Calling functions with argparse

Question

I'm having issues calling functions from argpars. This is a simplified version of my script and this works, printing whatever value I give -s or -p

import argparse

def main():

    parser = argparse.ArgumentParser(description="Do you wish to scan for live hosts or conduct a port scan?")
    parser.add_argument("-s", dest='ip3octets', action='store', help='Enter the first three octets of the class C network to scan for live hosts')
    parser.add_argument("-p", dest='ip', action='store',help='conduct a portscan of specified host')

    args = parser.parse_args()

    print args.ip3octets
    print args.ip

This however, which to me is logically identical produces errors:

import argparse

def main():

    parser = argparse.ArgumentParser(description="Do you wish to scan for live hosts or conduct a port scan?")
    parser.add_argument("-s", dest='ip3octets', action='store', help='Enter the first three octets of the class C network to scan for live hosts')
    parser.add_argument("-p", dest='ip', action='store',help='conduct a portscan of specified host')

    args = parser.parse_args()

    printip3octets()
    printip()

def printip3octets():

    print args.ip3octets

def printip():

    print args.ip

if __name__ == "__main__":main()

Does anyone know where I am going wrong?

Answer 1

It is not identical, see this question for explanation why.

You have (at least) 2 options:

1. Pass the args as an argument to your function
2. Make args a global variable.

I'm not sure if others agree, but personally I would move all the parser functionality to be inside the if statement, i.e, the main would look like:

def main(args):
    printip3octets(args)
    printip(args)

Answer 2

args is a local variable in main() - you need to pass it as parameter to use it in other functions.

...
printip3octets(args)

def printip3octets(args):

    print args.ip3octets
...