problems exiting from Python using iPython/Spyder

Question

This question has been asked before, but I have tried the solutions in related questions such as this to no avail.

I am having problems with Python's exit command, and I have ruled out a problem with my code as run by vanilla Python 3. The problem comes when I run it with iPython or in Spyder's iPython console.

When I use just a simple exit command, I get the error:

NameError: name 'exit' is not defined

I have already imported sys as suggested by the other link. The only thing that kind of works is to try sys.exit() in which case I get:

An exception has occurred, use %tb to see the full traceback.

SystemExit

C:\Users\sdewey\AppData\Local\Continuum\Anaconda3\lib\site-
packages\IPython\core\interactiveshell.py:2870: UserWarning: To exit: use 
'exit', 'quit', or Ctrl-D.
  warn("To exit: use 'exit', 'quit', or Ctrl-D.", stacklevel=1)

I only say that that "kind of works" because the error message is smaller so it's less annoying :).

Any ideas? Seems like an issue with iPython. I have encountered a different issue in Jupyter (which uses iPython) where quit was ignored entirely, which I posted about separately here

Answer 1

I've run into the same issue while running scripts containing exit() in Pycharm's IPython shell. I learned here, that exit is intended for interactive shells, so behaviour will vary depending on how the shell implements it.

I could figure out a solution which would...

• not kill the kernel on exit
• not display a traceback
• not force you to entrench code with try/excepts
• work with or without IPython, without changes in code

Just import 'exit' from the code beneath into scripts you also intend to run with IPython and calling 'exit()' should work. You can use it in jupyter as well (instead of quit, which is just another name for exit), where it doesn't exit quite as silent as in the IPython shell, by letting you know that...

An exception has occurred, use %tb to see the full traceback.

IpyExit

"""
# ipython_exit.py
Allows exit() to work if script is invoked with IPython without
raising NameError Exception. Keeps kernel alive.

Use: import variable 'exit' in target script with 'from ipython_exit import exit'    
"""

import sys
from io import StringIO
from IPython import get_ipython


class IpyExit(SystemExit):
    """Exit Exception for IPython.

    Exception temporarily redirects stderr to buffer.
    """
    def __init__(self):
        # print("exiting")  # optionally print some message to stdout, too
        # ... or do other stuff before exit
        sys.stderr = StringIO()

    def __del__(self):
        sys.stderr.close()
        sys.stderr = sys.__stderr__  # restore from backup


def ipy_exit():
    raise IpyExit


if get_ipython():    # ...run with IPython
    exit = ipy_exit  # rebind to custom exit
else:
    exit = exit      # just make exit importable