CODEWITHSUNDEEP
pythonpython-2.7python-3.x
user3603535
user3603535

Reputation: 11

how to make an operator function in python?

I need to make an operators to an object and I wonder what is the best way.

for example for the operator add

can I write this in this way?

def _add_(self,other):
   new=self.add(self,other)// can I write like that?
    return new

thanks for the help!

Upvotes: 1

Views: 142

Answers (1)

sshashank124
sshashank124

Reputation: 32189

You would use the python magic function __add__ to take care of the +:

Example:

class A():
    def __init__(self, num):
        self.num = num
    def __add__(self, other):
        return self.num + other

a = A(6)

>>> print a+5
11

For greater flexibility, you should also define __radd__, this is for the reverse addition case 5+a which would not work in the example above.

class A():
    def __init__(self, num):
        self.num = num
    def __add__(self, other):
        return self.num + other
    def __radd__(self, other):
        return self.num + other

>>> a = A(6)
>>> print 5+a
11
>>> print a+5
11

Or if you want to return as an object instead of an int, you can do it as:

class A():
    def __init__(self, num):
        self.num = num
    def __add__(self, other):
        return A(self.num + other)

a = A(5)
b = a+5
print b.num
10
print a.num
5

What has been demonstrated above is operator overloading. It overrides the built-in default methods for handling operators by letting the user define custom methods for the operators.

Here is a list you might find useful as to which operators can be overloaded

Upvotes: 6

Related Questions