pypa_install.py

#!/usr/bin/env python3.6

from contextlib import suppress
from pathlib import Path, PosixPath
from subprocess import run, PIPE
from sys import exit, argv
from sys import stderr, executable


if __name__ == '__main__':
    DEFAULT_LOCATION = (Path.home() / '.python-venvs').expanduser()
    USAGE_STR = f"""
        The following syntax is valid when using this script/program:
            $ python(3.6[+]) {argv[0]} <pypi package to install globally>

        With an additional optional parameter at the end, for specifying
        where on the filesystem to put the virtualenv.
        (Defaults to '{DEFAULT_LOCATION}').
    """
    if len(argv) < 2:
        print(USAGE_STR, file=stderr)
        exit(2)
    if len(argv) >= 3:
        package, install_path = argv[1:3]
    else:
        package, install_path = argv[1], DEFAULT_LOCATION

    # Ensure existence of install path
    if '~' in str(install_path):
        install_path = install_path.expanduser()
    install_path = Path(install_path).resolve()
    if not install_path.is_dir():
        install_path.mkdir(parents=True)
        print(f"\tCreated missing install path: '{install_path}'.", file=stderr)
    install_path = install_path / package

    install_cmd = f"{executable} -m venv {install_path}"
    run(
        args=install_cmd.split(' '),
        stdout=PIPE, stderr=PIPE,
        universal_newlines=True,
    )
    print(
        f"\tCreated virtualenv for {package} at '{install_path}'.", file=stderr
    )

    # Remember to update PIP
    pip_binary = install_path / 'bin' / 'pip'
    update_pip = f"{pip_binary} install -U pip"
    run(
        args=update_pip.split(' '),
        stdout=PIPE, stderr=PIPE,
        universal_newlines=True,
    )
    print(f"\tUpdated pip in virtualenv '{install_path}'.", file=stderr)

    # Actual install:
    install_package = f"{pip_binary} install {package}"
    run(
        args=install_package.split(' '),
        stdout=PIPE, stderr=PIPE,
        universal_newlines=True,
    )
    print(
        f"\tInstalled package '{package}' in virtualenv at '{install_path}'.",
        file=stderr
    )

    with suppress(FileNotFoundError):
        package_bin = (pip_binary / '..' / package).resolve(strict=True)
        symlink = (Path.home() / 'bin').resolve(strict=True) / package
        if (
            symlink.exists() or
            not isinstance(package_bin, PosixPath)
        ):
            exit(0)
        answer = input(
            f"Do you want to create a symlink from "
            f"\n'{package_bin}' to \n'{symlink}'? [Y/n] "
        )
        if answer and not answer.lower().startswith('y'):
            exit(0)

        # Create symlink:
        symlink.symlink_to(package_bin)