asyncclick 8.4.2.1

Composable command line interface toolkit, async fork

$ asyncclick_

Asyncclick is a fork of Click (described below) that works with trio or asyncio.

AsyncClick allows you to seamlessly use async command and subcommand handlers.

Click

Click is a Python package for creating beautiful command line interfaces in a composable way with as little code as necessary. It's the "Command Line Interface Creation Kit". It's highly configurable but comes with sensible defaults out of the box.

It aims to make the process of writing command line tools quick and fun while also preventing any frustration caused by the inability to implement an intended CLI API.

Click in three points:

• Arbitrary nesting of commands
• Automatic help page generation
• Supports lazy loading of subcommands at runtime

A Simple Example

import asyncclick as click
import anyio

@click.command()
@click.option("--count", default=1, help="Number of greetings.")
@click.option("--name", prompt="Your name", help="The person to greet.")
async def hello(count, name):
    """Simple program that greets NAME for a total of COUNT times."""
    for _ in range(count):
        click.echo(f"Hello, {name}!")
        await anyio.sleep(0.2)

if __name__ == '__main__':
    hello()
    # alternately: anyio.run(hello.main)

$ python hello.py --count=3
Your name: Click
Hello, Click!
Hello, Click!
Hello, Click!

Differences to Click

This async-ized version of Click is mostly backwards compatible for "normal" use: you can freely mix sync and async versions of your command handlers and callbacks.

Several advanced methods, most notably :meth:BaseCommand.main, and :meth:Context.invoke, are now asynchronous.

The :meth:BaseCommand.__call__ alias now invokes the main entry point via anyio.run. If you already have an async main program, simply use await cmd.main() instead of cmd().

:func:asyncclick.prompt is asynchronous and accepts a blocking parameter that switches between "doesn't affect your event loop but has unwanted effects when interrupted" (bugfix pending) and "pauses your event loop but is safe to interrupt" with Control-C". The latter is the default until we fix that bug.

You cannot use Click and AsyncClick in the same program. This is not a problem in practice, as replacing import click with import asyncclick as click, and from click import ... with from asyncclick import ..., should be all that's required.

Notable packages supporting asyncclick

• OpenTelemetry supports instrumenting asyncclick.

Donate

The Pallets organization develops and supports Click and other popular packages. In order to grow the community of contributors and users, and allow the maintainers to devote more time to the projects, please donate today.

The AsyncClick fork is maintained by Matthias Urlichs [e-mail].

Contributing

Click

See our detailed contributing documentation for many ways to contribute, including reporting issues, requesting features, asking or answering questions, and making PRs.

AsyncClick

You can file async-specific issues, ideally including a corresponding fix, to the MoaT/asyncclick repository on github.

Testing

If you find a bug, please add a testcase to prevent it from recurring.

In tests, you might wonder why runner.invoke is not called asynchronously. The reason is that there are far too many of these calls to modify them all. Thus tests/conftest.py contains a monkeypatch that turns this call into a thread that runs this call using anyio.run.