refract-venv 0.1.0

Lightweight Virtual Environment Manager for Python

Refract centralizes your Python virtual environments in a single location, providing simple commands to create, manage, and switch between project contexts—without the complexity of traditional virtual environment tools.

Demo

Features

• Centralized Management: All environments stored in ~/.refract/envs/
• Simple Commands: Intuitive syntax that's easy to remember
• Global Access: Use refract from anywhere in your system
• Zero Dependencies: Only requires Python standard library
• Seamless Switching: Instant environment activation with new shell sessions
• Colored Prompts: Clear visual indication of active environment in shell prompt
• Clean Organization: Automatic directory structure management

Table of Contents

• Demo
• Installation
• Quick Start
• Commands Reference
• Usage Examples
• Troubleshooting
• Contributing

Installation

Refract itself depends only on Python's standard library. The refract command and refract install (shell integration) are separate steps.

macOS and Linux only. Windows is not supported.

Prerequisites

• Python 3.10 or higher
• bash or zsh

pip is optional. pipx is optional.

From source (Python 3 only)

Best for minimal servers that may not have pip:

git clone git@github.com:YakShavingCatHerder/refract.git
cd refract
./install.sh
source ~/.zshrc    # bash: source ~/.bashrc

This copies refract.py to ~/.local/bin/refract, then runs refract install.

From source with pip

git clone git@github.com:YakShavingCatHerder/refract.git
cd refract
./install.sh --pip
source ~/.zshrc    # bash: source ~/.bashrc

From source with pipx (optional)

./install.sh --pipx
source ~/.zshrc    # bash: source ~/.bashrc

From PyPI

The distribution name is refract-venv. The command is refract.

pip install refract-venv
refract install
source ~/.zshrc    # bash: source ~/.bashrc

If you already use pipx for CLI tools:

pipx install refract-venv
refract install
source ~/.zshrc    # bash: source ~/.bashrc

What refract install does

• Creates ~/.refract/ and refract.json (default colorway: green/black)
• Installs prompt integration in ~/.zshrc and ~/.bashrc
• Installs the shell wrapper in both files (reloads after refract colorway)
• Tells you to restart or source your shell

It does not install the refract executable. Re-running it is idempotent: existing snippets are updated, not duplicated.

Uninstall

From a source checkout:

./uninstall.sh

If you installed the package:

pip uninstall refract-venv
# or: pipx uninstall refract-venv

Virtual environments in ~/.refract/envs/ are left in place. Remove them with rm -rf ~/.refract.

Quick Start

After installation, you can immediately start using refract:

# Create your first environment
refract init myproject

# List all environments
refract list

# Activate an environment
refract use myproject

# Remove an environment when done
refract rm myproject

Commands Reference

refract init <name>

Creates a new virtual environment with the specified name.

Parameters:

• environment_name: Must be a valid Python identifier (letters, numbers, underscores only)

Example:

$ refract init django_project
Created new virtualenv at /path/to/.refract/envs/django_project

What happens:

• Creates a new virtual environment in ~/.refract/envs/<name>/
• Uses Python's built-in venv module
• Validates the environment name format
• Prevents duplicate environment creation

refract list

Displays all available virtual environments.

Example Output:

$ refract list
Available virtualenvs:
  * django_project
  * flask_api
  * data_analysis
  * machine_learning

What happens:

• Scans ~/.refract/envs/ directory
• Lists all subdirectories as available environments
• Shows helpful message if no environments exist

refract use <name>

Activates the specified virtual environment by opening a new shell session.

Example:

$ refract use django_project
[refract] Switching to environment 'django_project'...

What happens:

1. Validates the environment exists
2. Creates a temporary activation script that:

• Sources your shell profile files (.bash_profile, .zshrc, etc.)
• Activates the virtual environment
• Opens a new shell session with the environment active
• Sets up colored prompt showing the active refract environment with [refract:name] prefix

3. Runs the script in a new shell process
4. Removes the temporary script as a cleanup process

After activation, you'll see:

[refract:django_project] user@machine ~ %

refract rm <name>

Removes the specified virtual environment.

Example:

$ refract rm old_project
Removed environment 'old_project'

What happens:

• Validates the environment exists
• Completely removes the environment directory
• Provides confirmation message

refract current

Shows the currently active refract environment.

Example:

$ refract current
Currently in refract environment: django_project

What happens:

• Checks for the REFRACT_ENV environment variable
• Displays the active environment name in light gray if one is active
• Shows "No refract environment currently active" if none is active

refract install

Initializes Refract config and shell integration. The executable must already be on your PATH (via ./install.sh, pip, or pipx).

