Passing a List to Python From Command Line

Question

I would like to make my python script run from the command line when supplies with some arguments. However, one of the arguments should be a list of options specific to one

Answer 1

argparse is nice for this, it's in the standard library as of 2.7 and 3.2 but otherwise a pip install away.

Your main concern of specifying a variable-length list can be addressed by making the list interpreted as a single argument in the shell by using quotes (could depend on your shell I suppose):

% python prog.py 'name title address' spam

where prog.py contains

import sys
my_list = sys.argv[1].split() 
# my_list is ['name', 'title', 'address']
if 'name' in my_list:
   do_something()

or similar. Use an argument with split to delimit your list:

% python prog.py "you're a foo, lift the bar"

my_list = [x.strip() for x in  sys.argv[1].split(',')]
# my_list is ["you're a foo", "lift the bar"]

But please use argparse instead; especially if you want to use use -c style flags.

One way to interpret your question is:

"I'm already using argparse, since that's the sensible way to interpret command line arguments in Python. How do I specify that some options are within a specific category?"

In your question you've shown an example of something the shells I use of would choke on;

% python prog.py -v -details=['name', 'title', 'address'] --quickly -t 4

wouldn't make it to python to be parsed because they'd use spaces to separate arguments and might use [ and ] as shell syntax.

I suggest the following instead

% python prog.py -v --details name title address --quickly -t 4

where a prog.py file of

import argparse

parser = argparse.ArgumentParser() 
parser.add_argument('-v', action='store_true')
parser.add_argument('--details', nargs='*')
parser.add_argument('--quickly', action='store_true')
parser.add_argument('-t')

args = parser.parse_args()
#args is Namespace(details=['asdf', 'a', 'a'], quickly=False, t='4', v=True)
details = args.details
#details is ['asdf', 'a', 'a']

Now, as per your question, you didn't have to do the string parsing yourself.