def time_this(original_function): 
  def new_function(*args, **kwargs):
    import datetime 
    before = datetime.datetime.now() 
    x = original_function(*args, **kwargs) 
    after = datetime.datetime.now() 
    print("Elapsed Time = {}".format(after-before)) 
    return x 
  return new_function
@time_this
def func_a(stuff): 
  import time 
  time.sleep(stuff) 
  func_a(3)
# out:
Elapsed Time = 0:00:03.012472

@view_config(route_name='home', renderer='templates/mytemplate.pt')
def my_view(request): 
  return {'project': 'hello decorators'} 

# 假設(shè)這些函數(shù)是存在的
def current_user_id(): 
  """ this function returns the current logged in user id, if the use is not authenticated the return None """
def get_permissions(iUserId): 
  """ returns a list of permission strings for the given user. For example ['logged_in','administrator','premium_member'] """
# 在這些函數(shù)中我們需要實(shí)現(xiàn)權(quán)限檢查 
def delete_user(iUserId): 
  """ delete the user with the given Id. This function is only accessable to users with administrator permissions """ 
def new_game(): 
  """ any logged in user can start a new game """ 
def premium_checkpoint(): 
  """ save the game progress, only accessable to premium members """

def requires_admin(fn): 
  def ret_fn(*args,**kwargs): 
    lPermissions = get_permissions(current_user_id()) 
    if 'administrator' in lPermissions: 
      return fn(*args,**kwargs) 
    else: raise Exception("Not allowed") 
  return ret_fn
def requires_logged_in(fn): 
  def ret_fn(*args,**kwargs): 
    lPermissions = get_permissions(current_user_id()) 
    if 'logged_in' in lPermissions: 
      return fn(*args,**kwargs) 
    else: 
      raise Exception("Not allowed") 
    return ret_fn 
def requires_premium_member(fn): 
  def ret_fn(*args,**kwargs): 
    lPermissions = get_permissions(current_user_id()) 
    if 'premium_member' in lPermissions: 
      return fn(*args,**kwargs) 
    else: 
      raise Exception("Not allowed") 
    return ret_fn 
@requires_admin
def delete_user(iUserId): 
""" delete the user with the given Id. This function is only accessable to users with administrator permissions """
@requires_logged_in
def new_game(): 
""" any logged in user can start a new game """ @requires_premium_member
def premium_checkpoint(): 
""" save the game progress, only accessable to premium members """

def requires_permission(sPermission): 
  def decorator(fn): 
    def decorated(*args,**kwargs): 
      lPermissions = get_permissions(current_user_id()) 
      if sPermission in lPermissions: 
        return fn(*args,**kwargs)
      raise Exception("permission denied") 
    return decorated 
  return decorator
def get_permissions(iUserId): 
  # this is here so that the decorator doesn't throw NameErrors 
  return ['logged_in',]
def current_user_id(): 
  #ditto on the NameErrors 
  return 1
#and now we can decorate stuff... 
@requires_permission('administrator')
def delete_user(iUserId): 
""" delete the user with the given Id. This function is only accessible to users with administrator permissions """
@requires_permission('logged_in')
def new_game(): 
""" any logged in user can start a new game """ @requires_permission('premium_member')
def premium_checkpoint(): 
""" save the game progress, only accessable to premium members """

def outer_decorator(*outer_args,**outer_kwargs): 
  def decorator(fn): 
    def decorated(*args,**kwargs):
      do_something(*outer_args,**outer_kwargs) 
      return fn(*args,**kwargs) 
    return decorated 
  return decorator 
@outer_decorator(1,2,3)
def foo(a,b,c): 
  print(a) 
  print(b) 
  print(c)
foo()

def decorator(fn): 
  def decorated(*args,**kwargs): 
    do_something(1,2,3) 
    return fn(*args,**kwargs) 
  return decorated 
return decorator 
@decorator
def foo(a,b,c): 
  print(a)
  print(b) 
  print(c)
foo()

class ImportantStuff(object): 
@time_this 
def do_stuff_1(self): 
  pass
@time_this 
def do_stuff_2(self): 
  pass
@time_this 
def do_stuff_3(self): 
  pass

@time_all_class_methods
class ImportantStuff: 
  def do_stuff_1(self):
    pass
  def do_stuff_2(self):
    pass
  def do_stuff_3(self):
    pass

class ImportantStuff: 
  def do_stuff_1(self):
    pass
  def do_stuff_2(self):
    pass
  def do_stuff_3(self):
    pass
ImportantStuff = time_all_class_methods(ImportantStuff)

def time_this(original_function): 
  print("decorating") 
  def new_function(*args,**kwargs): 
    print("starting timer") 
    import datetime 
    before = datetime.datetime.now() 
    x = original_function(*args,**kwargs) 
    after = datetime.datetime.now() 
    print("Elapsed Time = {0}".format(after-before)) 
    return x 
  return new_function
def time_all_class_methods(Cls): 
  class NewCls: 
    def __init__(self,*args,**kwargs): 
      self.oInstance = Cls(*args,**kwargs) 
    def __getattribute__(self,s): 
      try: 
        x = super(NewCls,self).__getattribute__(s) 
      except AttributeError: 
        pass 
      else: 
        return x 
      x = self.oInstance.__getattribute__(s) 
      if type(x) == type(self.__init__): 
        return time_this(x) 
      else: 
        return x 
    return NewCls
@time_all_class_methods
class Foo: 
  def a(self): 
    print("entering a") 
    import time 
    time.sleep(3) 
    print("exiting a")
oF = Foo()
oF.a()
# out：
decorating
starting timer
entering a
exiting a
Elapsed Time = 0:00:03.006767