装饰器作用:

​比如下面一个函数:​

def my_hello():
print('Hello World!')


my_hello()

​现在有一个要求,就是在打印 Hello World! 之前先打印 WTF!​


  • 装饰器:

def my_decorate(func):
def inner():
print('WTF')
func()
return inner

@my_decorate
def my_hello():
print('Hello World!')


my_hello()

好处:解决代码重用,易于修改

​当函数带有参数时:​

def my_decorate(func):
def inner(*args, **kwargs):
print('WTF')
func(*args, **kwargs)
return inner


@my_decorate
def my_hello(str):
print('Hello World! %s' % str)



my_hello('HaHaHa')

​当函数带有返回值时:​

def my_decorate(func):
def inner(*args, **kwargs):
print('WTF')
return func(*args, **kwargs)
return inner


@my_decorate
def my_hello(str, a, b):
print('Hello World! %s' % str)
return a + b



print(my_hello('HaHaHa', 1, 2)) # 当装饰器中没有 return func(*args, **kwargs) 的返回值时,会打印 None ,即空
# 但是当打印函数私有属性 __name__ 时,会发现其变成了装饰器返回的函数名,即 inner
print(my_hello.__name__)

​解决装饰器链式调用重名问题:​

from functools import wraps

def my_decorate(func):
@wraps(func)
def inner(*args, **kwargs):
print('WTF')
return func(*args, **kwargs)
return inner


@my_decorate
def my_hello(str, a, b):
print('Hello World! %s' % str)
return a + b


my_hello('HaHaHa', 1, 2)
print(my_hello.__name__)