#!/usr/bin/env python
# cardinal_pythonlib/exceptions.py
"""
===============================================================================
Original code copyright (C) 2009-2022 Rudolf Cardinal (rudolf@pobox.com).
This file is part of cardinal_pythonlib.
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
https://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
===============================================================================
**Functions for exception handling.**
"""
import sys
import traceback
from typing import Dict, NoReturn
from cardinal_pythonlib.logs import get_brace_style_log_with_null_handler
log = get_brace_style_log_with_null_handler(__name__)
# =============================================================================
# Exception handling
# =============================================================================
[docs]def add_info_to_exception(err: Exception, info: Dict) -> None:
"""
Adds an information dictionary to an exception.
See
https://stackoverflow.com/questions/9157210/how-do-i-raise-the-same-exception-with-a-custom-message-in-python
Args:
err: the exception to be modified
info: the information to add
""" # noqa
if not err.args:
err.args = ("",)
err.args += (info,)
[docs]def recover_info_from_exception(err: Exception) -> Dict:
"""
Retrives the information added to an exception by
:func:`add_info_to_exception`.
"""
if len(err.args) < 1:
return {}
info = err.args[-1]
if not isinstance(info, dict):
return {}
return info
[docs]def die(exc: Exception = None, exit_code: int = 1) -> NoReturn:
"""
It is not clear that Python guarantees to exit with a non-zero exit code
(errorlevel in DOS/Windows) upon an unhandled exception. So this function
produces the usual stack trace then dies with the specified exit code.
See
https://stackoverflow.com/questions/9555133/e-printstacktrace-equivalent-in-python.
Test code:
.. code-block:: python
import logging
import sys
import traceback
logging.basicConfig(level=logging.DEBUG)
log = logging.getLogger()
def fail():
try:
x = 1/0
except Exception as exc:
die(exc)
Then call
.. code-block:: python
fail()
... which should exit Python; then from Linux (for example):
.. code-block:: bash
echo $? # show exit code
""" # noqa
if exc:
lines = traceback.format_exception(
None, exc, exc.__traceback__ # etype: ignored
) # https://www.python.org/dev/peps/pep-3134/
msg = "".join(lines)
# Method 1:
# print("".join(lines), file=sys.stderr, flush=True)
# Method 2:
log.critical("{}", msg)
log.critical("Exiting with exit code {}", exit_code)
sys.exit(exit_code)