'''示例1: 最简单的函数,表示调用了两次'''
def myfunc():
print("myfunc() called.")
myfunc()
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
# '''示例2: 替换函数(装饰)
# 装饰函数的参数是被装饰的函数对象，返回原函数对象
# 装饰的实质语句: myfunc = deco(myfunc)'''
def deco(func):
print("before myfunc() called.")
func()
print(" after myfunc() called.")
return func
def myfunc():
print(" myfunc() called.")
myfunc = deco(myfunc)
myfunc()
myfunc()
# 第三步：使用语法糖@来装饰函数
def deco(func):
print("before myfunc() called.")
func()
print("after myfunc() called.")
return func
@deco
def myfunc():
print("myfunc() called.")
myfunc()
myfunc()
# 使用语法糖@来装饰函数，相当于“myfunc = deco(myfunc)”但发现新函数只在第一次被调用，且原函数多调用了一次'''
# before myfunc() called.
# myfunc() called.
# after myfunc() called.
# myfunc() 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
def deco(func):
def _deco():
print("before myfunc() called.")
func()
print("after myfunc() called.")
# 不需要返回func，实际上应返回原函数的返回值
return _deco
@deco
def myfunc():
print("myfunc() called.")
return 'ok'
myfunc()
myfunc()
# before myfunc() called.
# myfunc() called.
# after myfunc() called.
# before myfunc() called.
# myfunc() called.
# after myfunc() called.
# 第五步：对带参数的函数进行装饰内嵌包装函数的形参和返回值与原函数相同，装饰函数返回内嵌包装函数对象'''
def deco(func):
def _deco(a, b):
print("before myfunc() called.")
ret = func(a, b)
print(" after myfunc() called. result: %s" % ret)
return ret
return _deco
@deco
def myfunc(a, b):
print(" myfunc(%s,%s) called." % (a, b))
return a + b
myfunc(1, 2)
myfunc(3, 4)
# before myfunc() called.
# myfunc(1,2) called.
# after myfunc() called. result: 3
# before myfunc() called.
# myfunc(3,4) called.
# after myfunc() called. result: 7
# 第六步：对参数数量不确定的函数进行装饰参数用(*args, **kwargs)，自动适应变参和命名参数'''
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)
myfunc(3, 4)
myfunc2(1, 2, 3)
myfunc2(3, 4, 5)
# before myfunc called.
# myfunc(1,2) called.
# after myfunc called. result: 3
# before myfunc called.
# myfunc(3,4) called.
# after myfunc called. result: 7
# before myfunc2 called.
# myfunc2(1,2,3) called.
# after myfunc2 called. result: 6
# before myfunc2 called.
# myfunc2(3,4,5) called.
# after myfunc2 called. result: 12
# 第七步：让装饰器带参数和上一示例相比在外层多了一层包装。
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()
# 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()
# before myfunc called [<class '__main__.locker'>].
# locker.acquire() called.（这是静态方法）
# myfunc() called.
# locker.release() called.（不需要对象实例）
# before myfunc called [<class '__main__.locker'>].
# locker.acquire() called.（这是静态方法）
# myfunc() called.
# locker.release() called.（不需要对象实例）
# 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
# '''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))
#
# 下面是参考资料，当初有不少地方没看明白，真正练习后才明白些：
#
# 1. Python装饰器学习 http://blog.csdn.net/thy38/article/details/4471421
#
# 2. Python装饰器与面向切面编程 http://www.cnblogs.com/huxi/archive/2011/03/01/1967600.html
#
# 3. Python装饰器的理解 http://apps.hi.baidu.com/share/detail/17572338
# 类方法，实例方法，静态方法区别演示代码
# 经常有一些跟类有关系的功能但在运行时又不需要实例和类参与的情况下需要用到静态方法. 比如更改环境变量或者修改其他类的属性等能用到静态方法. 这种情况可以直接用函数解决,
# 1 类内部使用
# 2 写在类的定义里，@staticmethod写在函数正上方
# 3 参数的第一个参数不是self
# 4 通过类名字调用实例方法针对的是实例，类方法针对的是类，他们都可以继承和重新定义，静态方法也能继承(NND)，可以认为是全局函数。
class Hero:
@staticmethod
def say_hello():
print("Helllo...")
@classmethod
def say_class_hello(cls):
if(cls.__name__=="HeroSon"):
print("Hi Kido")
elif(cls.__name__=="HeroDaughter"):
print("Hi Princess")
class HeroSon(Hero):
def say_son_hello(self):
print("test hello")
class HeroDaughter(Hero):
def say_daughter_hello(self):
print("test hello daughter")
testson = HeroSon()
testson.say_class_hello() #Output: "Hi Kido"
testson.say_hello() #Outputs: "Helllo..."
testdaughter = HeroDaughter()
testdaughter.say_class_hello() #Outputs: "Hi Princess"
testdaughter.say_hello() #Outputs: "Helllo..."
