Python 最佳实践：编写简洁且可维护的代码

# 不良示例def calculate_total(x,y,z):    return x+y+z# 良好示例def calculate_total(price, tax, shipping):    """计算包含税费和运费的总成本。"""    return price + tax + shipping

from typing import List, Dict, Optionaldef process_user_data(    user_id: int,    settings: Dict[str, str],    tags: Optional[List[str]] = None) -> bool:    """处理用户数据并返回成功状态。"""    if tags is None:        tags = []    # 处理逻辑    return True

# 不良方法file = open('data.txt', 'r')content = file.read()file.close()# 良好方法with open('data.txt', 'r') as file:    content = file.read()    # 文件会在代码块结束后自动关闭

def fetch_user_data(user_id: int) -> Dict:    try:        # 获取用户数据        user = database.get_user(user_id)        return user.to_dict()    except DatabaseConnectionError as e:        logger.error(f"数据库连接失败: {e}")        raise    except UserNotFoundError:        logger.warning(f"用户 {user_id} 未找到")        return {}

# 简单易读 - 良好！squares = [x * x for x in range(10)]# 过于复杂 - 需要拆分# 不良示例result = [x.strip().lower() for x in text.split(',') if x.strip() and not x.startswith('#')]# 更好方法def process_item(item: str) -> str:    return item.strip().lower()def is_valid_item(item: str) -> bool:    item = item.strip()    return bool(item) and not item.startswith('#')result = [process_item(x) for x in text.split(',') if is_valid_item(x)]

from dataclasses import dataclass, fieldfrom datetime import datetime@dataclassclass UserProfile:    username: str    email: str    created_at: datetime = field(default_factory=datetime.now)    is_active: bool = True    def __post_init__(self):        self.email = self.email.lower()

import pytestfrom myapp.calculator import calculate_totaldef test_calculate_total_with_valid_inputs():    result = calculate_total(100, 10, 5)    assert result == 115def test_calculate_total_with_zero_values():    result = calculate_total(100, 0, 0)    assert result == 100def test_calculate_total_with_negative_values():    with pytest.raises(ValueError):        calculate_total(100, -10, 5)