在Python中，装饰器是一种高级功能，用于修改或增强函数或方法的行为。通过使用装饰器，我们可以将一段代码捆绑到另一个函数或方法上，以添加额外的功能或修改其行为。装饰器本质上是一个接受函数对象作为参数的可调用对象，并返回一个新的函数对象。
在Python中，装饰器使用@语法糖来定义。下面是一个简单的装饰器示例：
pythondef my_decorator(func):
def wrapper():
print("Something is happening before the function is called.")
func()
print("Something is happening after the function is called.")
return wrapper
@my_decorator
def say_hello():
print("Hello!")
say_hello()
def my_decorator(func):
def wrapper():
print("Something is happening before the function is called.")
func()
print("Something is happening after the function is called.")
return wrapper
@my_decorator
def say_hello():
print("Hello!")
say_hello()在这个例子中，我们定义了一个名为my_decorator的装饰器。当将其应用到say_hello函数时，该装饰器会在调用say_hello函数之前和之后分别输出一条消息。最后，当我们调用say_hello函数时，它会输出这三条消息。
下面是一个更复杂的例子，展示如何使用装饰器来记录函数执行的时间：
pythonimport time
def timer_decorator(func):
def wrapper(*args, **kwargs):
start_time = time.time()
result = func(*args, **kwargs)
end_time = time.time()
print(f"Function '{func.__name__}' took {end_time - start_time:.6f} seconds to execute.")
return result
return wrapper
@timer_decorator
def some_slow_function():
time.sleep(1)
print("The function has finished executing.")
some_slow_function()
import time
def timer_decorator(func):
def wrapper(*args, **kwargs):
start_time = time.time()
result = func(*args, **kwargs)
end_time = time.time()
print(f"Function '{func.__name__}' took {end_time - start_time:.6f} seconds to execute.")
return result
return wrapper
@timer_decorator
def some_slow_function():
time.sleep(1)
print("The function has finished executing.")
some_slow_function()在这个例子中，我们定义了一个名为timer_decorator的装饰器，它会记录some_slow_function函数的执行时间，并在执行结束后输出该时间。我们通过将@timer_decorator应用到some_slow_function函数来使用这个装饰器。当运行some_slow_function函数时，它会输出函数的执行时间。
