datetime.now.
      
      """
      def pre_save (self, model_instance, add):
          value = datetime.now()
          setattr(model_instance, self.attname, value)
          return value    
      
  
new_contents: from datetime import datetime
  
  from django.db import models
  
  class AutoCreatedField (models.DateTimeField):
      """
      A DateTimeField that automatically populates itself at
      object creation.
  
      By default, sets editable=False, default=datetime.now.
  
      """
      def __init__ (self, *args, **kwargs):
          kwargs.setdefault('editable', False)
          kwargs.setdefault('default', datetime.now)
          super(AutoCreatedField, self).__init__(*args, **kwargs)
  
  class AutoLastModifiedField (AutoCreatedField):
      """
      A DateTimeField that updates itself on each save() of the model.
  
      By default, sets editable=False and default=datetime.now.
      
      """
      def pre_save (self, model_instance, add):
          value = datetime.now()
          setattr(model_instance, self.attname, value)
          return value    
      
  # allow South to handle these fields smoothly
  try:
      from south.modelsinspector import add_introspection_rules
      add_introspection_rules(patterns=['model_utils\.fields\.'])
  except ImportError:
      pass
  
  
subject: support South for custom fields