Question

I have a script that needs to take in the name of a file and a set of key=value pairs. The set of key=value pairs is not defined. They are dependent on the file that was passed in.

eg:

Script.py file1 bob=1 sue=2 ben=3  # file 1 needs bob, sue, and ben

Script.py file2 mel=1 gorge=3 steve=3 # file 2 needs mel, gorge, and steve

Is this possible with argparse / optparse or do I have to build my own parser?

Answer 1

That should be fairly easy to parse yourself. Use of the helper libraries would be complicated by not knowing the keys in advance. The filename is in sys.argv[1]. You can build the dictionary with a list of strings split with the ‘=’ character as a delimiter.

import sys
filename = sys.argv[1]
args = dict([arg.split('=', maxsplit=1) for arg in sys.argv[2:]])
print filename
print args

Output:

$ Script.py file1 bob=1 sue=2 ben=3
file1
{'bob': '1', 'ben': '3', 'sue': '2'}

That’s the gist of it, but you may need more robust parsing of the key-value pairs than just splitting the string. Also, make sure you have at least two arguments in sys.argv before trying to extract the filename.