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
##__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>> |
| |
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