call method without parenthesis in python

Question

what modification i would need to do in the below function computeDifference to get result printed in the console, instead of object message.

i know i need to add parenthesis () to call function to get the result printed in the console, but is there any other way to print the result?

class Difference1:
    def __init__(self, a):
        self.__elements = a

    def computeDifference(self):
        self.difference =  max(self.__elements)- min(self.__elements)
        return self.difference

a = [5,8,9,22,2]
c = Difference1(a)
print(c.computeDifference)

score 10 · Accepted Answer · answered Nov 08 '18 at 10:13

Make it a property

class Difference1:
@property
def computeDifference(self):
   ...

print(c.computeDifference)

However, I would change the name to difference. The idea of a property is that you shouldn't know or care whether the value is computed at that time or is stored as an attribute of the object. See uniform access principle.

Peter Wood · Answer 2 · 2022-07-23T23:07:29.453

3

You could add a magic function:

class Difference1:
    ...
    def __str__(self):
        return str(self.computeDifference())
    ...

>>> a = [5,8,9,22,2]
>>> c = Difference1(a)
>>> print(c)
20

edited Jul 23 '22 at 23:07

answered Nov 08 '18 at 10:19

Peter Wood

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1

I got a '__str__ returned non-string (type int)' error. Not sure why? – Tom J Jul 23 '22 at 22:53
1

@TomJ updated to use `str` on the integer return value from `computeDifference` – Peter Wood Jul 23 '22 at 23:08

call method without parenthesis in python

2 Answers2