Python custom traceback

custom_traceback_example.py

import linecache
import re
import sys
from types import TracebackType
from typing import Any, Optional

PACKAGE_PATH_PATTERN = r'.*/lib/python.*/site-packages/.*'


class TracebackLogger:

    @staticmethod
    def _print_variables(variables: dict[str, Any]) -> None:
        """Prints scoped variables contents without dunder keys."""
        for k, v in variables.items():
            if not (k.startswith('__') and k.endswith('__')):
                print(k, ':', v)

    @staticmethod
    def _print_exception(
        exception_type: Optional[type],
        exception_value: Optional[BaseException],
        traceback: Optional[TracebackType]
    ) -> None:
        """Format and print exceptions."""
        local_vars = {}
        global_vars = {}
        function_name_local = ''
        if exception_type is not None:
            print('\n--- exception ----\n')
            print(f'{exception_type.__name__}: {exception_value}')
        else:
            print(f'{exception_type}: {exception_value}')
        print('\n--- traceback ----\n')
        while traceback:
            filename = traceback.tb_frame.f_code.co_filename
            function_name = traceback.tb_frame.f_code.co_name
            line_no = traceback.tb_lineno
            line = linecache.getline(filename, line_no).strip()
            print(f'File: "{filename}", line {line_no}, in {function_name}')
            print('\t', line)
            if not re.match(PACKAGE_PATH_PATTERN, filename):
                function_name_local = function_name
                local_vars = traceback.tb_frame.f_locals
                global_vars = traceback.tb_frame.f_globals
            traceback = traceback.tb_next
        print(f'\n--- local variables for {function_name_local} ----\n')
        TracebackLogger._print_variables(local_vars)
        print(f'\n--- global varables for {function_name_local} ----\n')
        TracebackLogger._print_variables(global_vars)

    @staticmethod
    def traceback_hook(
        exception_type: Optional[type],
        exception_value: Optional[BaseException],
        traceback: Optional[TracebackType]
    ) -> None:
        """Replacement for system exception hook."""
        if traceback:
            TracebackLogger._print_exception(
                exception_type, exception_value, traceback)

    @staticmethod
    def init_custom_traceback():
        sys.excepthook = TracebackLogger.traceback_hook

# exception code ends here


def failing_function(data: list[Any], num: int) -> None:
    """Failing function."""
    local_var = 100  # <-- locals
    for n in range(num):
        data[n]


def main() -> None:
    failing_function(DATA, NUM)


if __name__ == '__main__':

    TracebackLogger.init_custom_traceback()  # <-- initialize hook
    # globals
    NUM = 12
    DATA = list(range(5))
    main()