Plain Python functions as CLI commands without boilerplate


Keywords
cli, command, line, argparse, optparse, argument, option
Licenses
LGPL-2.0/LGPL-3.0
Install
pip install argh==0.31.2

Documentation

Argh: The Effortless CLI

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The power of Argparse with plain Python functions!

Building a command-line interface? Found yourself uttering "argh!" while struggling with the API of argparse? Don't like the complexity but need the power?

Argh builds on the power of argparse (which comes with Python) and makes it really easy to use. It eliminates the complex API and lets you "dispatch" ordinary Python functions as CLI commands.

Installation

$ pip install argh

Example

import argh

def verify_paths(paths: list[str], *, verbose: bool = False):
    """
    Verify that all given paths exist.
    """
    for path in paths:
        if verbose:
            print(f"Checking {path}...")
        assert os.path.exists(path)

argh.dispatch_command(verify_paths)

Now you can run the script like this:

$ python app.py foo.txt bar/quux.txt

$ python app.py foo.txt bar/quux.txt --verbose
Checking foo.txt...
Checking bar/quux.txt...

$ python app.py -h
usage: app.py [-h] [-v] [paths ...]

Verify that all given paths exist.

positional arguments:
  paths          -

options:
  -h, --help     show this help message and exit
  -v, --verbose  False

Please check the documentation for examples of multiple commands, modularity, help generation, advanced type annotations inspection, decorators and more:

Why Argh?

Argh-powered applications are simple but flexible:

Pythonic, KISS

Commands are plain Python functions. Almost no CLI-specific API to learn.

Reusable

Endpoint functions can be used directly outside of CLI context.

Static typing friendly

100% of the code including endpoint functions can be type-checked. Argh is driven primarily by type annotations.

DRY

Don't Repeat Yourself. The amount of boilerplate code is minimal. Among other things, Argh will:

  • infer command name from function name;
  • infer arguments from function signature;
  • infer argument types, actions and much more from annotations.
Modular

Declaration of commands can be decoupled from assembling and dispatching.

Layered

The complexity of code raises with requirements.

Transparent

You can directly access argparse.ArgumentParser if needed.

Subcommands

Easily nested commands. Argh isolates the complexity of subparsers.

NIH free

Argh supports completion, progress bars and everything else by being friendly to excellent 3rd-party libraries. No need to reinvent the wheel.

Compact

No dependencies apart from Python's standard library.

See also the project page on GitHub, documentation and PyPI page.

Author

Developed by Andrey Mikhaylenko since 2010.

See contributors for a list of contributors to this library.

Contribute

The fastest way to improve this project is to submit tested and documented patches or detailed bug reports.

Donate

You can donate via Liberapay. This may speed up development or simply make the original author happy :)

Licensing

Argh is free software: you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.

Argh is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details.

You should have received a copy of the GNU Lesser General Public License along with Argh. If not, see <http://gnu.org/licenses/>.