异常处理与调试

try:
    result = 10 / 0
except ZeroDivisionError:
    print("除数不能为零")

try:
    result = 10 / 0
except ZeroDivisionError as e:
    print(f"错误类型: {type(e).__name__}")
    print(f"错误信息: {e}")

try:
    num = int(input("输入一个数字: "))
    result = 10 / num
except ValueError:
    print("请输入有效的整数")
except ZeroDivisionError:
    print("除数不能为零")

try:
    num = int("abc")
    result = 10 / num
except (ValueError, ZeroDivisionError) as e:
    print(f"错误: {e}")

try:
    num = int("42")
except ValueError:
    print("转换失败")
else:
    print(f"成功转换: {num}")  # 只有没有异常时才执行

try:
    file = open("data.txt", "r")
    content = file.read()
except FileNotFoundError:
    print("文件不存在")
else:
    print(content)
finally:
    # 无论成功还是失败，都关闭文件
    if 'file' in locals() and not file.closed:
        file.close()
        print("文件已关闭")

def inner():
    raise ValueError("内部错误")

def middle():
    inner()  # 异常在这里不做处理，继续向上传播

def outer():
    try:
        middle()
    except ValueError as e:
        print(f"捕获到异常: {e}")
        raise  # 重新抛出异常

outer()
# 输出: 捕获到异常: 内部错误
# 异常继续向上传播（如果 outer 也没有捕获）

class ValidationError(Exception):
    """验证错误异常"""
    def __init__(self, field: str, message: str):
        self.field = field
        self.message = message
        super().__init__(f"{field}: {message}")

class PositiveNumberError(ValidationError):
    """要求正数但传入负数或零时的错误"""
    pass


def divide(a, b):
    if b <= 0:
        raise PositiveNumberError("除数", "必须为正数")
    return a / b

try:
    result = divide(10, -1)
except PositiveNumberError as e:
    print(f"验证失败: {e}")
    print(f"字段: {e.field}, 原因: {e.message}")

import traceback

try:
    1 / 0
except Exception:
    traceback.print_exc()  # 打印到标准错误

try:
    1 / 0
except Exception:
    import sys
    exc_type, exc_value, exc_tb = sys.exc_info()

    print("异常类型:", exc_type.__name__)
    print("异常信息:", exc_value)
    print("发生位置:", exc_tb.tb_frame.f_code.co_filename, "第", exc_tb.tb_lineno, "行")

import traceback

try:
    raise ValueError("测试错误")
except ValueError:
    tb = traceback.format_exc()
    print(tb)
    # Traceback (most recent call last):
    #   File "...", line X, in <module>
    #     raise ValueError("测试错误")
    # ValueError: 测试错误

    # 也可以用 format_exception
    import sys
    exc_info = sys.exc_info()
    formatted = traceback.format_exception(*exc_info)
    print("".join(formatted))

import logging

# 配置日志
logging.basicConfig(
    level=logging.DEBUG,              # 记录级别
    format="%(asctime)s [%(levelname)s] %(name)s: %(message)s",
    datefmt="%Y-%m-%d %H:%M:%S"
)

logger = logging.getLogger(__name__)

logger.debug("调试信息")
logger.info("普通信息")
logger.warning("警告信息")
logger.error("错误信息")
logger.critical("严重错误")

import logging

logging.basicConfig(
    level=logging.INFO,
    filename="app.log",        # 输出到文件
    filemode="a",              # 追加模式
    format="%(asctime)s [%(levelname)s] %(message)s"
)

logger = logging.getLogger(__name__)
logger.info("这条消息会写入 app.log")

import logging

# 根 logger
logging.basicConfig(level=logging.INFO)

# 子 logger（推荐方式）
app_logger = logging.getLogger("myapp")
db_logger = logging.getLogger("myapp.database")

app_logger.info("应用启动")
db_logger.info("连接数据库")
# 输出时会带上 logger 名称：myapp: 应用启动
#                   myapp.database: 连接数据库

def factorial(n: int) -> int:
    assert n >= 0, "n 必须为非负整数"
    if n == 0:
        return 1
    return n * factorial(n - 1)

print(factorial(5))  # 120
# print(factorial(-1))  # AssertionError: n 必须为非负整数

import pdb

def divide(a, b):
    pdb.set_trace()  # 程序在此暂停，进入调试模式
    return a / b

divide(10, 2)

def process(data):
    breakpoint()  # 等价于 pdb.set_trace()
    return [x * 2 for x in data]