# /usr/bin/python
# -*- coding:utf-8 -*-
from time import time
def logged(when):
  def log(f,*args,**kargs):
    print '''
         called:
          functions:%s
          args: %r
          kargs: %r
    '''  % (f,args,kargs)
  def pre_logged(f):
    def wrapper(*args,**kargs):
      log(f,*args,**kargs)
      return f(*args,**kargs)
    return wrapper
  def post_logged(f):
    def wrapper(*args,**kargs):
      now = time()
      try:
        return f(*args,**kargs)
      finally:
        log(f,*args,**kargs)
        print "time delta:%s" % (time()-now)
    return wrapper
  try:
    return {"pre":pre_logged,"post":post_logged}[when]
  except KeyError,e:
    raise ValueError(e),'must be "pre" or "post"'
@logged("post")
def hello(name):
  print "hello,",name
hello("world!")
'''
等同于： hello = logged("post")(hello("world!"))
'''