twat 2.7.16

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twat

Twardoch's Workstation Automation Toolkit. A minimal plugin host for Python: install small, focused packages and access them all through one namespace and one CLI.

twat does nothing on its own. Install plugins, and they snap into place.

How it works

Python has a built-in mechanism for packages to register themselves with a group name — called entry points. twat uses this to build a dynamic namespace: when you access twat.fs, it looks up the twat.plugins entry point named fs, loads the module, and hands it back. No configuration files, no registration steps beyond a normal pip install.

import twat

# twat-fs registered itself as a "twat.plugins" entry point named "fs"
files = twat.fs.list_directory(".")

# twat-cache registered as "cache"
@twat.cache.memoize()
def expensive():
    ...

The CLI works the same way. twat fs list /tmp finds the fs plugin, rewrites sys.argv so the plugin thinks it was called directly, and calls twat_fs.main().

Install

pip install twat

twat is an empty host. Install plugins separately:

pip install twat-fs twat-cache twat-os

CLI

twat --help          # show host usage
twat --list          # list installed plugin entry point names
twat <plugin_name> [args...]

# Examples:
twat --list
twat fs list /tmp
twat cache clear

twat --list reads only plugin entry point metadata, so it does not import plugin modules just to show what is installed. Dispatch still works by loading the selected plugin, rewriting sys.argv so the plugin sees twat.<plugin> as its executable name, and calling the plugin module's callable main().

Writing a plugin

No SDK required. A plugin is a normal Python package that declares one entry point.

1. Package structure

twat-myplugin/
├── src/
│   └── twat_myplugin/
│       ├── __init__.py    # Public API — everything here becomes twat.myplugin.*
│       └── __main__.py    # CLI handler — must expose a main() function
├── pyproject.toml
└── README.md

2. Register the entry point (pyproject.toml)

[project.entry-points."twat.plugins"]
myplugin = "twat_myplugin"

This is the only twat-specific line in your entire package.

3. Expose your API (__init__.py)

from importlib import metadata

try:
    __version__ = metadata.version(__name__)
except metadata.PackageNotFoundError:
    __version__ = "0.0.0-dev"

def do_something():
    return "result"

# The CLI dispatcher calls plugin.main() — expose it here
try:
    from .__main__ import main
except ImportError:
    def main() -> None:
        pass

__all__ = ["do_something", "main", "__version__"]

4. Handle CLI calls (__main__.py)

import sys

def main() -> None:
    # sys.argv[0] is already "twat.myplugin" when called via `twat myplugin`
    print(f"Hello from myplugin! Args: {sys.argv[1:]}")
    sys.exit(0)

if __name__ == "__main__":
    main()

Naming conventions

Thing	Convention	Example
pip package	twat-<name> with hyphens	twat-myplugin
entry point name	lowercase, no prefix	myplugin
Python module	twat_<name> with underscores	twat_myplugin

The entry point name becomes the attribute on twat and the subcommand in the CLI.

How plugin loading works

twat.__getattr__ is called whenever you access an attribute that doesn't exist on the module. It scans the twat.plugins entry point group for a matching name, loads the module, registers it in sys.modules as twat.<name> (so subsequent accesses skip the lookup), and returns it.

If no plugin matches, a PluginError is raised with a clear message.

The CLI entry point (twat.main) intercepts sys.argv, pulls out the plugin name, rewrites sys.argv[0] to twat.<plugin> and sys.argv[1:] to the remaining arguments, then calls the plugin's main(). The plugin never knows it was dispatched through twat.

Development

git clone https://github.com/twardoch/twat
cd twat
uv venv && uv sync
pytest -xvs

License

MIT