How to access a python argparse argument with a dot in the name

Question

Python's argparse lets me define argument names containing a dot in the name. But how can I access these ?

import argparse


parser = argparse.ArgumentParser()
parser.add_argument("inputfile.txt")
parser.add_argument("outputfile.txt")

args = parser.parse_args(['hello', 'world'])

# now args is:
# Namespace(inputfile.txt='hello', outputfile.txt='world')


# and this does not work
print(args.inputfile.txt)
>>> AttributeError: 'Namespace' object has no attribute 'inputfile'

Obviously attribute names can be created with a dot in their name but how can these be accessed ?

Edit: My goal was to let argparse display the inputfile.txt name (e.g. with --help) but call the attribute "inputfile".

After trying some of the suggestions the easiest way to accomplish this is using the metavar option:

parser.add_argument("inputfile", metavar="inputfile.txt")

Answer 1

Internally, argparse will add all attributes to the Namespace() instance with setattr. Accordingly, you can access the values with getattr:

getattr(args, 'inputfile.txt')

However, this is not as intuitive and in general attribute names with dots in them should be avoided. It is recommended to use the dest option of argparse.add_argument to define your own variable in which to store the value for that argument, as hd1 suggests in their answer.