python decorator 小记

python的装饰器模式有点像java的拦截器（AOP）其中分为两种：1.无参数装饰器

deffoo(func):

"""无参数装饰器"""

@functools.wraps(func)

defprocess(*args,**kwargs):

try:

result=func(*args,**kwargs)

returnresult

exceptExceptionasex:

print(ex)

returnprocess

@foo

deftest(val):

print('test %s'%val)

if__name__=='__main__':

test()

"""

相当于不带装饰器

foo(test)(val)

"""

2.带参数的装饰器

deffoo(ext=None):

"""带参数装饰器"""

defprocess(func):

@functools.wraps(func)

definner(*args,**kwargs):

try:

result=func(*args,**kwargs)

print(ext)

returnresult

exceptExceptionasex:

print(ex)

returninner

returnprocess

@foo(ext='ext')

deftest(val):

print('test %s'%val)

if__name__=='__main__':

test('this')

"""

相当于不带装饰器

foo(ext='ext')(test)('this')

"""3.支持带参数和不带参数

deffoo(decorator_=None,ext=None):

"""带参数不带参数均可"""

ifdecorator_andext:

raiseException('args not match')

defprocess(func):

@functools.wraps(func)

definner(*args,**kwargs):

rt=func(*args,**kwargs)

print('ext is %s'%ext)

returnrt

returninner

ifdecorator_:

returnprocess(decorator_)

else:

returnprocess

@foo#相当于foo(test)(val)

@foo(ext='test')#相当于foo(ext='test')(test)(val)

deftest(val):

print('test %s'%val)

return{'status':'done','name':'JIM'}functools.wraps 可以将原函数对象的指定属性复制给包装函数对象, 默认有、、,或者通过参数选择。

>>>fromfunctoolsimportpartial

>>>deffoo(x,y,z):

...print(locals())

...

>>>foo(1,2,3)

{'x':1,'z':3,'y':2}

>>>foo_z=partial(foo,z=5)

>>>foo_z

functools.partial(,z=5)

>>>foo_zisfoo

False

>>>foo_z(10,20)

{'x':10,'z':5,'y':20}

>>>