Python学习——装饰器（一）：两个简单例子

例一 计时器

#创建一个装饰器，用于计算函数执行时间
import time

def time_this(func):
    def wrapper(*args, **kwargs):
        start_time = time.time()
        result = func(*args, **kwargs)
        end_time = time.time()
        execution_time = end_time - start_time
        print(f"Execution time of {func.__name__}: {execution_time:.6f} seconds")
        return result
    return wrapper

# 被装饰的函数
@time_this
def expensive_function(n):
    result = 0
    for i in range(n):
        result += i * i
        time.sleep(0.001)  # 模拟执行时间
        # print(f"Processing {i+1}/{n}...")
        if i % 1000 == 0:
            print("Progress: {:.2%}".format(i / n))
            time.sleep(0.01)  # 模拟进度
            print("Progress updated...")
        if i % 5000 == 0:
            print("Saving intermediate result...")
            time.sleep(0.1)  # 模拟中断
            print("Saving completed...")
        if i % 10000 == 0:
            print("Releasing resources...")
            time.sleep(0.2)  # 模拟释放资源
            print("Resources released...")
    return result

# 调用被装装饰的函数
expensive_function(10000)
            

例二 类型检查器

# 创建一个装饰器，用于检查函数的参数是否符合预期类型
def check_types(*expected_types):
    def decorator(func):
        def wrapper(*args, **kwargs):
            for i, arg in enumerate(args):
                if not isinstance(arg, expected_types[i]):
                    raise TypeError(f"Expected {expected_types[i]} for argument {i+1}, got {type(arg).__name__}")
            for key, value in kwargs.items():
                if not isinstance(value, expected_types[i+len(args)]):
                    raise TypeError(f"Expected {expected_types[i+len(args)]} for argument {key}, got {type(value).__name__}")
            return func(*args, **kwargs)
        return wrapper
    return decorator

# 示例使用

@check_types(int, str, list)
def my_function(num, name, items):
    print(f"Number: {num}, Name: {name}, Items: {items}")

my_function(10, "John", ["apple", "banana"])  # 符合预期类型

my_function(10, "John", 123)  # 类型不匹配，会抛出 TypeError