Passing Python variables via command line?

I'm new to Python (as in, yesterday), so bear with me if I don't know 'the obvious' yet.

There are two ways I could go about this, and either would work fine for me, and I'm not sure if getopt or optparse contains what I want/need (from what I'm reading)? I would like to do something similar to the following:

getopt

optparse

python this.py --variable VariableName="Value" -v VariableName2="Value2"


OR

python this.py --VariableName "Value"


The main issue I'm facing is that I may need to optionally pass any of the variables in, but not necessarily all and in any particular order (ergo, a raw sys.argv won't work in my case). For some of these variables, I may be passing strings, numbers and/or arrays.

sys.argv

Once the variables are passed in the script, one way or another I'll need to check if they are set / not null and assign default values as necessary.

Thanks!

3 Answers
3

You definitely want a commandline argument parser. Python ships with a few. Python2.7 has argparse which can be back-ported to earlier versions as necessary and is what I would recommend. There's also optparse. It's not quite as nice as argparse, but it can still do a good bit and is available with older python versions as well as newer ones.

argparse

optparse

argparse

There's also getopt, but that one is hardly worth mentioning in comparison to the others.

getopt

I'm going to do a first and answer my own question.

As much as I like the answer @mgilson gave, I found an 'easier' way. I'm very comfortable with regular expressions, and figuring out an associative array (i.e., Dictionary) isn't too difficult.

import re

args =
args['pythonFile'] = sys.argv[0]

for arg in sys.argv[1:]:
variable = re.search('--(.*)=',arg)
variable = variable.group(1)
value = re.search('=(.*)',arg)
value = value.group(1)
args[variable] = value

print args


Here's the proof:

$ /opt/python27/bin/python2.7 Test.py --var1=1 --var2="Testing This"
'var1': '1', 'pythonFile': 'Test.py', 'var2': 'Testing This'


Woot!

I refactored the above code a little to be more flexible and modular (great solution by the way). You can now add something like --dev instead of --dev=true. Or you can do both. It also wont crash the app if you don't add any args.

--dev

--dev=true

def get_cli_args():
"""
Returns a dictionary of arguments passed to through the CLI.
"""

import re
import sys

args =

for arg in sys.argv[1:]:
var = re.search('--([A-Za-z]*)', arg) # optional value assignment
var = var.group(1)
value = re.search('=(.*)', arg)
value = value.group(1) if value else None
args[var] = value

return args


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