python函数装饰器用法实例详解

#! coding=utf-8 
import time 
def timeit(func): 
  def wrapper(a): 
    start = time.clock() 
    func(1,2) 
    end =time.clock() 
    print 'used:', end - start 
    print a 
  return wrapper 
@timeit
# foo = timeit(foo)完全等价, 
# 使用之后,foo函数就变了，相当于是wrapper了 
def foo(a,b): 
  pass 
#不带参数的装饰器 
# wraper 将fn进行装饰，return wraper ,返回的wraper 就是装饰之后的fn 
def test(func): 
  def wraper(): 
    print "test start" 
    func() 
    print "end start" 
  return wraper 
@test 
def foo(): 
  print "in foo" 
foo() 

test start 
in foo 
end start 

def parameter_test(func): 
  def wraper(a): 
    print "test start" 
    func(a) 
    print "end start" 
  return wraper 
@parameter_test 
def parameter_foo(a): 
  print "parameter_foo:"+a 
#parameter_foo('hello') 

>>> 
test start 
parameter_foo:hello 
end start 

def much_test(func): 
  def wraper(*args, **kwargs): 
    print "test start" 
    func(*args, **kwargs) 
    print "end start" 
  return wraper 
@much_test 
def much1(a): 
  print a 
@much_test 
def much2(a,b,c,d ): 
  print a,b,c,d 
much1('a') 
much2(1,2,3,4) 

test start 
a 
end start 
test start 
1 2 3 4 
end start 

def tp(name,age): 
  def much_test(func): 
    print 'in much_test' 
    def wraper(*args, **kwargs): 
      print "test start" 
      print str(name),'at:'+str(age) 
      func(*args, **kwargs) 
      print "end start" 
    return wraper 
  return much_test 
@tp('one','10') 
def tpTest(parameter): 
  print parameter 
tpTest('python....') 

in much_test 
test start 
one at:10 
python.... 
end start 

class locker: 
  def __init__(self): 
    print("locker.__init__() should be not called.") 
  @staticmethod 
  def acquire(): 
    print("locker.acquire() called.（这是静态方法）") 
  @staticmethod 
  def release(): 
    print("locker.release() called.（不需要对象实例") 
def deco(cls): 
  '''cls 必须实现acquire和release静态方法''' 
  def _deco(func): 
    def __deco(): 
      print("before %s called [%s]." % (func.__name__, cls)) 
      cls.acquire() 
      try: 
        return func() 
      finally: 
        cls.release() 
    return __deco 
  return _deco 
@deco(locker) 
def myfunc(): 
  print(" myfunc() called.") 
myfunc() 

>>> 
before myfunc called [__main__.locker].
locker.acquire() called.（这是静态方法）
 myfunc() called.
locker.release() called.（不需要对象实例
>>> 

class mylocker: 
  def __init__(self): 
    print("mylocker.__init__() called.") 
  @staticmethod 
  def acquire(): 
    print("mylocker.acquire() called.") 
  @staticmethod 
  def unlock(): 
    print(" mylocker.unlock() called.") 
class lockerex(mylocker): 
  @staticmethod 
  def acquire(): 
    print("lockerex.acquire() called.") 
  @staticmethod 
  def unlock(): 
    print(" lockerex.unlock() called.") 
def lockhelper(cls): 
  '''cls 必须实现acquire和release静态方法''' 
  def _deco(func): 
    def __deco(*args, **kwargs): 
      print("before %s called." % func.__name__) 
      cls.acquire() 
      try: 
        return func(*args, **kwargs) 
      finally: 
        cls.unlock() 
    return __deco 
  return _deco 
class example: 
  @lockhelper(mylocker) 
  def myfunc(self): 
    print(" myfunc() called.") 
  @lockhelper(mylocker) 
  @lockhelper(lockerex) 
  def myfunc2(self, a, b): 
    print(" myfunc2() called.") 
    return a + b 
if __name__=="__main__": 
  a = example() 
  a.myfunc() 
  print(a.myfunc()) 
  print(a.myfunc2(1, 2)) 
  print(a.myfunc2(3, 4))

before myfunc called.
mylocker.acquire() called.
 myfunc() called.
 mylocker.unlock() called.
before myfunc called.
mylocker.acquire() called.
 myfunc() called.
 mylocker.unlock() called.
None
before __deco called.
mylocker.acquire() called.
before myfunc2 called.
lockerex.acquire() called.
 myfunc2() called.
 lockerex.unlock() called.
 mylocker.unlock() called.
3
before __deco called.
mylocker.acquire() called.
before myfunc2 called.
lockerex.acquire() called.
 myfunc2() called.
 lockerex.unlock() called.
 mylocker.unlock() called.
7