dcflags 0.2.1

Dataclass fields as cmd args and env vars

dcflags

Python package for initializing a dataclass with arguments from the command line or values from environmental variables. Meant to work as an entrypoint for applications, nothing else.

Install

dcflags is available through pip

pip install dcflags

Usage

# main.py

import dataclasses
import dcflags


@dataclasses.dataclass
class Config:
    output: str
    workers: int = 1
    verbose: bool = False


if __name__ == "__main__":
    cfg = dcflags.parse(Config)
    print(cfg)

# help message
$ python main.py --help
usage: main.py [-h] [--output OUTPUT] [--workers WORKERS] [--verbose [VERBOSE]]

options:
  -h, --help           show this help message and exit
  --output OUTPUT      type: str, env: $OUTPUT
  --workers WORKERS    type: int, env: $WORKERS, default: 1
  --verbose [VERBOSE]  type: bool, env: $VERBOSE, default: False

# missing required argument
$ python main.py
usage: main.py [-h] [--output OUTPUT] [--workers WORKERS] [--verbose [VERBOSE]]
main.py: error: the following arguments are required: --output/$OUTPUT

# command line arguments
$ python main.py --output=file.txt
Config(output='file.txt', workers=1, verbose=False)

# env vars
$ OUTPUT=test.txt python main.py
Config(output='test.txt', workers=1, verbose=False)

# a bit of everything
$ OUTPUT=new.txt python main.py --verbose --workers=3
Config(output='new.txt', workers=3, verbose=True)