How to source or activate a virtual environment within an IPython shell?

user_14333379 0
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I use IPython and the %bookmark magic command but the limitation is that I need to exit the IPython shell to activate a virtual environment and then relaunch IPython.

Is there a way, built into IPython, a third-party package, or a known hack to let me activate the environment without exiting the IPython shell?

Actual workflow

# within ipython shell
exit

# bash shell
cd path/of/my/project
poetry shell  # or pipenv shell
ipython

Intended workflow

%cd -b demographics

# activate venv 

import package # from that env
pipenv python-poetry ipython virtualenv python
2 Answers

This is a good question, but unfortunately, the answer might not be what you are hoping for. If I understood your question correctly - this is not possible. Because virtual shell activation is essentially running child process that setups PATH for another Python interpreter and then PYTHONPATH environment variable for this. A child process can never modify its parent process in any operating system. You cannot, for example, change the Python interpreter you already have running because replacing a running process in-memory is super complicated and never done in practice.

If this is a workflow issue and you definitely want to do this from within IPython, I suggest you write an one-liner copy paste command that would do something along these lines:

  • Launches a new IPython using the virtualenv e.g. (source venv/bin/activate && ipython)
  • Terminates the old, existing IPython session that has been launched from the virtualenv (though not sure how you can exit IPython within IPython prompt)

There is likely a better solution for his workflow question. Maybe there is a workflow that is similar as %%bookmark, but for the whole Python environments and processes, like creating shell scripts.

user_3151680

You can workaround and essentially activate the virtualenv from python. This hack is dependent on the location of activate_this.py I've tested it on virtualenv version 20.2.1, might not work with different versions.

Not recommended for Production

Try this:

import virtualenv
import os
import sys

# Provide the location of your venv
venv_loc = r'C:\work\test-venv'

# Setup a new virtual env, if not setup already.
# Skip this line if you want to use an existing virtual env
virtualenv.run.cli_run([venv_loc])

# Find activator script. This is only tested in virtualenv version 20.2.1
if str(os.name).lower() == "nt":
    venv_activator = os.path.join(venv_loc, 'Scripts', 'activate_this.py')
elif str(os.name).lower() == "posix":
    venv_activator = os.path.join(venv_loc, 'bin', 'activate_this.py')
else:
    print("unsupported OS")
    sys.exit(1)

# Activate virtual env
exec(open(venv_activator).read(), {'__file__': venv_activator})

# Now you can import your package.
user_31141790
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