The fastest, simplest way to create a CLI in Python

cli-buddy provides an ergonomic syntax for creating command-line interfaces in Python.

With cli-buddy, 👇 this code snippet is all it takes to build a CLI.

from cli_buddy import CLI

class MyCLI(CLI):
    arg: str

Under the hood, cli-buddy is a pydantic-flavored wrapper around the built-in argparse module.

Requirements

• Python 3.11+

Install

pip install cli-buddy

Usage

Use the CLI class to define your CLI's arguments and options.

This code snippet...

# main.py
from cli_buddy import CLI

class TerminalTimer(CLI):
    seconds: int
    # boolean fields are automatically converted to flags
    show_time: bool

... will produce the following CLI:

$ python main.py --help
usage: main.py [-h] seconds

positional arguments:
  seconds

options:
  -h, --help  show this help message and exit
  --show_time

A CLI class alone won't run anything, obviously. We need to define our behavior first.

Define your CLI's behavior

Either use your CLI instance however you like...

# main.py
...

cli = TerminalTimer()

for _ in range(cli.seconds):
    print(_)
    time.sleep(1)

... or just put your logic within the __call__() method of your CLI class...

class TerminalTimer(CLI):
    seconds: int
    show_time: bool

    def __call__(self):
        for _ in range(self.seconds):
            print(_)
            time.sleep(1)

TerminalTimer()  # That's it!

Give your arguments default values to convert arguments to flags.

The CLI class will automatically convert arguments to flags if:

• they are assigned a default value,
• or if the field is a boolean.

For example, this...

class TerminalTimer(CLI):
    seconds: int = 1
    show_time: bool

... will produce the following CLI:

$ python main.py --help
usage: main.py [-h] [--seconds SECONDS] [--show_time]

options:
  -h, --help         show this help message and exit
  --seconds SECONDS  (default: 1)
  --show_time

Use the Argument class to further configure your CLI's arguments.

The Argument function takes the same arguments as the built-in argparse.ArgumentParser.add_argument function.

For example, this...

from cli_buddy import CLI, Argument


class TerminalTimer(CLI):
    seconds: int = Argument(help="Number of seconds to wait")
    show_time: bool = Argument("-t", help="Show seconds in terminal", action="store_true")

... will produce the following CLI:

$ python main.py --help
usage: main.py [-h] -t seconds

positional arguments:
  seconds          Number of seconds to wait

options:
  -h, --help       show this help message and exit
  -t, --show_time  Show seconds in terminal