Reading named command arguments

Question

Can I use argparse to read named command line arguments that do not need to be in a specific order? I browsed through the documentation but most of it focused on displaying content based on the arguments provided (such as --h).

Right now, my script reads ordered, unnamed arguments:

myscript.py foo-val bar-val

using sys.argv:

foo = sys.argv[1] bar = sys.argv[2] 

But I would like to change the input so that it is order agnostic by naming arguments:

myscript.py --bar=bar-val --foo=foo-val

Answer 1

You can use the Optional Arguments like so:

import argparse, sys  parser=argparse.ArgumentParser()  parser.add_argument('--bar', help='Do the bar option') parser.add_argument('--foo', help='Foo the program')  args=parser.parse_args()  print args print sys 

Then if you call it with ./prog --bar=bar-val --foo foo-val it prints:

Namespace(bar='bar-val', foo='foo-val') ['Untitled 14.py', '--bar=bar-val', '--foo', 'foo-val'] 

Or, if the user wants help argparse builds that too:

 $ ./prog -h usage: Untitled 14.py [-h] [--bar BAR] [--foo FOO]  optional arguments:   -h, --help  show this help message and exit   --bar BAR   Do the bar option   --foo FOO   Foo the program 

Answer 2

The answer is yes. A quick look at the argparse documentation would have answered as well.

Here is a very simple example, argparse is able to handle far more specific needs.

import argparse  parser = argparse.ArgumentParser() parser.add_argument('--foo', '-f', help="a random options", type= str) parser.add_argument('--bar', '-b', help="a more random option", type= int, default= 0)  print(parser.format_help()) # usage: test_args_4.py [-h] [--foo FOO] [--bar BAR] #  # optional arguments: #   -h, --help         show this help message and exit #   --foo FOO, -f FOO  a random options #   --bar BAR, -b BAR  a more random option  args = parser.parse_args("--foo pouet".split()) print(args)  # Namespace(bar=0, foo='pouet') print(args.foo) # pouet print(args.bar) # 0 

Off course, in a real script, you won't hard-code the command-line options and will call parser.parse_args() (without argument) instead. It will make argparse take the sys.args list as command-line arguments.

You will be able to call this script this way:

test_args_4.py -h  # prints the help message test_args_4.py -f pouet  # foo="pouet", bar=0 (default value) test_args_4.py -b 42  # foo=None, bar=42 test_args_4.py -b 77 -f knock  # foo="knock", bar=77 

You will discover a lot of other features by reading the doc ;)