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青海微网站建设,怎样做网站兼职,wordpress分类标签插件,营销型网站建设品牌Python语法糖教程第2天—Python装饰器深度解析与高阶应用指南一、装饰器本质揭秘 1.1 装饰器的运行时序 def decorator(func):print("装饰器初始化阶段")def wrapper(*args, **kwargs):print("函数执行前操作")result func(*args, **kwargs)print(&qu…

Python语法糖教程第2天—Python装饰器深度解析与高阶应用指南

一、装饰器本质揭秘

1.1 装饰器的运行时序

def decorator(func):print("装饰器初始化阶段")def wrapper(*args, **kwargs):print("函数执行前操作")result = func(*args, **kwargs)print("函数执行后操作")return resultreturn wrapper@decorator  # 此处立即执行装饰器函数
def target_function():print("核心业务逻辑")"""
输出：
装饰器初始化阶段
"""

1.2 装饰器等效原理

# @decorator 语法糖等效于
target_function = decorator(target_function)

1.3 装饰器执行流程图

二、装饰器分类体系

2.1 函数装饰器

基础模板：

def simple_decorator(func):def wrapper(*args, **kwargs):# 前置处理result = func(*args, **kwargs)# 后置处理return resultreturn wrapper

2.2 类装饰器

实现原理：

class ClassDecorator:def __init__(self, func):self.func = funcdef __call__(self, *args, **kwargs):print(f"调用 {self.func.__name__}")return self.func(*args, **kwargs)@ClassDecorator
def example():pass

2.3 参数化装饰器

三层嵌套结构：

def repeat(times):def outer_wrapper(func):def inner_wrapper(*args, **kwargs):for _ in range(times):result = func(*args, **kwargs)return resultreturn inner_wrapperreturn outer_wrapper@repeat(3)
def greet(name):print(f"Hello {name}")greet("World")
"""
输出：
Hello World
Hello World
Hello World
"""

三、元编程进阶技巧

3.1 保留元数据

from functools import wrapsdef meta_decorator(func):@wraps(func)  # 保留原始函数信息def wrapper(*args, **kwargs):return func(*args, **kwargs)return wrapper

3.2 装饰器堆叠

@decorator1
@decorator2
@decorator3
def multi_decorated():pass# 等效于 decorator1(decorator2(decorator3(func)))

3.3 装饰器状态保持

def counter_decorator(func):def wrapper(*args, **kwargs):wrapper.calls += 1print(f"第{wrapper.calls}次调用")return func(*args, **kwargs)wrapper.calls = 0return wrapper

四、典型应用场景

4.1 权限控制装饰器

def require_role(role):def decorator(func):@wraps(func)def wrapper(user, *args, **kwargs):if user.role != role:raise PermissionError("权限不足")return func(user, *args, **kwargs)return wrapperreturn decorator@require_role('admin')
def delete_user(user):print(f"删除用户 {user.name}")

4.2 异步函数装饰器

import asynciodef async_timer(func):@wraps(func)async def wrapper(*args, **kwargs):start = time.time()result = await func(*args, **kwargs)print(f"耗时 {time.time()-start:.2f}s")return resultreturn wrapper@async_timer
async def fetch_data():await asyncio.sleep(1)return "数据获取成功"

4.3 类方法装饰器

def class_decorator(method):def wrapper(self, *args, **kwargs):print(f"调用 {self.__class__.__name__} 的方法")return method(self, *args, **kwargs)return wrapperclass MyClass:@class_decoratordef show(self):print("实例方法被调用")

五、调试与优化策略

5.1 调试技巧

import inspectdef debug_decorator(func):@wraps(func)def wrapper(*args, **kwargs):print(f"输入参数: {inspect.signature(func)}")print(f"实际参数: args={args}, kwargs={kwargs}")result = func(*args, **kwargs)print(f"返回结果: {result}")return resultreturn wrapper

5.2 性能优化方案

import time
from functools import lru_cachedef cache_decorator(func):@lru_cache(maxsize=128)@wraps(func)def wrapper(*args, **kwargs):return func(*args, **kwargs)return wrapper@cache_decorator
def heavy_calculation(n):time.sleep(2)return n * n

六、综合实战案例

6.1 实现简易Web框架

class MiniWebFramework:routes = {}@classmethoddef route(cls, path):def decorator(func):cls.routes[path] = funcreturn funcreturn decorator@classmethoddef run(cls):from http.server import BaseHTTPRequestHandler, HTTPServerclass Handler(BaseHTTPRequestHandler):def do_GET(self):if self.path in cls.routes:self.send_response(200)self.end_headers()response = cls.routes[self.path]()self.wfile.write(response.encode())else:self.send_response(404)self.end_headers()server = HTTPServer(('localhost', 8080), Handler)server.serve_forever()@MiniWebFramework.route('/')
def index():return "欢迎来到首页"@MiniWebFramework.route('/about')
def about():return "关于我们页面"MiniWebFramework.run()