Launch an IPython shell on exception

Question

Is there a way to launch an IPython shell or prompt when my program runs a line that raises an exception?

I\'m mostly interested in the context, variables, in the sc

Answer 1

@snapshoe's answer does not work on newer versions of IPython.

This does however:

import sys 
from IPython import embed

def excepthook(type, value, traceback):
    embed()

sys.excepthook = excepthook

Answer 2

Update for IPython v0.13:

import sys
from IPython.core import ultratb
sys.excepthook = ultratb.FormattedTB(mode='Verbose',
     color_scheme='Linux', call_pdb=1)

Answer 3

Do you actually want to open a pdb session at every exception point? (as I think a pdb session opened from ipython is the same as the one open in the normal shell). If that's the case, here's the trick: http://code.activestate.com/recipes/65287-automatically-start-the-debugger-on-an-exception/

Answer 4

If you want to both get the traceback and open a IPython shell with the environment at the point of the exception:

def exceptHook(*args):
    '''A routine to be called when an exception occurs. It prints the traceback
    with fancy formatting and then calls an IPython shell with the environment
    of the exception location.
    '''
    from IPython.core import ultratb
    ultratb.FormattedTB(call_pdb=False,color_scheme='LightBG')(*args)
    from IPython.terminal.embed import InteractiveShellEmbed
    import inspect
    frame = inspect.getinnerframes(args[2])[-1][0]
    msg   = 'Entering IPython console at {0.f_code.co_filename} at line {0.f_lineno}'.format(frame)
    savehook = sys.excepthook # save the exception hook
    InteractiveShellEmbed()(msg,local_ns=frame.f_locals,global_ns=frame.f_globals)
    sys.excepthook = savehook # reset IPython's change to the exception hook

import sys
sys.excepthook = exceptHook

Note that it is necessary to pull than namespace information from the last frame referenced by the traceback (arg[2])