What happens:

• Creates ~/.refract/ and refract.json if needed
• Writes prompt hooks and the shell wrapper into ~/.zshrc and ~/.bashrc
• Does not create a symlink or install the refract command

Usage Examples

Example 1: Web Development Workflow

# Create environments for different projects
$ refract init frontend
Created new virtualenv at /Users/path/.refract/envs/frontend

$ refract init backend
Created new virtualenv at /Users/path/.refract/envs/backend

# List all environments
$ refract list
Available virtualenvs:
  * frontend
  * backend

# Switch to frontend work
$ refract use frontend
[refract] Switching to environment 'frontend'...

# In the new shell session:
[refract:frontend] $ npm install
[refract:frontend] $ npm start

# Switch to backend work (in another terminal)
$ refract use backend
[refract] Switching to environment 'backend'...

# In the new shell session:
[refract:backend] $ pip install django
[refract:backend] $ python manage.py runserver

Example 2: Data Science Workflow

# Create specialized environments
$ refract init data_analysis
$ refract init ml_experiment
$ refract init visualization

# Switch between different analysis contexts
$ refract use data_analysis
[refract:data_analysis] $ pip install pandas numpy matplotlib

$ refract use ml_experiment
[refract:ml_experiment] $ pip install scikit-learn tensorflow

$ refract use visualization
[refract:visualization] $ pip install plotly seaborn bokeh

Example 3: Project Cleanup

# List all environments
$ refract list
Available virtualenvs:
  * old_project
  * experiment_1
  * experiment_2
  * current_project

# Remove completed experiments
$ refract rm experiment_1
Removed environment 'experiment_1'

$ refract rm experiment_2
Removed environment 'experiment_2'

# Verify cleanup
$ refract list
Available virtualenvs:
  * old_project
  * current_project

Directory Structure

Refract creates and manages the following structure:

~/.refract/
├── envs/                    # All virtual environments
│   ├── project_a/
│   │   ├── bin/
│   │   ├── lib/
│   │   └── ...
│   ├── project_b/
│   │   ├── bin/
│   │   ├── lib/
│   │   └── ...
│   └── ...
└── refract.json            # Configuration file

Colored Prompts Feature

Refract automatically modifies your shell prompt to show the active environment:

• Format: [refract:environment_name] appears at the beginning of your prompt
• Color: Green background with black text by default to make current venv easily visible
• Shell Support: Works with both bash and zsh
• Environment Variable: Sets REFRACT_ENV for programmatic access

Troubleshooting

Common Issues

"command not found: refract"

Problem: The refract command isn't available globally.

Solution:

# From a source checkout, install the command then shell integration
./install.sh

# If the command exists but shell hooks do not
refract install

# Make sure ~/.local/bin is on PATH
echo 'export PATH="$HOME/.local/bin:$PATH"' >> ~/.zshrc
source ~/.zshrc

Refract environment is active, but prompt prefix is missing

Problem: refract use <name> activates the environment, but [refract:<name>] is not shown in your prompt.

Why this happens: Some shell themes/frameworks rebuild the prompt and can override custom prompt text.

How to verify activation:

echo $REFRACT_ENV
which python

If active, REFRACT_ENV should contain your environment name and which python should point to ~/.refract/envs/<name>/bin/python.

"Permission denied: refract"

Problem: The installed script does not have execute permissions.

Solution:

chmod +x ~/.local/bin/refract

"Environment 'name' does not exist"

Problem: Trying to use an environment that hasn't been created.

Solution:

# Check available environments
refract list

# Create the environment first
refract init name

"Environment name must be a valid identifier"

Problem: Using invalid characters in environment names.

Solution: Use only letters, numbers, and underscores:

#  Valid names
refract init my_project
refract init project123
refract init _private

#  Invalid names
refract init my-project    # hyphens not allowed
refract init "my project"  # spaces not allowed
refract init my.project    # dots not allowed

Debug Mode

Enable debug output to troubleshoot issues:

refract --debug list

This will show additional information about paths and configuration.

Manual Environment Management

If you need to manually manage environments:

# List all environments
ls ~/.refract/envs/

# Remove an environment manually
rm -rf ~/.refract/envs/environment_name

# Check refract configuration
cat ~/.refract/refract.json

Contributing

Development Setup

1. Clone the repository
2. Install from source:

   ./install.sh --pip
   

Testing

CLI tests use a temporary HOME and require refract on PATH (install the wheel or run ./install.sh --pip first):

python -m unittest discover -s tests -v -p 'test_cli.py'

./install.sh methods are tested in CI with REFRACT_TEST_INSTALL_SH=1.

Regenerate the README GIF with VHS:

./demo/record.sh

Code Style

• Follow PEP 8 guidelines
• Use descriptive variable names
• Add docstrings to functions
• Include error handling

License

This project is licensed under the MIT License - see the LICENSE file for details.

Acknowledgments

• Built with 1 dependency: Python's standard library
• Inspired by the need for simpler, cli-native management of virtual environments; perfect for deploying to lightweight servers when needed
• Thanks to the Python community for the excellent venv module; this isn't a diss, just a specific use-case ;)

**Happy coding with refract! **