config-argument-parser

A package to help automatically create command-line interface from configuration or code.

It contains two modules CAP🧢(ConfigArgumentParser) and TAP🚰(TypeArgumentParser).

Read the documentation here.

Motivation

Configuration files are highly readable and useful for specifying options, but sometimes they are not convenient as command-line interface. However, it requires writing a lot of code to produce a CLI. This package automates the building process, by utilizing the Python standard libraries configparser and argparse.

The design is to minimize the changes to your original scripts, so as to facilitate maintenance.

Features

• Only a few extra lines are needed to build a CLI from an existing script.
• The comments are parsed as help messages. (Most libraries do not preserve the comments.)
• Consistent format between configuration and script provides ease of use.

Usage

Case 1: create CLI from an object

If you used class to store arguments, create a script example.py as below. Default arguments are defined as class attributes, and parsed arguments are stored as instance attributes. The good is that auto-completion can be triggered in editors.

For the best practice, see Case 4.

import configargparser

class Args:
    # Help message of the first argument. Help is optional.
    a_string = "abc"
    a_float = 1.23  # inline comments are omitted
    # Help can span multiple lines.
    # This is another line.
    a_boolean = False
    an_integer = 0

args = Args()

parser = configargparser.ConfigArgumentParser()
# if `shorts` is provided, add short options for the first few arguments in order
parser.parse_obj(args, shorts="sfb")

print(args.a_string)
print(args.a_float)
print(args.a_boolean)
print(args.an_integer)

In fact, only the snippet below is added to the original script. Moreover, removing this minimal modification does not affect the original script.

import configargparser
parser = configargparser.ConfigArgumentParser()
parser.parse_obj(args)

Show help, python example.py -h:

$ python example.py -h
usage: example.py [-h] [-s A_STRING] [-f A_FLOAT] [-b] [--an-integer AN_INTEGER]

optional arguments:
  -h, --help            show this help message and exit
  -s A_STRING, --a-string A_STRING
                        Help message of the first argument. Help is optional. (default: abc)
  -f A_FLOAT, --a-float A_FLOAT
                        (default: 1.23)
  -b, --a-boolean       Help can span multiple lines. This is another line. (default: False)
  --an-integer AN_INTEGER
                        (default: 0)

Run with options, for example, python example.py -b -f 1:

$ python example.py -b -f 1
abc
1.0
True
0

Note that the values are changed.

Case 2: create CLI from configuration

If you used configuration file, create an example script example.py:

import configargparser

parser = configargparser.ConfigArgumentParser()
parser.read("config.ini")
parser.parse_args(shorts="sfb")

print("Configs:", parser.defaults)
print("Args:   ", parser.args)

Create a configuration file config.ini in the same directory:

[DEFAULT]
# Help message of the first argument. Help is optional.
a_string = 'abc'
a_float = 1.23  # inline comments are omitted
# Help can span multiple lines.
# This is another line.
a_boolean = False
an_integer = 0

Regular run, python example.py:

$ python example.py
Configs: {'a_string': 'abc', 'a_float': 1.23, 'a_boolean': False, 'an_integer': 0}
Args:    {'a_string': 'abc', 'a_float': 1.23, 'a_boolean': False, 'an_integer': 0}

Run with options, such as python example.py -b -f 1:

$ python example.py -b -f 1
Configs: {'a_string': 'abc', 'a_float': 1.23, 'a_boolean': False, 'an_integer': 0}
Args:    {'a_string': 'abc', 'a_float': 1.0, 'a_boolean': True, 'an_integer': 0}

Case 3: create CLI from script itself

If you used global variables, create a script example.py, with the variables defined at top of file as below:

# [DEFAULT]
# Help message of the first argument. Help is optional.
a_string = "abc"
a_float = 1.23  # inline comments are omitted
# Help can span multiple lines.
# This is another line.
a_boolean = False
an_integer = 0
# [END]

import configargparser

parser = configargparser.ConfigArgumentParser()
parser.read_py("example.py")
parser.parse_args(shorts="sfb")

# update global variables
globals().update(parser.args)
print(a_string)
print(a_float)
print(a_boolean)
print(an_integer)

Use it as in case 1. For example, python example.py -b -f 1:

$ python example.py -b -f 1
abc
1.0
True
0

Case 4: create CLI from a dataclass object (preferred)

Suppose you have a script example.py below, which uses a dataclass object to store arguments:

from dataclasses import dataclass

@dataclass
class Args:
    # Help message of the first argument. Help is optional.
    a_string: str = "abc"
    a_float: float = 1.23  # inline comments are omitted
    # Help can span multiple lines.
    # This is another line.
    a_boolean: bool = False
    an_integer: int = 0

args = Args()

print(args.__dict__)

Add these lines to the script to create CLI:

import configargparser
parser = configargparser.TypeArgumentParser()
parser.parse_obj(args, shorts="sfb")

print(args.__dict__)

Use it as in case 1. For example, python example.py -b -f 1 to change the values:

$ python example.py -b -f 1
{'a_string': 'abc', 'a_float': 1.0, 'a_boolean': True, 'an_integer': 0}

Installation

Install from PyPI:

python -m pip install --upgrade pip
pip install config-argument-parser

Alternatively, install from source:

git clone https://github.com/yuanx749/config-argument-parser.git
cd config-argument-parser

then install in development mode:

git checkout main
python -m pip install --upgrade pip
pip install -e .

or:

git checkout dev
python -m pip install --upgrade pip
pip install -e .[dev]
pre-commit install

Uninstall:

pip uninstall config-argument-parser

Notes

This package uses Semantic Versioning.