装饰器

Python 函数编写

Shayne Miel

Software Architect @ Duo Security

函数

装饰器

带装饰器的函数

修改输入

修改输出

修改函数

装饰器长什么样？

@double_args
def multiply(a, b):
  return a * b

multiply(1, 5)

double_args 装饰器

def multiply(a, b):
  return a * b

def double_args(func):
  return func

new_multiply = double_args(multiply)

new_multiply(1, 5)

multiply(1, 5)

double_args 装饰器

def multiply(a, b):
  return a * b

def double_args(func):

  # 定义可修改的新函数
  def wrapper(a, b):

    # 先调用未修改的函数
    return func(a, b)

  # 返回新函数
  return wrapper

new_multiply = double_args(multiply)

new_multiply(1, 5)

double_args 装饰器

def multiply(a, b):
  return a * b

def double_args(func):
  def wrapper(a, b):

    # 调用传入函数，但将每个参数翻倍
    return func(a * 2, b * 2)

  return wrapper

new_multiply = double_args(multiply)

new_multiply(1, 5)

double_args 装饰器

def multiply(a, b):
  return a * b

def double_args(func):
  def wrapper(a, b):
    return func(a * 2, b * 2)
  return wrapper

multiply = double_args(multiply)

multiply(1, 5)

multiply.__closure__[0].cell_contents

<function multiply at 0x7f0060c9e620>

装饰器语法

def double_args(func):
  def wrapper(a, b):
    return func(a * 2, b * 2)
  return wrapper



def multiply(a, b):
  return a * b

multiply = double_args(multiply)

multiply(1, 5)

def double_args(func):
  def wrapper(a, b):
    return func(a * 2, b * 2)
  return wrapper


@double_args
def multiply(a, b):
  return a * b



multiply(1, 5)

Passons à la pratique !

Python 函数编写