Passing no arguments while calling function through dict

Question

I have made a Python script which calls functions based on user's input. Until now I was calling argument-less functions simply through a dict

options = { 0 : func0,
            1 : func1,
            2 : func2,
           }
options[choice]()

Now I am in a situation where I need to call a few functions with arguments. I am new to Python and I tried something like this

options = { 0 : (func0,None),
            1 : (func1,None),
            2 : (func2,foo1),
            3 : (func3,foo2),
          }
options[choice][0](options[choice][1])

I am aware why None doesn't work here, and have written it just to symbolize that the function doesn't take any arguments. What changes should I make in the code so that it works for all kinds of functions?

I tried unpacking empty dict but it doesn't work either.

Answer 1

None is still a value, and passing it to a function that is not expecting arguments will not work. Instead consider using partial here

from functools import partial

options = { 0: func0,
            1: func1,
            2: partial(func2, foo1),
            3: partial(func3, foo2),
          }

options[choice]()

Answer 2

Use a lists of arguments:

options = { 0 : (func0, []),
            1 : (func1, []),
            2 : (func2, [foo1]),
            3 : (func3, [foo2]),
          }
options[choice][0](*options[choice][1])
# or
func, args = options[choice]
func(*args)

If you want to be able to specify named arguments as well, you can extend it like this:

options = { 0 : (func0, [], {}),
            1 : (func1, [], {param_name: value}),
            2 : (print_name, [], {name: "nims"}),
            3 : (func3, [foo2], {}),
          }
func, args, kwargs = options[choice]
func(*args, **kwargs)

Answer 3

You could use lambda expressions for the functions with arguments (and leave the ones without as you have them now):

options = { 0 : func0,
            1 : func1,
            2 : lambda: func2(foo1),
            3 : lambda: func3(foo2),
          }

Answer 4

try something like this :

use * in function header, it'll collect all the arguments in a tuple.

def func0(*a):
    print list(a)
def func1(*a):
    print list(a)
def func2(*a):
    print list(a)
def func3(*a):
    print list(a)
foo1=1
foo2=2
options = { 0 : (func0,None),
            1 : (func1,None),
            2 : (func2,foo1),
            3 : (func3,foo2),
          }
choice=2
options[choice][0](options[choice][1:])  #prints [(1,)]

choice=1
options[choice][0](options[choice][1:])  #prints [(None,)]