Question

Predict the output of the following program. Also state which concept of OOP is being implemented?

def sum(x, y, z):
        print "sum= ", x+y+z
def sum(a, b):
       print "sum= ", a+b
sum(10, 20)
sum(10, 20, 30)

Answer 1

Python 3 update: print "..." must be written as print("...").

Trace:

1. The second definition of sum(a, b) overwrites sum(x, y, z).
2. Therefore, sum(10, 20) prints the sum of two values.
3. sum(10, 20, 30) causes an error because the active definition accepts only two arguments.

sum=  30
TypeError: sum() takes 2 positional arguments but 3 were given

The program attempts to implement function overloading, a form of polymorphism, but Python does not support it through repeated function definitions.