runfromvenv.py

import venv, sys, inspect
from subprocess import check_call, getoutput
from os.path import realpath, dirname, join, basename, isdir, splitext
from os import environ, execvp

frame = next(reversed(inspect.stack())).frame
project_main_file = realpath(frame.f_globals["__file__"])
project_dir = dirname(project_main_file)
project_name = splitext(basename(project_main_file))[0]
venv_dir = join(project_dir, "." + project_name + ".venv")

if "VIRTUAL_ENV" != venv_dir:
    if not isdir(venv_dir):
        environ["P"] = "PATH"  # random value but reusing already aliased value
        # system_site_packages=False, clear=False, symlinks=False, upgrade=False, with_pip=False, prompt=None, upgrade_deps=False
        venv.create(venv_dir, with_pip=True)

    venv_bin_dir = join(venv_dir, "bin")
    e = realpath(sys.executable)

    if e != realpath(join(venv_bin_dir, basename(e))):
        environ.update(
            {
                "VIRTUAL_ENV": venv_dir,
                "PATH": venv_bin_dir + ":" + environ["PATH"],
            }
        )
        execvp(project_main_file, sys.argv)

    deps = frame.f_locals["deps"]
    [
        check_call(["pip", "install", *args])
        for args in (("--upgrade", "pip", "setuptools", "wheel"), deps)
        if "P" in environ
    ]

    [getoutput("pip install " + dep) for dep in deps if "P" in environ]