8.3. Operator Membership

• in

• not in

8.3.1. SetUp

>>> from dataclasses import dataclass

8.3.2. Example

• item in obj -> obj.__contains__(item)

>>> @dataclass
... class Vector:
...     x: int
...     y: int
...
...     def __contains__(self, item): ...  # item in obj

# Use Case - 1

0 in [1, 2, 3] # False

class list:

def __contains__(self, item):

for element in self.values:

if element == item:

return True

return False

# Use Case - 2

'x' in 'Python' # False

class str:

def __contains__(self, item):

for letter in self.value:

if letter == item:

return True

return False