Python: Misunderstanding of pickle & getOpt

Question

I'm testing out pickling & getOpts, have been successful with each individually, but now that I'm trying to combine the two I'm having trouble. Below is a snippet of what I'm doing,

#! /usr/bin/env python

from itertools import groupby, chain
import pickle
import getopt
import sys

def main():

    # default values
    var1 = 6
    var2 = 7
    var3 = 4

    try:
        opts, args = getopt.getopt(sys.argv[1:], 'l:z', ['load=', 'help'])
    except getopt.GetoptError:
        usage()
        sys.exit(2)

    for opt, arg in opts:
        if opt in ('-z', '--help'):
            usage()
            sys.exit(2)
        elif opt in ('-l', '--load'):
            pkl_file = open('data.pkl', 'rb')
            settings = pickle.load(pkl_file)
            var1 = settings[0]
            var2 = settings[1]
            var3 = settings[2]
            pkl_file.close()
        else:
            usage()
            sys.exit(2)

    print ("\nthe values are as follows")
    print ("cvar1: " + str(var1))
    print ("var2: " + str(var2))
    print ("var3: " + str(var3))

if __name__ == "__main__":
    main()

and when pickling the data I use the following code

#! /usr/bin/env python

import pickle

settings =  [3, 15, 4]

output = open('data.pkl', 'wb')

# Pickle dictionary using protocol 0.
pickle.dump(settings, output)

output.close()

However, when I try to run with the '-l' flag, I get the following error

NameError: global name 'usage' is not defined

Any idea why this is happening? Thanks in advance!

Answer 1

You are calling a function you haven't defined (usage()). You need to implement this function, or else your code wont' run.