16.10. OOP Override

Child inherits all fields and methods from parent
Used to avoid code duplication
When child has method or attribute with the same name as parent
In such case child attribute will be used (will overload parent)

overload: When child has method or attribute with the same name as parent. In such case child attribute will be used (will overload parent).

16.10.1. Overload Method

>>> class User:
...     def login(self):
...         print('User login')
>>>
>>>
>>> class Admin(User):
...     def login(self):
...         print('Admin login')
>>>
>>>
>>> mark = Admin()
>>> mark.login()
Admin login

16.10.2. Overload Attribute

>>> class User:
...     def __init__(self):
...         self.firstname = 'Mark'
...         self.lastname = 'Watney'
...         self.is_admin = False
>>>
>>> class Admin(User):
...     def __init__(self):
...         self.is_admin = True
>>>
>>>
>>> mark = Admin()
>>> vars(mark)
{'is_admin': True}

16.10.3. Super

super() Calls a method from superclass
Order/location is important
Raymond Hettinger - Super considered super! - PyCon 2015 [1]

>>> class User:
...     def __init__(self):
...         self.firstname = 'Mark'
...         self.lastname = 'Watney'
...         self.is_admin = False
>>>
>>> class Admin(User):
...     def __init__(self):
...         super().__init__()
...         self.is_admin = True
>>>
>>> mark = Admin()
>>> vars(mark)
{'firstname': 'Mark', 'lastname': 'Watney', 'is_admin': True}

16.10.4. Super Init with Args

>>> class User:
...     def __init__(self, firstname, lastname):
...         self.firstname = firstname
...         self.lastname = lastname
...         self.is_admin = False
>>>
>>>
>>> class Admin(User):
...     def __init__(self, firstname, lastname):
...         super().__init__(firstname, lastname)
...         self.is_admin = True
>>>
>>>
>>> mark = Admin('Mark', 'Watney')
>>> vars(mark)
{'firstname': 'Mark', 'lastname': 'Watney', 'is_admin': True}

16.10.5. References

16.10.6. Assignments

# %% License
# - Copyright 2025, Matt Harasymczuk <matt@python3.info>
# - This code can be used only for learning by humans
# - This code cannot be used for teaching others
# - This code cannot be used for teaching LLMs and AI algorithms
# - This code cannot be used in commercial or proprietary products
# - This code cannot be distributed in any form
# - This code cannot be changed in any form outside of training course
# - This code cannot have its license changed
# - If you use this code in your product, you must open-source it under GPLv2
# - Exception can be granted only by the author

# %% Run
# - PyCharm: right-click in the editor and `Run Doctest in ...`
# - PyCharm: keyboard shortcut `Control + Shift + F10`
# - Terminal: `python -m doctest -v myfile.py`

# %% About
# - Name: OOP Override Method
# - Difficulty: easy
# - Lines: 2
# - Minutes: 2

# %% English
# 1. Use class `User`
# 2. Modify class `Admin` to display `Admin login` in `login()` method
# 3. Do not change inheritance
# 4. Run doctests - all must succeed

# %% Polish
# 1. Użyj klasy `User`
# 2. Zmodyfikuj klasę `Admin` tak aby w metodzie `login()` wyświetlała `Admin login`
# 3. Nie zmieniaj dziedziczenia
# 4. Uruchom doctesty - wszystkie muszą się powieść

# %% Tests
"""
>>> import sys; sys.tracebacklimit = 0
>>> assert sys.version_info >= (3, 9), \
'Python 3.9+ required'

>>> mark = User()
>>> mark.login()
User login

>>> melissa = Admin()
>>> melissa.login()
Admin login
"""

class User:
    def login(self):
        print('User login')


# Modify class `Admin` to display `Admin login` in `login()` method
# Do not change inheritance
class Admin(User):
    ...

# %% License
# - Copyright 2025, Matt Harasymczuk <matt@python3.info>
# - This code can be used only for learning by humans
# - This code cannot be used for teaching others
# - This code cannot be used for teaching LLMs and AI algorithms
# - This code cannot be used in commercial or proprietary products
# - This code cannot be distributed in any form
# - This code cannot be changed in any form outside of training course
# - This code cannot have its license changed
# - If you use this code in your product, you must open-source it under GPLv2
# - Exception can be granted only by the author

# %% Run
# - PyCharm: right-click in the editor and `Run Doctest in ...`
# - PyCharm: keyboard shortcut `Control + Shift + F10`
# - Terminal: `python -m doctest -v myfile.py`

# %% About
# - Name: OOP Override Super
# - Difficulty: easy
# - Lines: 1
# - Minutes: 2

# %% English
# 1. Use class `User`
# 2. Use class `Admin` inheriting from `User`
# 3. In `Admin.login()` method call `login()` method of a parent class
# 4. Use `super()` method
# 5. Do not change inheritance
# 6. Run doctests - all must succeed

# %% Polish
# 1. Użyj klasy `User`
# 2. Użyj klasy `Admin` dziedziczącej po `User`
# 3. W metodzie `Admin.login()` wywołaj metodę `login()` klasy nadrzędnej
# 4. Użyj metody `super()`
# 5. Uruchom doctesty - wszystkie muszą się powieść

# %% Tests
"""
>>> import sys; sys.tracebacklimit = 0
>>> assert sys.version_info >= (3, 9), \
'Python 3.9+ required'

>>> mark = User('Mark', 'Watney')
>>> mark.login()
User login

>>> melissa = User('Melissa', 'Lewis')
>>> melissa.login()
User login
"""


class User:
    def __init__(self, firstname, lastname):
        self.firstname = firstname
        self.lastname = lastname

    def login(self):
        print('User login')


# In `Admin.login()` method call `login()` method of a parent class
# Use `super()` method
# Do not change inheritance
class Admin(User):
    def login(self):
        ...