how to use argparse in python 3 code example

Example 1: how to use argparse

import argparse

if __name__ == "__main__":
	#add a description
	parser = argparse.ArgumentParser(description="what the program does")

	#add the arguments
	parser.add_argument("arg1", help="advice on arg")
	parser.add_argument("arg2", help="advice on arg")
#						.
# 						.
#   					.
	parser.add_argument("argn", help="advice on arg")

	#this allows you to access the arguments via the object args
	args = parser.parse_args()

	#how to use the arguments
	args.arg1, args.arg2 ... args.argn

Example 2: python argparse file argument

import argparse

parser = argparse.ArgumentParser()
parser.add_argument('file', type=argparse.FileType('r'))
args = parser.parse_args()

print(args.file.readlines())

Example 3: argparse accept only few options

...
parser.add_argument('--val',
                    choices=['a', 'b', 'c'],
                    help='Special testing value')

args = parser.parse_args(sys.argv[1:])

Example 4: python argparser flags

parser.add_argument("-v", "--verbose", action="store_true",
                    help="verbose output")