Opening an IPython shell on any (uncaught) exception

Question

I have defined the following (embedded) shell in Python:

from IPython.config.loader import Config
cfg = Config()
prompt_config = cfg.PromptManager
prompt_con         


        

Answer 1

I think it's hardly possible to let the exception pass all the way through the call stack to find out whether or not someone would catch and handle it in the end, and then return to the scope where it was first raised. That original scope is gone, when the exception popped out of it.

Your best bet may be to wrap all the parts where you want your shell to come up to handle an exception with a dedicated try ... except block, as in the following:

try: 
   pass # stuff that may raise an exception
except KeyboardInterrupt:
   # some exception you want to handle
   raise 
except SystemExit:
   # another exception you want to handle
   raise 
except: 
   # get a hand on any unhandled exception
   ipshell(traceback.format_exc())

(Not sure if this can be implemented more elegantly. I'd be very interested in a better solution as well!)

Answer 2

Defining the following in my ipython shell seems to do what you want:

def custom_exc(shell, etype, evalue, tb, tb_offset=None):
    shell.showtraceback((etype, evalue, tb), tb_offset=tb_offset)
    ipshell()

get_ipython().set_custom_exc((Exception,), custom_exc)