workon.sh

#!/usr/bin/env bash
# This script must be sourced from within a shell
# and not executed. For instance with:
# 
#   . path/to/script/workon.sh

function workon() {

  curdir=${PWD##*/}          # to assign to a variable
  curdir=${curdir:-/}        # to correct for the case where PWD=/

  parent=$(dirname $PWD)
  parent=${parent##*/}
  parent=${parent:-/}

  combo="${parent}_${curdir}"

  venv_path="${HOME}/virtualenvs/${combo}"

  if [ ! -z ${VIRTUAL_ENV+x} ] ; then
    deactivate
  fi

  if [ ! -d "${venv_path}" ]; then
    python3.9 -m venv "${venv_path}"
  fi

  source "${venv_path}/bin/activate"
}