python multiple output variables as input

Question

def function_1(a,b,c,d):
    print('{}{}{}{}'.format(a,b,c,d))
    return

def function_2():
   t=y=u=i= 5
   return t,y,u,i

function_1(function_2())

I expect that python would execute function 2 first, and return each t, y, u and i as inputs to function1, but instead I get:

TypeError: function_1() missing 3 required positional arguments: 'b', 'c', and 'd'

I understand that either the output of function2 is in a single object, or it is treating function2 as an input function, instead of executing.

how do I change my code to execute as expected? (each of the output variables from function2 treated as input variables to function1)

Also THANK YOU for producing a minimal complete verifiable example. That's a huge thing that adds to ease of answering. — Adam Smith
– Adam Smith, Commented Nov 12, 2018 at 1:06

Adam Smith · Accepted Answer · 2018-11-12 01:18:25Z

4

You need a splat operator.

function_1(*function_2())

function_2() returns a tuple (5, 5, 5, 5). To pass that as a set of four parameters (rather than one four-element tuple as one parameter), you use the splat operator *

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edited Nov 12, 2018 at 1:18

answered Nov 12, 2018 at 1:04

Adam Smith

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Comments

LeKhan9 · Accepted Answer · 2018-11-12 01:45:49Z

0

This might be a slightly awkward way of doing it, but you can actually pss the function as a parameter itself, and then decompose it!

def function_1(func):
    print('{}{}{}{}'.format(*func))
    return

def function_2():
   t=y=u=i= 5
   return t,y,u,i

function_1(function_2())

output:

answered Nov 12, 2018 at 1:45

LeKhan9

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