Python 从 0 到 1 完整教程

🔴 第四阶段：高级特性与并发编程

目标：理解生成器、装饰器、上下文管理器及异步编程。

1. 三大高级特性

# 装饰器：增强函数功能
import functools
import time

def timer(func):
    @functools.wraps(func)
    def wrapper(*args, **kwargs):
        start = time.perf_counter()
        result = func(*args, **kwargs)
        elapsed = time.perf_counter() - start
        print(f"{func.__name__} 耗时: {elapsed:.4f}s")
        return result
    return wrapper

@timer
def slow_function():
    time.sleep(1)
    return "done"

# 上下文管理器：资源安全释放
from contextlib import contextmanager

@contextmanager
def managed_file(path: str, mode: str):
    f = open(path, mode)
    try:
        yield f
    finally:
        f.close()

# 生成器：惰性求值，节省内存
def read_large_file(path: str):
    with open(path, 'r', encoding='utf-8') as f:
        for line in f:
            yield line.strip()

2. 异步编程 (asyncio)

import asyncio
import aiohttp

async def fetch_url(url: str) -> str:
    async with aiohttp.ClientSession() as session:
        async with session.get(url) as response:
            return await response.text()

async def main():
    urls = ["https://api.example.com/1", "https://api.example.com/2"]
    tasks = [fetch_url(url) for url in urls]
    results = await asyncio.gather(*tasks)
    for r in results:
        print(r[:100])

asyncio.run(main())