Operator related magic methods

There are too many magic methods related to operators. J will roughly list the following two categories:

1. Comparison operators

##__cmp__(self, other)if This method returns a negative number, indicating self < other; Returns a positive number, indicating self > other; Returns 0, indicating self == other. It is strongly not recommended to define __cmp__. Instead, it is best to define __lt__, __eq__ and other methods separately to implement the comparison function. __cmp__ is deprecated in Python3. __eq__(self, other)Defines the behavior of the comparison operator ==__ne__(self, other )Defines the behavior of comparison operator !=__lt__(self, other) Defines the behavior of comparison operator <__gt__(self, other)Defines the behavior of the comparison operator>__le__(self, other) Defines the behavior of the comparison operator <= __ge__(self, other) Defines the behavior of the comparison operator >=

You can understand it by looking at a simple example:

#!/usr/bin/env python3
# -*- coding: UTF-8 -*-
class Number(object):
    def __init__(self, value):
        self.value = value
    def __eq__(self, other):
        print('__eq__')
        return self.value == other.value
    def __ne__(self, other):
        print('__ne__')
        return self.value != other.value
    def __lt__(self, other):
        print('__lt__')
        return self.value < other.value
    def __gt__(self, other):
        print('__gt__')
        return self.value > other.value
    def __le__(self, other):
        print('__le__')
        return self.value <= other.value
    def __ge__(self, other):
        print('__ge__')
        return self.value >= other.value
if __name__ == '__main__':
    num1 = Number(2)
    num2 = Number(3)
    print('num1 == num2 ? --------> {} \n'.format(num1 == num2))
    print('num1 != num2 ? --------> {} \n'.format(num1 == num2))
    print('num1 < num2 ? --------> {} \n'.format(num1 < num2))
    print('num1 > num2 ? --------> {} \n'.format(num1 > num2))
    print('num1 <= num2 ? --------> {} \n'.format(num1 <= num2))
    print('num1 >= num2 ? --------> {} \n'.format(num1 >= num2))

The output result is:

__eq__
num1 == num2 ? --------> False
__eq__
num1 != num2 ? --------> False
__lt__
num1 < num2 ? --------> True
__gt__
num1 > num2 ? --------> False
__le__
num1 <= num2 ? --------> True
__ge__
num1 >= num2 ? --------> False

2. Arithmetic operator

Magic method	Description

##__and__(self, other) Implements bit operations&__or__(self, other) Implements bit operations`__xor__(self, other) Implemented bit operations^

Magic Method	Instructions
__add__(self, other)	Implements the addition operation
__sub__(self, other)	Implements the subtraction operation
__mul__(self, other)	Implements the multiplication operation
__floordiv__( self, other)	Implements the // operator
___div__(self, other)	Implements the / operator. This method is available in Python3 Deprecated. The reason is that in Python3, division defaults to true division
__truediv__(self, other)	implements true division. Only if you declare from __future__ import division This method will take effect
__mod__(self, other)	Implements the % operator and remainder operation
__divmod__(self, other)	Implements the divmod() built-in function
__pow__(self, other)	Implements the ** operation. Nth power operation
__lshift__(self, other)	implements bit operation<<
__rshift__( self, other)	Implements bit operations>>

Next Section