What is the Python Dunder Method for the “not and” Operator?

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In Python, “dunder” methods, short for “double underscore” methods, are special methods that allow developers to define the behavior of built-in operations for custom objects. For instance, when you use the + operator to add two objects, Python internally calls the __add__ method. Similarly, other operators have their corresponding dunder methods.

However, the term “not and” operator might be a bit misleading, as there isn’t a direct “not and” operator in Python.

Instead, Python provides individual operators for not, and and. But if we delve into the realm of bitwise operations, we find operators that might resemble this behavior: the bitwise NOT (~) and the bitwise AND (&).

Let’s explore the dunder methods associated with these operators.

Bitwise NOT (~) and its Dunder Method __invert__

The bitwise NOT operator flips the bits of a number. For a custom class, if you want to define or override the behavior of the ~ operator, you’d use the __invert__ method.

class BitwiseNumber:
    def __init__(self, value):
        self.value = value

    def __invert__(self):
        return BitwiseNumber(~self.value)

    def __repr__(self):
        return str(self.value)

number = BitwiseNumber(5)
print(~number)  # Outputs: -6

In the above example, the __invert__ method returns a new BitwiseNumber object with its value inverted.

Bitwise AND (&) and its Dunder Method __and__

The bitwise AND operator performs a bitwise AND operation between two numbers. For custom classes, the behavior of the & operator can be defined or overridden using the __and__ method.

class BitwiseNumber:
    def __init__(self, value):
        self.value = value

    def __and__(self, other):
        if isinstance(other, BitwiseNumber):
            return BitwiseNumber(self.value & other.value)
        return NotImplemented

    def __repr__(self):
        return str(self.value)

number1 = BitwiseNumber(5)  # Binary: 101
number2 = BitwiseNumber(3)  # Binary: 011
print(number1 & number2)    # Outputs: 1 (Binary: 001)

In this example, the __and__ method checks if the other object is an instance of BitwiseNumber and then performs a bitwise AND operation.


While there isn’t a direct “not and” operator in Python, leveraging the __invert__ and __and__ methods, you can define how the bitwise NOT and AND operations work for custom objects, respectively.