6.2. Inheritance Mixins
>>> class User:
... pass
>>>
>>> class Admin:
... pass
>>>
>>> class Account(User, Admin):
... pass
6.2.1. Use Case - 1
>>> class UserMixin:
... def profile_create(self): ...
... def profile_read(self): ...
... def profile_update(self): ...
... def profile_delete(self): ...
>>>
>>> class StaffMixin:
... def account_suspend(self): ...
... def account_unsuspend(self): ...
>>>
>>> class AdminMixin:
... def account_list(self): ...
... def account_create(self): ...
... def account_read(self): ...
... def account_update(self): ...
... def account_delete(self): ...
>>>
>>>
>>> class Account(UserMixin, StaffMixin, AdminMixin):
... def __init__(self, firstname, lastname):
... self.firstname = firstname
... self.lastname = lastname
>>>
>>>
>>> mark = Account('Mark', 'Watney')
6.2.2. Use Case - 2
Definition:
>>> class ContextMixin:
... extra_context = None
... def get_context_data(self, **kwargs): ...
>>>
>>> class TemplateResponseMixin:
... template_name = None
... template_engine = None
... response_class = ...
... content_type = None
... def render_to_response(self, context, **response_kwargs): ...
... def get_template_names(self): ...
>>>
>>> class View:
... http_method_names = ["get", "post", "put", "patch", "delete", "head", "options", "trace"]
... def __init__(self, **kwargs): ...
... def view_is_async(cls): ...
... def as_view(cls, **initkwargs): ...
... def setup(self, request, *args, **kwargs): ...
... def dispatch(self, request, *args, **kwargs): ...
... def http_method_not_allowed(self, request, *args, **kwargs): ...
... def options(self, request, *args, **kwargs): ...
... def _allowed_methods(self): ...
Usage:
>>> class TemplateView(TemplateResponseMixin, ContextMixin, View):
... def get(self, request, *args, **kwargs): ...
>>> class RedirectView(View):
... permanent = False
... url = None
... pattern_name = None
... query_string = False
6.2.3. 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: Inheritance Problems Decompose
# - Difficulty: easy
# - Lines: 30
# - Minutes: 5
# %% English
# 1. Refactor class `Hero` to use multiple inheritance
# 2. Name mixin classes: `HealthMixin` and `PositionMixin`
# 3. Run doctests - all must succeed
# %% Polish
# 1. Zrefaktoruj klasę `Hero` aby użyć wielodziedziczenia
# 2. Nazwij klasy domieszkowe: `HealthMixin` i `PositionMixin`
# 3. Uruchom doctesty - wszystkie muszą się powieść
# %% Tests
"""
>>> import sys; sys.tracebacklimit = 0
>>> assert sys.version_info >= (3, 9), \
'Python 3.9+ required'
>>> from random import seed; seed(0)
>>> from inspect import isclass
>>> assert isclass(Hero)
>>> assert isclass(HealthMixin)
>>> assert isclass(PositionMixin)
>>> assert issubclass(Hero, HealthMixin)
>>> assert issubclass(Hero, PositionMixin)
>>> assert hasattr(HealthMixin, 'health')
>>> assert hasattr(HealthMixin, 'is_alive')
>>> assert hasattr(HealthMixin, 'is_dead')
>>> assert hasattr(PositionMixin, 'position_x')
>>> assert hasattr(PositionMixin, 'position_y')
>>> assert hasattr(PositionMixin, 'position_set')
>>> assert hasattr(PositionMixin, 'position_change')
>>> assert hasattr(PositionMixin, 'position_get')
>>> assert hasattr(Hero, 'HEALTH_MIN')
>>> assert hasattr(Hero, 'HEALTH_MAX')
>>> assert hasattr(Hero, 'health')
>>> assert hasattr(Hero, 'position_x')
>>> assert hasattr(Hero, 'position_y')
>>> assert hasattr(Hero, 'is_alive')
>>> assert hasattr(Hero, 'is_dead')
>>> assert hasattr(Hero, 'position_set')
>>> assert hasattr(Hero, 'position_change')
>>> assert hasattr(Hero, 'position_get')
>>> watney = Hero()
>>> watney.is_alive()
True
>>> watney.position_set(x=1, y=2)
>>> watney.position_change(left=1, up=2)
>>> watney.position_get()
(0, 0)
>>> watney.position_change(right=1, down=2)
>>> watney.position_get()
(1, 2)
"""
from dataclasses import dataclass
from random import randint
from typing import ClassVar
# Refactor class `Hero` to use multiple inheritance
# Name mixin classes: `HealthMixin` and `PositionMixin`
@dataclass
class Hero:
HEALTH_MIN: ClassVar[int] = 10
HEALTH_MAX: ClassVar[int] = 20
health: int = 0
position_x: int = 0
position_y: int = 0
def position_set(self, x: int, y: int) -> None:
self.position_x = x
self.position_y = y
def position_change(self, right=0, left=0, down=0, up=0):
x = self.position_x + right - left
y = self.position_y + down - up
self.position_set(x, y)
def position_get(self) -> tuple:
return self.position_x, self.position_y
def __post_init__(self) -> None:
self.health = randint(self.HEALTH_MIN, self.HEALTH_MAX)
def is_alive(self) -> bool:
return self.health > 0
def is_dead(self) -> bool:
return self.health <= 0