ignore a def if not in use?

Question

I have the following script -

import os, errno
import argparse

def removecompressed(filename):
    try:
        os.remove(filename)
        print('Removing {}'.format(args.compressedfile))
    except OSError as e: # this would be "except OSError, e:" before Python 2.6
        print ('File {} does not exist in location {}!'.format(args.compressedfile, args.localpath))
        if e.errno != errno.ENOENT: # errno.ENOENT = no such file or directory
            raise # re-raise exception if a different error occured

def removeencrypted(filename):
    try:
        os.remove(filename)
        print('Removing {}'.format(args.encryptedfile))
    except OSError as e: # this would be "except OSError, e:" before Python 2.6
        print ('File {} does not exist in location {}!'.format(args.encryptedfile, args.localpath))
        if e.errno != errno.ENOENT: # errno.ENOENT = no such file or directory
            raise # re-raise exception if a different error occured

parser = argparse.ArgumentParser()
parser.add_argument('-p', '--localpath', type=str, default='', help="the path containing the files")
parser.add_argument('-c', '--compressedfile', type=str, default='', help="the compressed file to be deleted")
parser.add_argument('-e', '--encryptedfile', type=str, default='', help="the encrypted file to be deleted")
args = parser.parse_args()

removecompressed(args.localpath + args.compressedfile)
removeencrypted(args.localpath + args.encryptedfile)

But I want the -e and -c arguments to be optional. How would I go about doing this?

I understand this reply: Argparse optional positional arguments?

but the problem is that the def is parsing 2 strings together first to make the filename. If I remove one of the arguments it complains about adding a string and a none value.

edit - if I use all 3 arguments there's no problem. If I remove the -e or -c for example here I've removed the -e I get the following exception -

Traceback (most recent call last):
  File "cleanup.py", line 35, in <module>
    removeencrypted(args.localpath + args.encryptedfile)
TypeError: Can't convert 'NoneType' object to str implicitly

I've updated my arguments to include default=''

Use an `if` statement to test whether your argument if `None`? — , May 12 '14 at 15:03

score 2 · Answer 1 · answered May 12 '14 at 15:06

It's unclear from your question what should happen if one of those arguments isn't provided, but in principle, you probably want to provide a default value:

parser.add_argument('-c', '--compressedfile', type=str, default='', help="the compressed file to be deleted")

This is the value which will be used if the particular command flag isn't provided on the command line.

^{Note that you're not using optional positional arguments, you're using optional regular arguments (which is the default behavior).}

I've updated to include the error I get when removing one of the arguments (-e). I also included the default='' value. — whoisearth, May 12 '14 at 16:53

ignore a def if not in use?

1 Answers1