CODEWITHSUNDEEP
pythonpython-3.x
Nike
Nike

Reputation: 475

python argparse: default flag

My script needs to take exactly two arguments. The third one below is what I am struggling with.

python myscript -e arg1 arg2

python myscript -i arg1 arg2

python myscript arg1 arg2

I could easily get the first two to work using argparse but I couldn't figure out how to get the third one to work with argparse. Basically, when no flag is specified, I would like to do same processing as with -e flag specified. The script should error out if exactly 2 arguments haven't been specified.

I checked python documentation and saw that there is a way to specify a default value to a flag but I couldn't find a way to make the argument itself; a default one.

parser.add_argument('',nargs=2)

Although a newbie to python, I knew it was dumb to try the above thing, but somehow hoped that magically it would work. :)

Could someone help me find a way to get the no-argument case to work? Thanks

Upvotes: 4

Views: 1883

Answers (1)

alecxe
alecxe

Reputation: 473873

Just add arg1 and arg2 required positional arguments:

import argparse

parser = argparse.ArgumentParser()
parser.add_argument('-e', action='store_true')
parser.add_argument('-i', action='store_true')
parser.add_argument("arg1")
parser.add_argument("arg2")

args = parser.parse_args()
print(args)

Usage:

$ python test.py value1 value2 --help
usage: test.py [-h] [-e] [-i] arg1 arg2

positional arguments:
  arg1
  arg2

optional arguments:
  -h, --help  show this help message and exit
  -e
  -i

Upvotes: 3

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