如何使用Python中的装饰器创建具有实例化时间变量的新函数/方法

from types import InstanceType
from functools import wraps
import inspect

def dec(func):

   #get the sig of the function
   sig = []
   @wraps(func)
   def wrapper(*args, **kwargs):
      ret = None
      #if this is a method belonging to an object...
      if args and getattr(args[0], func.__name__, None):
         instance, args = args[0], args[1:]
         #if sig of object is not already set
         if not hasattr(instance, "sig"):
            instance.sig = []
         ret = func(instance, *args, **kwargs)
         print "Sig of %s is %s" % (func.__name__, id(instance.sig))
      #else this is a function
      else:
         ret = func(*args, **kwargs)
         print "Sig of %s is %s" % (func.__name__, id(sig))
      return ret

   #modify the doc string
   try:
      docs = inspect.getsourcelines(func)
   except:
      docs = "<unable to fetch defintion>"
   else:
      docs = docs[0][1].rstrip('\n').rstrip(':').lstrip(' ').lstrip('def')
   wrapper.__doc__ = docs + "\n" + (func.__doc__ or '')
   return wrapper

class A(object):
   def __init__(self):
      super(A, self).__init__()

   @dec
   def f(self, x):
      """something"""
      print '%s.f(%s)' % (self, x)


@dec
def myfunc():
   print "myfunc"

@dec
def myfunc2():
   print "myfunc2"

@dec
def myfunc3():
   print "myfunc3"

if __name__ == "__main__":
   list = []
   for x in xrange(3):
      list.append(A())

   [a.f(123) for a in list]
   myfunc()
   myfunc()
   myfunc2()
   myfunc2()
   myfunc3()
   myfunc3()

<__main__.A object at 0x00B9F2D0>.f(123)
Sig of f is 11932616
<__main__.A object at 0x00B9F430>.f(123)
Sig of f is 11925464
<__main__.A object at 0x00B9F450>.f(123)
Sig of f is 11918112
myfunc
Sig of myfunc is 11925624
myfunc
Sig of myfunc is 11925624
myfunc2
Sig of myfunc2 is 11794592
myfunc2
Sig of myfunc2 is 11794592
myfunc3
Sig of myfunc3 is 11925144
myfunc3
Sig of myfunc3 is 11925144