7.10. Operator Comparison¶

in - contains

7.10.1. SetUp¶

>>> from functools import reduce

7.10.2. About¶

Table 7.5. Comparison Operator Overload¶
Operator	Method
`obj == other`	`obj.__eq__(other)`
`obj != other`	`obj.__ne__(other)`

7.10.3. Object Equality¶

When you compare objects with the same fields from two different classes
Always remember to compare classes
This way you avoid bug, when both has the same fields and values
Eq Works at Both Sides

>>> class Fruit:
...     def __init__(self, name):
...         self.name = name
>>>
>>>
>>> a = Fruit('Apple')
>>> b = Fruit('Apple')
>>>
>>> a == b
False

>>> class Fruit:
...     def __init__(self, name):
...         self.name = name
...
...     def __eq__(self, other):
...         return self.name == other.name
>>>
>>>
>>> a = Fruit('Apple')
>>> b = Fruit('Apple')
>>>
>>> a == b
True

>>> class Fruit:
...     def __init__(self, name):
...         self.name = name
...
...     def __eq__(self, other):
...         return self.name == other.name
>>>
>>>
>>> class Company:
...     def __init__(self, name):
...         self.name = name
>>>
>>>
>>> a = Fruit('Apple')
>>> b = Fruit('Apple')
>>> c = Company('Apple')
>>>
>>> a == b
True
>>>
>>> a == c
True

>>> class Fruit:
...     def __init__(self, name):
...         self.name = name
...
...     def __eq__(self, other):
...         return self.__class__ is other.__class__ \
...            and self.name == other.name
>>>
>>>
>>> class Company:
...     def __init__(self, name):
...         self.name = name
>>>
>>>
>>> a = Fruit('Apple')
>>> b = Fruit('Apple')
>>> c = Company('Apple')
>>>
>>> a == b
True
>>>
>>> a == c
False

Eq Works at Both Sides:

>>> class Fruit:
...     def __init__(self, name):
...         self.name = name
>>>
>>>
>>> class Company:
...     def __init__(self, name):
...         self.name = name
...
...     def __eq__(self, other):
...         return self.__class__ is other.__class__ \
...            and self.name == other.name
>>>
>>>
>>> a = Fruit('Apple')
>>> b = Fruit('Apple')
>>> c = Company('Apple')
>>>
>>> a == b
False
>>>
>>> a == c
False