OOP design pattern in - Python language ?

This is one of the another article in "do I know ?" series. Where we would see different important object oriented design patten details and it's possible implementation.

Creational Patterns

Singleton Pattern Ref =>
- It returns only one object for all set of call.
- There is always a doubt of can create real singleton in python ?
- Ans - https://stackoverflow.com/questions/55860871/restricting-creation-of-object-in-a-singleton-class-using-constructor-in-python
- Implementation : https://github.com/sughosneo/dsalgo/tree/master/src/design_patterns/singleton
Factory Pattern Ref =>
- Below example also shows how different object gets created
- Implementation : https://github.com/sughosneo/dsalgo/tree/master/src/design_patterns/factory
Abstract Factory Pattern Ref =>
NULL Object Pattern Ref =>
- Instead of using repetitive NULL object check we can use this Null object pattern during creation of object.
- Implementation : https://github.com/sughosneo/dsalgo/tree/master/src/design_patterns/null

Structural Patterns

Adapter Pattern Ref =>
- Adapter pattern lets you wrap an otherwise incompatible object in an adapter to make it compatible with another class.
- Adapter pattern works as a bridge between two incompatible interfaces
- Implementation : https://github.com/sughosneo/dsalgo/tree/master/src/design_patterns/adapter
Decorator Pattern Ref =>
- Decorating one function call without making any code changes.
- There are 2 types of it - function and class decorator
- Implementation : https://github.com/sughosneo/dsalgo/tree/master/src/design_patterns/decorator
Facade Pattern Ref =>
- Facade pattern provides a simplified interface to a complex subsystem.
- One good example would be "When a computer starts up, it involves the work of cpu, memory, hard drive, etc. To make it easy to use for users, we can add a facade which wrap the complexity of the task, and provide one simple interface instead."
- Implementation : https://github.com/sughosneo/dsalgo/tree/master/src/design_patterns/facade

Behavioral Patterns

Observer Pattern Ref =>
- Define a one-to-many dependency between objects so that when one object changes state, all its dependents are notified and updated automatically.
- This pattern is useful event driven programming to notify the state changed to multiple objects.
- Implementation : https://github.com/sughosneo/dsalgo/tree/master/src/design_patterns/observer
Strategy Pattern Ref =>