docopt
Awhile back I came across a really cool Python library for command-line interfaces called docopt. I was exposed to it through this video.
The key idea is that you define the interface for your software and then docopt automatically generates a parser for you. I’ve included an example below, but the docopt website has very good documentation.
Example todo
Imagine you want two write a simple tool that takes an input file and writes and output file and has one option to provide an int.
tool input.txt output.txt -s 8
One way to write this would be to use argparse
import argparse
def parse_args():
parser = argparse.ArgumentParser()
parser.add_argument("input", help="The input text file", type=str)
parser.add_argument("output", help="The input text file", type=str)
parser.add_argument("-s", "--size", help="Integer window size", default=10, type=int)
args = parser.parse_args()
return args
def main():
args = parse_args()
# do stuff
if __name__ == '__main__':
main()
With docopt, you can do the following
"""Usage: use_docopt.py [-s=<win>] <input> <output>
Process input and write text file output. Uses window size provided, or default of 10.
Arguments:
input required input file
output required output file
Options:
-h --help. Show this screen.
-s=<win> --size Window size [default: 10].
"""
from docopt import docopt
def main():
arguments = docopt(__doc__)
# do stuff
if __name__ == '__main__':
main()
In this case it turns out that the docopt version is a little bit longer (one line), but it’s nice that you can customize the help message very easily.
Published on July 22, 2019