Python Decorators - The correct way to do it

Was going through Graham Dumpleton's blog post - how you implemented your python decorator is wrong. Simple points that were discussed were -

• Decorators can be functions as well as Classes.
  

  As a class -  

  
  

  class function_wrapper(object):
      def __init__(self, wrapped):
          self.wrapped = wrapped
      def __call__(self, *args, **kwargs):
          return self.wrapped(*args, **kwargs) 

  @function_wrapper
  def function():
      pass 

  
  

  As a function 

  
  

  def function_wrapper(wrapped):
      def _wrapper(*args, **kwargs):
          return wrapped(*args, **kwargs)
      return _wrapper 

  @function_wrapper
  def function():
      pass 

  
  

• Use the functools.wraps decorator , it only preserves original functions __name__ and __class__
  

  In functions 

  
  

  import functools 

  def function_wrapper(wrapped):
      @functools.wraps(wrapped)
      def _wrapper(*args, **kwargs):
          return wrapped(*args, **kwargs)
      return _wrapper 

  @function_wrapper
  def function():
      pass 

  
  

  In classes, use the update_wrapper method- 

  
  

  import functools 

  class function_wrapper(object):
      def __init__(self, wrapped):
          self.wrapped = wrapped
          functools.update_wrapper(self, wrapped)
      def __call__(self, *args, **kwargs):
          return self.wrapped(*args, **kwargs)

• Python 2.7 preserves Argument specification ( inspect.getargspec ) only in functional decorators, not in class based ones.
• Doesnt preserve function source code for inspection ( inspect.getsource ) 
• Cannot apply decorators on top of other decorators that are implemented as descriptors.