Python 新手必看：10个渐进式开源项目助你快速入门到进阶

# 简化版 todo.py 结构
def main():
    parser = argparse.ArgumentParser()
    subparsers = parser.add_subparsers()
    
    add_parser = subparsers.add_parser("add")
    add_parser.add_argument("text")
    
    # ... list, done 子命令
    
    args = parser.parse_args()
    # 根据 args.command 分发处理

import re
from collections import Counter

LOG_PATTERN = re.compile(
    r'(?P<ip>\S+) \S+ \S+ \[(?P<time>[^\]]+)\] '
    r'"(?P<method>\S+) (?P<path>\S+) \S+" '
    r'(?P<status>\d{3})'
)

def analyze_log(filepath):
    ips = Counter()
    statuses = Counter()
    paths = Counter()
    
    with open(filepath) as f:
        for line in f:
            m = LOG_PATTERN.match(line)
            if m:
                d = m.groupdict()
                ips[d['ip']] += 1
                statuses[d['status']] += 1
                paths[d['path']] += 1
    
    return {
        'top_ips': ips.most_common(10),
        'status_counts': dict(statuses),
        'top_paths': paths.most_common(10),
    }

import string

BASE62 = string.ascii_letters + string.digits  # a-zA-Z0-9

def encode_base62(num):
    """将整数转为 Base62 字符串"""
    if num == 0:
        return BASE62[0]
    result = []
    while num:
        num, rem = divmod(num, 62)
        result.append(BASE62[rem])
    return ''.join(reversed(result))

def decode_base62(s):
    """将 Base62 字符串转回整数"""
    return sum(BASE62.index(c) * (62 ** i) for i, c in enumerate(reversed(s)))

import requests
from bs4 import BeautifulSoup
import time
import csv

def fetch_douban_top250():
    base_url = "https://movie.douban.com/top250"
    headers = {
        "User-Agent": "Mozilla/5.0 (compatible; Bot/1.0)"
    }
    
    movies = []
    for start in range(0, 250, 25):
        resp = requests.get(f"{base_url}?start={start}", headers=headers)
        soup = BeautifulSoup(resp.text, "html.parser")
        
        for item in soup.select(".item"):
            title = item.select_one(".title").text
            rating = item.select_one(".rating_num").text
            movies.append({"title": title, "rating": float(rating)})
        
        time.sleep(1)   # 礼貌爬虫，不要请求太快
    
    return movies

# 1. 克隆代码
git clone https://github.com/pallets/flask.git
cd flask

# 2. 找到入口
# src/flask/__init__.py → 看 exports
# src/flask/app.py → Flask 类

# 3. 追踪一个请求
# Flask.wsgi_app() → request_context() → dispatch_request()

# 1. Fork 项目到你账号
# 2. 克隆你的 Fork
git clone https://github.com/YOUR_NAME/project.git

# 3. 创建分支
git checkout -b fix-typo-readme

# 4. 修改代码
# ...

# 5. 提交
git add .
git commit -m "docs: fix typo in README.md"
git push origin fix-typo-readme

# 6. 在 GitHub 上发起 Pull Request