python decorator

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decorator

Table of Contents

• 1 decorator
  • 1.1 python中函数可以作为返回值
  • 1.2 函数作为入参
  • 1.3 改写函数
  • 1.4 装饰器改写
  • 1.5 装饰器可以为一个类
  • 1.6 类也可以使用装饰器
  • 1.7 类装饰器改写类

1 decorator

python中的装饰模式器其实就是对函数进行修改,符号为@

1.1 python中函数可以作为返回值

def newFunc():
    return lambda x: x*x

func = newFunc()
print(func(3))

1.2 函数作为入参

def alterFunc(func):
    print('this func is altered ', func.__name__)
    return lambda x: x+1

def myFunc(x):
    return x*x

myFunc = alterFunc(myFunc)

print(myFunc(5))

1.3 改写函数

def logFunc(func):
    print('this func is loged ', func.__name__)
    def wrapper(*args):
        print('%s is called' % func.__name__)
        # args是一个tuple, *args是把tuple展开后作为函数入参
        result = func(*args)
        print('result is ', result)
        return result
    return wrapper

def myFunc(x):
    return x*x

myFunc = logFunc(myFunc)

print(myFunc(6))

1.4 装饰器改写

def logFunc(func):
    print('this func is loged ', func.__name__)
    def wrapper(*args):
        print('%s is called' % func.__name__)
        # args是一个tuple, *args是把tuple展开后作为函数入参
        result = func(*args)
        print('result is ', result)
        return result
    return wrapper

@logFunc
def myFunc(x):
    return x*x

# 和上面等价的
# def myFunc(x):
#     return x*x

# myFunc = logFunc(myFunc)


print(myFunc(6))

1.5 装饰器可以为一个类

class classDecor:
    def __init__(self, func):
        print('init ')
        self.func = func

    def __call__(self, args):
        print('called ', args)
        result = self.func(args)
        print('called over')
        return result

@classDecor
def myFunc2(x):
    return x*x

print(myFunc2(5))

1.6 类也可以使用装饰器

def addFunc(cls):
    def f1(self, x, y):
        return min(x, x+y)
    cls.f = f1
    return cls

@addFunc    
class C:
    def g(self):
        return 'hello world'

c = C()
print(c.g(), c.f(3, 2))

1.7 类装饰器改写类

class clsFunc:
    def __init__(self, cls):
        print 'try wrap class'
        class wrapperCls(cls):
            def f1(self, x, y):
                return min(x, x+y)
        self.obj = wrapperCls()

    def __call__(self):
        print('clsFunc.__call__ called')
        return self.obj

# in decorator, it will call clsFunc.__init__ to wrap class    
@clsFunc    
class D:
    def g(self):
        return 'hello world'

print('in init obj, it will call clsFunc.__call__') 
d = D()

print('in calling funcs')
print(d.g(), d.f1(3, 2))

Date: 2013-04-15 16:03:48 中国标准时间