IPython config snippet that makes it work with virtualenv

ipython_config.py

# Configuration snippet to let system-wide IPython work with virtualenvs
# Code taken from Ahmed Soliman's post at:
#   (http://www.ahmedsoliman.com/2011/09/27/use-virtualenv-with-ipython-0-11/)
# Tweaked by Rami Chowdhury
from os import environ
from os.path import join, sep
from sys import version_info

if version_info[0] > 2:
    # Python 3.x doesn't define this, so for convenience, we do.
    def execfile(fname, global_vars):
        with open(fname) as fh:
            exec(compile(fh.read(), fname, "exec"), global_vars)

if 'VIRTUAL_ENV' in environ:
    # OK, we're running in a virtualenv - run virtualenv's own activation
    # script to set it up just as if we were using the environment's Python
    virtual_env_dir = environ['VIRTUAL_ENV']
    activate_this = join(virtual_env_dir, "bin", "activate_this.py")
    execfile(activate_this, dict(__file__=activate_this))
    # At this point everything should be set up, so just print an informative
    # message, and optionally change the IPython prompt, and we're done
    virtual_env_name = virtual_env_dir.split(sep)[-1]
    message = '[using virtualenv "{0}" ({1})]'.format(virtual_env_name,
                                                      virtual_env_dir)
    print(message)
    # If you don't want to change your IPython prompt to match your virtualenv
    # (the way your shell prompt changes), then comment this bit out.
    conf = get_config()
    conf.PromptManager.in_template = virtual_env_name + " [\\#]: "
    del virtual_env_dir
del environ, join, sep, version_info