Adding function to sys.excepthook

Question

Say I have something like this, which sends unhanded exceptions to logging.critical():

import sys

def register_handler():
    orig_excepthook =         


        

Answer 1

If you make orig_excepthook an argument with a default value, the default value is fixed once at definition-time. So repeated calls to register_handler will not change orig_excepthook.

import sys

def register_handler(orig_excepthook=sys.excepthook):
    def error_catcher(*exc_info):
        import logging
        log = logging.getLogger(__name__)
        log.critical("Unhandled exception", exc_info=exc_info)
        orig_excepthook(*exc_info)
    sys.excepthook = error_catcher

---

import logging
logging.basicConfig()

register_handler()
register_handler()
register_handler()

undefined() 

produces only one call to log.critical.