Python 装饰器

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装饰器可以在不修改函数源码的情况下给函数增加额外功能，常用于日志、性能统计、权限校验。

基本装饰器

def log(func):
    def wrapper(*args, **kwargs):
        print(f"调用函数: {func.__name__}")
        result = func(*args, **kwargs)
        print(f"函数返回: {result}")
        return result
    return wrapper

@log
def add(a, b):
    return a + b

add(3, 5)

带参数的装饰器

def repeat(n):
    def decorator(func):
        def wrapper(*args, **kwargs):
            for _ in range(n):
                func(*args, **kwargs)
        return wrapper
    return decorator

@repeat(3)
def say_hello(name):
    print(f"你好, {name}!")

实际应用：计时器

import time
from functools import wraps

def timer(func):
    @wraps(func)
    def wrapper(*args, **kwargs):
        start = time.perf_counter()
        result = func(*args, **kwargs)
        duration = time.perf_counter() - start
        print(f"{func.__name__} 耗时: {duration:.4f}秒")
        return result
    return wrapper

@timer
def slow_function():
    time.sleep(1)
    return "完成"