python using argparse.ArgumentParser method

Question

I've tried to learn how argparse.ArgumentParser works and I've write a couple lines for that :

global firstProduct
global secondProduct 
myparser=argparse.ArgumentParser(description='parser test')
myparser.add_argument("product1",help="enter product1",dest='product_1')
myparser.add_argument("product2",help="enter product2",dest='product_2')

args=myparser.parse_args()

firstProduct=args.product_1
secondProduct=args.product_2

I just want to that when User run this script with 2 parameters my code assign them to firstProduct and secondProduct respectively. However it doesn’t work. Is there anyone to tell me why? thanks in advance

Answer 1

In addition to unutbu's answer, you may also use the metavar attribute in order to make the destination variable and the variable name that appears in the help menus different, as shown in this link.

For example if you do:

myparser.add_argument("firstProduct", metavar="product_1", help="enter product1")

You will have the argument available for you in args.firstProduct but have it listed as product_1 in the help.

Answer 2

Omit the dest parameter when using a positional argument. The name supplied for the positional argument will be the name of the argument:

import argparse
myparser = argparse.ArgumentParser(description='parser test')
myparser.add_argument("product_1", help="enter product1")
myparser.add_argument("product_2", help="enter product2")

args = myparser.parse_args()
firstProduct = args.product_1
secondProduct = args.product_2
print(firstProduct, secondProduct)

Running % test.py foo bar prints

('foo', 'bar')