Niels Notes

This page is read only. You can view the source, but not change it. Ask your administrator if you think this is wrong.
====== Inheritance ======

Inheritence is very tight coupling. Should be used with care as complex inheritance hierachies can make maintence very complicated. 
Try not to go deeper than 1 level of inheritance.  


====== Abstraction ======

===== Abstract base classes =====
Concept similar to interfaces, its a contract for sub classes. 

[[https://docs.python.org/3/glossary.html#term-abstract-base-class | Term abstract base class]]

[[https://docs.python.org/3/library/abc.html | Abstract base class ]]


===== Protocol classes =====

Defines a interface by defining the properties and functions a class can adhere to. Its more close to duck typing. 
Does not rely on inheritance. In runtime the interpreter checks if all the members match. 

Protocols allow for finer granularity (interface segregation), more protocols can be combined in a class before it becomes messy as there is less tight coupling in code.


===== Multiple inheritance =====

Python supports [[https://docs.python.org/3/tutorial/classes.html#multiple-inheritance|multiple inheritance]]. So a class can have multiple parent classes. The [[https://docs.python.org/3/howto/mro.html#python-2-3-mro|method resolution order]] (left to right by defined clases) is important to take into account as it defines which method in parent class gets called if the same method exists in multiple classes.

The multiple inheritance feature is also named mixins as you mix multiple types of classes actually multiple inheritance tree's together. 

When using mixins you need to know the implementation details of classes to figure out a resolution order that will work. So the class structure can become complex and hard to work with. 

[[https://arjancodes.com/about/ | Arjan ]] advises against using mixins, and when used the parent classes should only have methods so that initialisation issues (think of resolution order) with parameters are avoided. 

Mixin classes should not have instance variables. 

So its powerfull but try to avoid and use with care as it will get complicated.  

According to [[https://www.pythontutorial.net/python-oop/python-mixin/ | Python Mixin (Pythontutorial.net)]] a mixin class can be seen as the interface concept but with implementation. // "A mixin bundles a set of methods for reuse" //
Niels Notes

User Tools

Site Tools

Page Tools
