高阶函数与包装器函数

1def add(a, b):
2    return a + b
3
4def subtract(a, b):
5    return a - b
6
7def multiply(a, b):
8    return a * b
9
10# 将函数存储在字典中
11operations = {
12    "plus": add,
13    "minus": subtract,
14    "times": multiply
15}
16
17selected_op = "minus"
18
19# 获取函数对象并立即调用
20result = operations[selected_op](10, 4)
21
22print(f"Operation: {selected_op}, Result: {result}")

1def apply_to_list(data, strategy_func):
2    """对列表中的每个元素应用策略函数。"""
3    results = []
4    for item in data:
5        transformed = strategy_func(item)
6        results.append(transformed)
7    return results
8
9def square(x):
10    return x * x
11
12def stringify(x):
13    return f"Value: {x}"
14
15numbers = [1, 2, 3, 4]
16
17# 将 'square' 函数作为参数传递
18squared_nums = apply_to_list(numbers, square)
19
20# 将 'stringify' 函数作为参数传递
21string_nums = apply_to_list(numbers, stringify)
22
23print(f"Squared: {squared_nums}")
24print(f"Strings: {string_nums}")

1def power_factory(exponent):
2    """返回一个新函数，将数字提升到指定的指数。"""
3    
4    def inner_power(base):
5        # 'exponent' 从外部作用域捕获
6        return base ** exponent
7    
8    return inner_power
9
10# 创建一个专门用于平方的函数
11square_it = power_factory(2)
12
13# 创建一个专门用于立方的函数
14cube_it = power_factory(3)
15
16print(f"5 squared is: {square_it(5)}")
17print(f"5 cubed is: {cube_it(5)}")

1def logger_wrapper(target_func):
2    """包装一个函数，在执行前添加日志记录。"""
3    
4    def inner_wrapper(x, y):
5        print(f"[LOG] 调用函数 '{target_func.__name__}'，输入为 {x}, {y}")
6        # 调用原始函数
7        result = target_func(x, y)
8        print(f"[LOG] 执行完成。结果: {result}")
9        return result
10    
11    return inner_wrapper
12
13def add(a, b):
14    return a + b
15
16# 手动包装 'add' 函数
17add_with_logging = logger_wrapper(add)
18
19# 调用包装后的版本
20final_sum = add_with_logging(5, 7)

1def logger_wrapper(target_func):
2    def inner_wrapper(x, y):
3        return target_func(x, y)
4    return inner_wrapper
5
6def multiply(a, b):
7    """将两个数字相乘。"""
8    return a * b
9
10print(f"原始名称: {multiply.__name__}")
11
12# 包装函数
13multiply = logger_wrapper(multiply)
14
15print(f"包装后名称: {multiply.__name__}")
16print(f"包装后文档字符串: {multiply.__doc__}")