连载|想用Python做自动化测试？彻底学会装饰器

def my_decorator(func):  
    def wrapper():
        print('wrapper of decorator')  # ①这里做一通操作
        func()  # ②调用原函数
    return wrapper  # ③返回内部函数对象


def greet():
    print('hello world')


greet = my_decorator(greet)  # 变量 greet 指向了内部函数 wrapper()
greet()  # 调用 greet() 相当于执行内部函数wrapper


@my_decorator  # @语法糖，相当于greet1 = my_decorator(greet1)
def greet1():    
    print('hello world')

def my_decorator(func):  # 这个func只是个参数，不一定是函数名。
    def wrapper(*args, **kwargs):  
        print('wrapper of decorator') # 这里做一通操作
        func(*args, **kwargs)  # 调用原函数
    return wrapper  # 返回内部函数对象


@my_decorator
def greet(message):    
    print(message)


@my_decorator
def celebrate(name, message):
    print(name+message)

def repeat(num):
    def my_decorator(func):
        def wrapper(*args, **kwargs):
            for i in range(num):
                print('wrapper of decorator')
                func(*args, **kwargs)
        return wrapper
    return my_decorator


@repeat(4)
def greet(message):
    print(message)

def type_decorator(**kwargs):
    """检查实例属性类型的装饰器"""
    def decorate(cls):  # 对instance进行装饰
        for key, value in kwargs.items():
            # 给cls的设置类属性，并给类属性设置描述符实例
            setattr(cls, key, TypedAssertion(key, value))
        return cls


    return decorate

@type_decorator(brand=str, shares=int, price=float)
class Stock:
    def __init__(self, brand, shares, price):
        self.brand = brand
        self.shares = shares
        self.price = price

import functools


def my_decorator(func):
    @functools.wraps(func)  # 为了保留被装饰函数的元信息
    def wrapper(*args, **kwargs):
        print('wrapper of decorator')
        func(*args, **kwargs)
    return wrapper
    
@my_decorator
def greet(message):
    print(message)

class Count:
    def __init__(self, func):
        self.func = func
        self.num_calls = 0


    def __call__(self, *args, **kwargs):
        self.num_calls += 1  # 调用次数加1
        print('num of calls is: {}'.format(self.num_calls))
        return self.func(*args, **kwargs)


@Count  # Count类装饰example，会调用Count类的__call__函数
def example():
    print("hello world")


example()


# 输出
num of calls is: 1
hello world


example()


# 输出
num of calls is: 2
hello world

@decorator1
@decorator2
@decorator3
def func():
  ...

import functools


def authenticate(func):
    @functools.wraps(func)
    def wrapper(*args, **kwargs):
        request = args[0]
        if check_user_logged_in(request): # 如果用户处于登录状态
            return func(*args, **kwargs) # 执行函数post_comment() 
        else:
            raise Exception('Authentication failed')
    return wrapper
    
@authenticate
def post_comment(request, ...)
    ...

import time
import functools


def log_execution_time(func):
    @functools.wraps(func)
    def wrapper(*args, **kwargs):
        start = time.perf_counter()
        res = func(*args, **kwargs)
        end = time.perf_counter()
        print('{} took {} ms'.format(func.__name__, (end - start) * 1000))
        return res
    return wrapper
    
@log_execution_time
def calculate_similarity(items):
    ...

import functools


def validation_check(input):
    @functools.wraps(func)
    def wrapper(*args, **kwargs): 
        ... # 检查输入是否合法
    
@validation_check
def neural_network_training(param1, param2, ...):
    ...