Python: Choose function in command line argument

Question

In a Python program (with more than one user defined functions), I want to specify which function to use through command line arguments. For e.g., I have the following functions, func1(), func2(), func3() in my Python program, and I am using the following technique presently:

python prog.py -func func2"

My program is something like this:

from __future__ import division
import numpy as np
import argparse

parser = argparse.ArgumentParser(description='')
parser.add_argument('-func', help='')
args = parser.parse_args()
func_type = globals()[args.func]()

def func1(): 
    print "something1"
def func2(): 
    print "something2"
def func3(): 
    print "something3"

func_type()

I get the following error:

KeyError: 'func2'

I will really appreciate if someone can tell me how I can implement the desired functionality.

m0dem · Accepted Answer · 2017-04-23 23:49:11Z

2

Two simple mistakes related to func_type = globals()[args.func]()

The functions you are looking for have not been defined yet. Move the function definitions above this line.
You are calling the function instead of saving a reference to it in variable func_type.

edited Apr 23, 2017 at 23:49

answered Apr 23, 2017 at 23:41

m0dem

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2 Comments

Galen Long Over a year ago

And also, like you said in an earlier edit, the functions need to be defined before they're looked up in globals. So in addition to removing the parentheses, @SiddTheKid should move all three function declarations above the argument parsing block.

m0dem Over a year ago

Adding that back. :) Thanks @galenlong.

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