DEV Community

SaptakBhoumik
SaptakBhoumik

Posted on

Operator overloading in python

Hi everyone,
In this post I want to explain the concept of operator overloading in python.

What is operator overloading?

In simple terms, it allows you to define what an operator does depending on it's argument.

Implementing it in python

Let's say that you are implementing a library to perform matrix operation. Instead of implementing a function to add 2 matrix you can overload a + operator instead. This will make your library much easier to use.

The code

class matrix:
    def __init__(self,value):
        self.value=value
    def __add__(self,other):
        result =[[0 for i in range(len(self.value[0]))] for x in range(len(self.value))]
        # iterate through rows
        for i in range(len(self.value)):   
            # iterate through columns
            for j in range(len(self.value[0])):
                result[i][j] = self.value[i][j] + other.value[i][j]
        return result

x = [[1,2,3],

    [4 ,5,6],

    [7 ,8,9]]

y = [[9,8,7],

    [6,5,4],

    [3,2,1]]        
print(matrix(x)+matrix(y))
Enter fullscreen mode Exit fullscreen mode

Breaking it down
__init__- It initializes the object. Nothing special
__add__-This is where the overloading of the + operator occurs. Within this function you have to implement how to add those numbers and that's it. It is how you overload operator in python.

Operator that can be overloaded
Binary Operators:
+ = __add__(self, other)
– = __sub__(self, other)
* = __mul__(self, other)
/ = __truediv__(self, other)
// = __floordiv__(self, other)
% = __mod__(self, other)
** = __pow__(self, other)
>> = __rshift__(self, other)
<< = __lshift__(self, other)
& = __and__(self, other)
| = __or__(self, other)
^ = __xor__(self, other)

Comparison Operators :

< = __lt__(self, other)
> = __gt__(self, other)
<= = __le__(self, other)
>= = __ge__(self, other)
== = __eq__(self, other)
!= = __ne__(self, other)

Assignment Operators :

-= = __isub__(self, other)
+= = __iadd__(self, other)
*= = __imul__(self, other)
/= = __idiv__(self, other)
//= = __ifloordev__(self, other)
%= = __imod__(self, other)
**= = __ipow__(self, other)
>>= = __irshift__(self, other)
<<= = __ilshift__(self, other)
&= = __iand__(self, other)
|= = __ior__(self, other)
^= = __ixor__(self, other)

Unary Operators:
– = __neg__(self, other)
+ = __pos__(self, other)
~ = __invert__(self, other)
This is the list of operators you can overload in python along with the name of the method you have to use

Conclusion

Operator overloading is a powerful feature of python and can be very useful however you should not misuse it because it can create confusing code that is hard to read. I hope you learned something new. If you have enjoyed this one, make sure to read my previous post
Thanks for reading <3

Discussion (2)

Collapse
free_one profile image
Michael

could you give a link to this in the python docs

Collapse
saptakbhoumik profile image
SaptakBhoumik Author

There you go :- docs.python.org/3/reference/datamo...

What I showed you is one of many different types of dunder/magic methods