python call function with arguments from dictionary

Question

I have a place in my script where I am asking user for some feedback (selecting the next stage in the script) and due to huge amount of items user is making decision from I wrapped my 'if-else' part into a dictionary. I am able to call any 'plain' function, but in a lot of cases I have to call the same function but with some arguments, but cannot figure out how to add these to the body of the script I already have. It looks like this (I will try to comment it so you see where I have a problem):

def runthis():

    # getting user input
    decide = input(str(
        'Select option 1'
        'Select option 2'
        'Select option 3'
        'Select option etc'
        'Select option n'))

    # each action listed here as a function without parentesis and arguments
    options = {
        '1': func1,
        '2': func2,
        '3': func3,
        'etc': funcetc,
        'n': funcn}

    # go through the list and look for key matching user decision
    # then run the value as a function - how to pass arguments when I need?
    if decide in options.keys():
        options[decide]()
    else:
        print('invalid entry')
        runthis()


runthis()

Thanks, any help much appreciated.

looks I found a solution finally: stackoverflow.com/questions/24580993/… — s3icc0
– s3icc0, Commented Apr 9, 2017 at 6:46

s3icc0 · Accepted Answer · 2017-04-09 06:59:25Z

1

Answer is simple - for the ones I need to add arguments I will just call the value as lambda ... like this:

# say func 2 holds 3 arguments
options = {
    '1': func1,
    '2': lambda: func2(arg1, arg2, arg3),
    '3': func3,
    'etc': funcetc,
    'n': funcn}

So easy solution and one does not see it

answered Apr 9, 2017 at 6:59

s3icc0

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Comments

AChampion · Accepted Answer · 2017-04-09 07:07:31Z

1

The functools module provides you means of manipulating functions including partial which allows you to partially pass in the arguments to a function, e.g.:

import functools
options = {
    ...
    '2': functools.partial(fn, arg1, arg2, arg3)
    ...
}

edited Apr 9, 2017 at 7:07

answered Apr 9, 2017 at 7:04

AChampion

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1 Comment

s3icc0 Over a year ago

didn't know that, thanks. I am still learning and functools is not even on my list 'need to know now' :-) actually isn't than the lambda solution better? (no import, easier syntax)

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