mivade / arghelp

Python argparse helper

arghelp

Helpers for using argparse.

Introduction

Python's argparse module out of the box provides a rich set of tools for building command-line interfaces. While capable, more complex CLIs including subcommands require a great deal of verbosity; arghelp aims to simplify this.

Installation

Installing from source

arghelp uses flit. With recent versions of pip supprting pyproject.toml files simply run pip install .. Otherwise install flit first and use it to install:

pip install flit
flit install

Examples

Simple usage

from arghelp import Application, arg

app = Application([
    arg("-v", "--verbose", action="store_true"),
    arg("name")
])

args = app.parse_args()

greeting = "hello" if args.verbose else "hi"
print(f"{greeting}, {args.name}")

Example with output:

$ python demos/simple_demo.py -v Alex
hello, Alex
$ python demos/simple_demo.py Alexa
hi, Alexa

Defining a root command

from arghelp import Application, arg


app = Application([
    arg("-v", "--verbose", action="store_true"),
    arg("name")
])

@app.root_command()
def main(args):
    greeting = "hello" if args.verbose else "hi"
    print(f"{greeting}, {args.name}")


app.main()

Example with output:

$ python demos/simple_with_root.py -v Alexa
hello, Alexa
$ python demos/simple_with_root.py Alex
hi, Alex

Using subcommands

from arghelp import Application, arg


app = Application([
    arg("--verbose", "-v", action="store_true"),
])


@app.subcommand([arg("name")])
def hello(args):
    output = f"Hello, {args.name}!"

    if args.verbose:
        output += " How are you today?"

    print(output)


@app.subcommand([arg("name")])
def hi(args):
    output = f"Hi, {args.name}!"

    if args.verbose:
        output += " Hi hi hi!"

    print(output)


app.main()

Example with output:

$ python demos/subcmds.py -v hi Alex
Hi, Alex! Hi hi hi!
$ python demos/subcmds.py -v hello Alexa
Hello, Alexa! How are you today?

Subcommands and a root command

from arghelp import Application, arg

app = Application()


@app.root_command()
def main(_):
    print("Nothing to see here. Move along!")


@app.subcommand()
def droids(_):
    print("These aren't the droids you're looking for.")


@app.subcommand([arg("number", type=int)])
def square(args):
    print(args.number**2)


app.main()

Example with output:

$ python demos/subcmd_with_root.py
Nothing to see here. Move along!
$ python demos/subcmd_with_root.py droids
These aren't the droids you're looking for.
$ python demos/subcmd_with_root.py square 10
100

Mutually exclusive options

Mutually exclusive options are supported via the Group class:

from arghelp import Application, Group, arg

app = Application()


@app.subcommand(
    [
        arg("--verbose", "-v", action="store_true"),
        Group(
            [
                arg("-x", action="store_true", help="x mode"),
                arg("-y", action="store_true", help="y mode"),
            ],
            required=True,
        ),
    ]
)
def required(args):
    print(args)

For a complete example, see demos/groups.py.