Python 装饰器完全指南

深入理解 Python 装饰器，学习如何编写优雅的装饰器。

#Python #后端 #教程

Python 装饰器完全指南

装饰器是 Python 中强大的语法糖。

什么是装饰器？

装饰器是一个函数，它接受另一个函数并扩展其行为。

def simple_decorator(func):
    def wrapper():
        print("Before function call")
        func()
        print("After function call")
    return wrapper


@simple_decorator
def say_hello():
    print("Hello!")


say_hello()

带参数的装饰器

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


@repeat(times=3)
def greet(name):
    print(f"Hello, {name}!")


greet("World")

保留函数元信息

import functools


def decorator(func):
    @functools.wraps(func)
    def wrapper(*args, **kwargs):
        return func(*args, **kwargs)
    return wrapper

类装饰器

class CountCalls:
    def __init__(self, func):
        functools.update_wrapper(self, func)
        self.func = func
        self.count = 0


    def __call__(self, *args, **kwargs):
        self.count += 1
        print(f"Call {self.count} of {self.func.__name__}")
        return self.func(*args, **kwargs)


@CountCalls
def fibonacci(n):
    if n < 2:
        return n
    return fibonacci(n - 1) + fibonacci(n - 2)

实际应用：性能监控

import time


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


@timer
def expensive_operation():
    time.sleep(1)
    return "Done"

装饰器让代码更优雅！

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