How to call a function with return value inside an if statement in python

Question

I have two functions with one containing a return statement. My agenda is when the first function executes in the if condition, compiler is throwing a syntax error.

Here's my script.

def hi():
  return 10,20

def hello(a):
  if a:
    print "asd"

if a,b=hi() : hello(a)

The error is thrown at "=" in the if condition. How to solve this. Or is there any alternative to perform this in one liner?

Use = for value assignment, but == for value comparison. — Jeronimo
– Jeronimo, Commented Jul 1, 2019 at 10:58
Notice that every function has return type. Even if there is no return in function, it has return None (or just return) behind the scenes. — Aaron_ab
– Aaron_ab, Commented Jul 1, 2019 at 11:01
The meaning of "this" at the bottom of your question is not clear. What exactly are you trying to accomplish? — John Coleman
– John Coleman, Commented Jul 1, 2019 at 11:05
Possible duplicate of stackoverflow.com/questions/2603956/… — Nivlem
– Nivlem, Commented Jul 1, 2019 at 11:10

Saeed · Accepted Answer · 2019-07-01 11:11:24Z

3

You need to create a tuple of a and b then you can compare using ==

Use this,

if (a,b)==hi() : hello(a)

Here is the full code which prints asd

def hi():
  return 10,20

def hello(a):
  if a:
    print "asd"

a,b = 10,20

if (a,b)==hi() : hello(a)

edited Jul 1, 2019 at 11:11

answered Jul 1, 2019 at 11:01

Saeed

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3 Comments

user11428585 Over a year ago

But what if the return values inside the function hi() is dynamic?.

user11428585 Over a year ago

so should I use a global tuple to have a dynamic value?

Saeed Over a year ago

I don't think you need global tuple. If the return value inside hi() function is, let's say return x,y where x and y are variables which you can set before, your if condition will simply check the actual value tuples, if they are equal or not. For example, if a,b=10,20 and x,y=5,10 then your if will evaluate to look like if (10,20)==(5,10) which will be false and hello(a) won't be executed.

abdusco · Accepted Answer · 2019-07-01 11:00:14Z

0

You can't have arbitrary expressions in an if statement, you can only use a boolean like value (something that can be interpreted as true/false).

So you need to do something like this

def hi():
  return 10,20

def hello(a):
  if a:
    print "asd"

a, b = hi() 
if a:
    hello(a)

answered Jul 1, 2019 at 11:00

abdusco

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