logger.Exception

Question

在上下文管理器

logger.exception

期间如何调用

__exit__

？

我的上下文管理器类定义是：

import logging
from types import TracebackType
from typing import Optional, Type


class B(A):

    def __init__(self):
        super().__init__()
        self.log = logging.getLogger("B")

    def __exit__(
        self,
        exc_type: Optional[Type[BaseException]],
        exc_inst: Optional[BaseException],
        exc_tb: Optional[TracebackType],
    ) -> bool:
        if exc_inst is not None:
            self.log.exception("EXCEPTION!")
            return False  # let exception propagate
        return True

我是否需要显式地将参数传递给

self.log.exception

，以便它打印异常信息和回溯？

Answer 1

不，您不必显式地将异常详细信息传递给

log.exception

，它会自动拾取它们。

Answer 2

logger.exception

不需要特殊参数；只需拨打

self.log.exception("EXCEPTION!")

即可。

import logging
from types import TracebackType
from typing import Optional, Type


class B:
    def __init__(self):
        super().__init__()
        self.log = logging.getLogger("B")
        self.log.info("Init B")

    def __enter__(self):
        self.log.info("Entering B")
        return self

    def __exit__(
        self,
        exc_type: Optional[Type[BaseException]],
        exc_inst: Optional[BaseException],
        exc_tb: Optional[TracebackType],
    ) -> bool:
        self.log.info("Exiting B")
        if exc_inst is not None:
            self.log.exception("EXCEPTION!")
            # return False  # let exception propagate
        return True


def main():
    with B() as _:
        print("no exception")

    with B() as _:
        raise RuntimeError("BLARG!!!!!")


if __name__ == "__main__":
    logging.basicConfig(level=logging.DEBUG)
    main()

打印

INFO:B:Init B
INFO:B:Entering B
no exception
INFO:B:Exiting B
INFO:B:Init B
INFO:B:Entering B
INFO:B:Exiting B
ERROR:B:EXCEPTION!
Traceback (most recent call last):
  File ".\try1.py", line 34, in main
    raise RuntimeError("BLARG!!!!!")
RuntimeError: BLARG!!!!!

如果

return False

从

__exit__

发生，则外部异常处理程序可能会再次打印异常。