dataparsers 0.1.0

A wrapper around argparse to get command line argument parsers from dataclasses

dataparsers

A wrapper around argparse to get command line argument parsers from dataclasses.

Installation

   pip install dataparsers

Basic usage

Create a dataclass describing your command line interface, and call parse() with the class:

# prog.py
from dataclasses import dataclass
from dataparsers import parse

@dataclass
class Args:
    foo: str
    bar: int = 42

args = parse(Args)
print("Printing `args`:")
print(args)

The dataclass fields that have a "default" value are turned into optional arguments, while the non default fields will be positional arguments.

The script can then be used in the same way as used with argparse:

$ python prog.py -h
usage: prog.py [-h] [--bar BAR] foo

positional arguments:
  foo

options:
  -h, --help  show this help message and exit
  --bar BAR

And the resulting type of args is Args (recognized by type checkers and autocompletes):

$ python prog.py test --bar 12
Printing `args`:
Args(foo='test', bar=12)

Argument specification

To specify detailed information about each argument, call the arg() function on the dataclass fields:

# prog.py
from dataclasses import dataclass
from dataparsers import parse, arg

@dataclass
class Args:
    foo: str = arg(help="foo help")
    bar: int = arg(default=42, help="bar help")

args = parse(Args)

It allows to customize the interface:

$ python prog.py -h
usage: prog.py [-h] [--bar BAR] foo

positional arguments:
  foo         foo help

options:
  -h, --help  show this help message and exit
  --bar BAR   bar help

In general, the arg() function accepts all parameters that are used in the original add_argument() method (with few exceptions) and some additional parameters. The default keyword argument used above makes the argument optional (i.e., passed with flags like --bar) except in some specific situations.

One parameter of add_argument() that are not possible to pass to arg() is the dest keyword argument. That's because the name of the class attribute is determined by the dataclass field name. So, it is unnecessary to pass the dest parameter, since it doesn't makes sense in this situation.

Documentation

For more information, see the documentation.