python装饰器
转自http://www.cnblogs.com/rhcad/archive/2011/12/21/2295507.html
第一步：最简单的函数，准备附加额外功能
[root@python day4]# cat dec1.py #!/usr/bin/env python def myfunc(): print "myfunc() called." myfunc()
第二步：使用装饰函数在函数执行前和执行后分别附加额外功能
[root@python day4]# cat dec1.py #!/usr/bin/env python def myfunc(): print "myfunc() called." def deco(func): print "beforce myfunc() called." func() print "after mufunc() called." return func myfunc = deco(myfunc) myfunc() #执行结果 [root@python day4]# python dec1.py beforce myfunc() called. myfunc() called. after mufunc() called. myfunc() called.
第三步：使用语法糖@来装饰函数
#!/usr/bin/env python def deco(func): #定义好装饰器 print "beforce myfunc() called." func() print "after mufunc() called." return func @deco #引用装饰器 def myfunc(): print "myfunc() called." myfunc() #执行结果 [root@python day4]# python dec1.py beforce myfunc() called. myfunc() called. after mufunc() called. myfunc() called.
第四步：使用内嵌包装函数来确保每次新函数都被调用
[root@python day4]# cat dec1.py #!/usr/bin/env python def deco(func): def _deco(): print "before myfunc() called." func() print "after myfunc() called." return _deco @deco def myfunc(): print "myfunc called." return "ok" myfunc() #执行结果 [root@python day4]# python dec1.py before myfunc() called. myfunc called. after myfunc() called.
第五步：对带参数的函数进行装饰
[root@python day4]# cat dec1.py #!/usr/bin/env python def deco(func): def _deco(a,b): print "before myfunc() called." ret = func(a,b) print "after mufunc() called. result: %s" % ret return ret return _deco @deco def myfunc(a,b): print "myfunc(%s,%s) called." % (a,b) return a + b myfunc(3,4) #执行结果 [root@python day4]# python dec1.py before myfunc() called. myfunc(3,4) called. after mufunc() called. result: 7
第六步：对参数数量不确定的函数进行装饰
[root@python day4]# cat dec2.py #!/usr/bin/env python def deco(func): def _deco(*args,**kwargs): print "before %s called." % func.__name__ ret = func(*args,**kwargs) print "after %s called. result: %s" % (func.__name__,ret) return ret return _deco @deco def myfunc(a,b): print "myfunc(%s,%s) called." % (a,b) return a + b @deco def myfunc2(a,b,c): print "myfunc2(%s,%s,%s) called." % (a,b,c) return a + b + c myfunc(1,2) myfunc2(3,4,5) #执行结果 [root@python day4]# python dec2.py before myfunc called. myfunc(1,2) called. after myfunc called. result: 3 before myfunc2 called. myfunc2(3,4,5) called. after myfunc2 called. result: 12
第七步：让装饰器带参数
[root@python day4]# cat dec3.py
#!/usr/bin/env python
def deco(arg):
def _deco(func):
def __deco():
print("before %s called [%s]." % (func.__name__, arg))
func()
print(" after %s called [%s]." % (func.__name__, arg))
return __deco
return _deco
@deco("mymodule")
def myfunc():
print(" myfunc() called.")
@deco("module2")
def myfunc2():
print(" myfunc2() called.")
myfunc()
myfunc2()
[root@python day4]# python dec3.py
before myfunc called [mymodule].
myfunc() called.
after myfunc called [mymodule].
before myfunc2 called [module2].
myfunc2() called.
after myfunc2 called [module2].
第八步：让装饰器带 类 参数
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()
myfunc()
第九步：装饰器带类参数，并分拆公共类到其他py文件中，同时演示了对一个函数应用多个装饰器
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
# -*- coding:gbk -*-
'''示例9: 装饰器带类参数，并分拆公共类到其他py文件中
同时演示了对一个函数应用多个装饰器'''
from mylocker import *
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))