deco.py

In [1]: def deco(arg):
   ...:         def wrapper(func):
   ...:                 def _wrapper():
   ...:                         return func(arg)
   ...:                 return _wrapper
   ...:         return wrapper
   ...: 

In [2]: @deco("ham")
   ...: def spam(egg):
   ...:     print egg
   ...:     

In [3]: spam()
ham

deco2.py

In [1]: def deco(func):                                                                                                                                                                                                                                                        
   ...:         def wrap():                                                                                                                                                                                                                                                        
   ...:                 return func                                                                                                                                                                                                                                                    
   ...:         wrap.hoge = "hoge"                                                                                                                                                                                                                                                 
   ...:         return wrap                                                                                                                                                                                                                                                        
   ...:                                                                                                                                                                                                                                                                        

In [2]: @deco                                                                                                                                                                                                                                                                  
   ...: def hoge():                                                                                                                                                                                                                                                            
   ...:         print hoge.hoge
   ...:     

In [3]: h = hoge()

In [4]: h()
hoge