Python高阶精讲之闭包与装饰器彻底吃透(零基础看懂+实战源码)

# 1. 函数赋值给变量
def hello():
    print("Hello Python")

f = hello
f()

# 2. 函数作为返回值
def outer():
    def inner():
        print("内部函数执行")
    return inner

res = outer()
res()

def outer(num):
    # 外层局部变量
    def inner():
        # 内层引用外层变量
        print(f"传入数值：{num}")
    return inner

# 接收内层函数
func = outer(100)
# 调用内层函数
func()

def count_factory():
    cnt = 0
    def counter():
        nonlocal cnt
        cnt += 1
        print(f"当前计数：{cnt}")
    return counter

c1 = count_factory()
c1()  # 1
c1()  # 2
c1()  # 3

import time

def timer_decorator(func):
    # 通用装饰器，接收任意参数
    def wrapper(*args, **kwargs):
        start = time.time()
        # 执行原函数
        res = func(*args, **kwargs)
        end = time.time()
        print(f"函数【{func.__name__}】执行耗时：{end - start:.4f}s")
        # 返回原函数结果
        return res
    return wrapper

# 测试函数
@timer_decorator
def calc_sum(n):
    s = 0
    for i in range(n):
        s += i
    return s

calc_sum(100000)

import time
from functools import wraps

def timer_decorator(func):
    @wraps(func)
    def wrapper(*args, **kwargs):
        start = time.time()
        res = func(*args, **kwargs)
        end = time.time()
        print(f"函数【{func.__name__}】执行耗时：{end - start:.4f}s")
        return res
    return wrapper

from functools import wraps

def log_decorator(switch=True):
    # 外层接收装饰器参数
    def decorator(func):
        @wraps(func)
        def wrapper(*args, **kwargs):
            if switch:
                print(f"【日志】函数{func.__name__}开始执行")
            res = func(*args, **kwargs)
            return res
        return wrapper
    return decorator

# 开启日志
@log_decorator(switch=True)
def test_func():
    print("业务逻辑执行")

test_func()

from functools import wraps

def deco1(func):
    @wraps(func)
    def wrapper():
        print("deco1 前置")
        func()
        print("deco1 后置")
    return wrapper

def deco2(func):
    @wraps(func)
    def wrapper():
        print("deco2 前置")
        func()
        print("deco2 后置")
    return wrapper

@deco1
@deco2
def hello():
    print("核心业务执行")

hello()

from functools import wraps

def login_auth(func):
    @wraps(func)
    def wrapper(user_token, *args, **kwargs):
        # 模拟鉴权逻辑
        if not user_token:
            return {"code": 401, "msg": "未登录，权限不足"}
        return func(user_token, *args, **kwargs)
    return wrapper

# 模拟接口
@login_auth
def get_user_info(token):
    return {"code": 200, "data": "用户信息数据"}

print(get_user_info(""))

from functools import wraps

def cache_decorator(func):
    cache = {}
    @wraps(func)
    def wrapper(*args):
        if args not in cache:
            cache[args] = func(*args)
        return cache[args]
    return wrapper

@cache_decorator
def fib(n):
    if n <= 2:
        return 1
    return fib(n-1) + fib(n-2)

print(fib(30))  # 首次计算，后续直接读取缓存

from functools import wraps

def exception_catch(func):
    @wraps(func)
    def wrapper(*args, **kwargs):
        try:
            return func(*args, **kwargs)
        except Exception as e:
            print(f"【函数异常】{func.__name__}执行失败：{str(e)}")
            return None
    return wrapper

@exception_catch
def divide(a, b):
    return a / b

divide(10, 0)