Simple Virtual Environments Manager

myenv.py

#!/usr/bin/env python3
"""Virtual Environments Manager."""

import sys
import os
import subprocess
import shutil
import argparse

parser = argparse.ArgumentParser()

subparsers = parser.add_subparsers()
# ========================== 'new' subcommand ==========================
new_command = subparsers.add_parser("new",
                                    description="Create a new venv")
new_command.add_argument("name")
new_command.add_argument("-s", "--show-stdout", action="store_true")
new_command.add_argument("-p2", "--python2",
                         help="use python2 instead of python3",
                         action="store_true")
# ========================== 'list' subcommand ==========================
list_command = subparsers.add_parser("list")
# ========================= 'delete' subcommand =========================
delete_command = subparsers.add_parser("delete")
delete_command.add_argument("name")

commands = {}


COMMAND = "virtualenv {path} {options}"
app_dir = os.path.join(os.path.expanduser("~"), ".myenv")
env_dir = os.path.join(app_dir, "environments")
sym_dir = os.path.join(app_dir, "bins")


def cmd(name):
    """Command decorator."""
    def decorator(f):
        commands[name] = f
        return f
    return decorator


def main():
    """Run CLI."""
    paths = os.getenv("PATH").split(":")
    if sym_dir not in paths:
        print("warning: add '{}' to PATH".format(sym_dir))
    if not os.path.exists(env_dir):
        os.makedirs(env_dir)
    if not os.path.exists(sym_dir):
        os.makedirs(sym_dir)
    rest = sys.argv[1:]
    if len(rest) == 0:
        rest.append("--help")
    cmd = rest[0]
    args = parser.parse_args(rest)
    kwargs = dict(args._get_kwargs())
    commands[cmd](**kwargs)


def create_symlinks(name, path):
    """Create symlinks in bins directory."""
    os.system("ln {}/bin/activate {}/my_{}".format(path, sym_dir, name))


@cmd("list")
def _list():
    """List My Environments."""
    for env in os.listdir(env_dir):
        print("=> {}".format(env))


@cmd("new")
def new_environment(name, python2, show_stdout):
    """Create new virtualenv with python3."""
    path = os.path.join(env_dir, name)
    if os.path.exists(path):
        print("Err: environment with name '{}' already exists.".format(name))
        sys.exit(-1)
    opts = []
    if python2:
        opts.append("-p python2")
    else:
        opts.append("-p python3")
    option_str = " ".join(opts)
    cmd = COMMAND.format(path=path, options=option_str)
    if show_stdout:
        os.system(cmd)
    else:
        subprocess.check_output(cmd, shell=True)
        print("my_{}".format(name))
    create_symlinks(name, path)


@cmd("delete")
def delete_environment(name):
    """Delete an environment."""
    path = os.path.join(env_dir, name)
    sym_path = os.path.join(sym_dir, "my_{}".format(name))
    if os.path.exists(path):
        shutil.rmtree(path)
    if os.path.exists(sym_path):
        os.remove(sym_path)


if __name__ == '__main__':
    main()

1. mv myenv.py /usr/bin/myenv
2. chmod +x /usr/bin/myenv
3. Edit .bashrc and append ~/.myenv/bins/ to PATH
4. source $(myenv new hello)