Question

Let’s say I want to be able to log to file every time any exception is raised, anywhere in my program. I don’t want to modify any existing code.

Of course, this could be generalized to being able to insert a hook every time an exception is raised.

Would the following code be considered safe for doing such a thing?

class MyException(Exception):

    def my_hook(self):
        print('---> my_hook() was called');

    def __init__(self, *args, **kwargs):
        global BackupException;
        self.my_hook();
        return BackupException.__init__(self, *args, **kwargs);


def main():
    global BackupException;
    global Exception;

    BackupException = Exception;
    Exception = MyException;

    raise Exception('Contrived Exception');


if __name__ == '__main__':
    main();

Answer 1

If you want to log uncaught exceptions, just use sys.excepthook.

I’m not sure I see the value of logging all raised exceptions, since lots of libraries will raise/catch exceptions internally for things you probably won’t care about.