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