Launch ipython shell from python script that uses command line option parsing

I've been looking around for quite some time to find a way to optimally do this but haven't been successful. My problem setting is as follows:

I want to be able to launch an ipython shell for debugging purposes from within a python script that uses command line option parsing (optparse), in a non-programmatic fashion.

To illustrate the issue, I have some example code bellow:

import sys
from optparse import OptionParser

class toolRunner(object):

    def __init__(self):
        self._parseOptions()

    def _parseOptions(self):
        usage = "Usage: %prog [--help] [options] input.cmp.h5" 
        parser = OptionParser(usage=usage)
        parser.add_option('-r', type='string', dest='ins', default='1,2,3,4')
        self.opts, args = parser.parse_args()

    def main(self):
        print testSum(self.opts.ins)

def testSum(dstr):
    from IPython.Shell import IPShellEmbed; IPShellEmbed()()
    return sum(map(int,dstr.strip().split(',')))

if __name__ == '__main__':
    sys.exit(toolRunner().main())

If I now call my test script test.py as follows:

python test.py -r 1,2,3,4

I get the following error:

WARNING:
Error in Arguments: "Ambiguous option '-r';  matches ['readline', 'readline_merge_completions', 'readline_omit__names', 'rcfile']"

I guess ipython is trying to interpret the commandline option -r as being destined for it. If I instead call the testSum(dstr) function programmatically, then no such error is generated and I get an ipython shell to pop up. That is, if I substitute the following code in the above example:

if __name__ == '__main__':
    # sys.exit(toolRunner().main())
    testSum('1,2,3,4')

And run my script as:

python test.py -r 1,2,3,4

all runs well.

I have already 开发者_开发问答looked into alternatives i.e. using ipdb (Is it possible to go into ipython from code?), but would prefer doing it the way I am suggesting here due to the richness of features I get from the ipython shell as well as because it would be nice to know why my way doesn't work.

[Reposting as an answer since it worked]

Try specifying argv, like so: IPShellEmbed(argv=[])(). That should stop IPython from looking at the arguments you gave to your script.