In this repo we will design and build maintainable, extensible and robust python packages, each package is a type of design pattern with its UML diagram.

Classification of patterns

• Creational patterns provide object creation mechanisms that increase flexibility and reuse of existing code.

• Structural patterns explain how to assemble objects and classes into larger structures, while keeping these structures flexible and efficient.

• Behavioral patterns take care of effective communication and the assignment of responsibilities between objects.

• Observer

Is a behavioral design pattern that lets you define a subscription mechanism to notify multiple objects about any events that happen to the object they’re observing. The repo contains below codes.

• online market place example.
• newsletter example.

• Strategy

Is a behavioral design pattern that lets you define a family of algorithms, put each of them into a separate class, and make their objects interchangeable. Below code examples are included:

• e-commerce
• notification service
• message_formatter

• Template Method

Is a behavioral design pattern that defines the skeleton of an algorithm in the superclass but lets subclasses override specific steps of the algorithm without changing its structure. Below code examples are included:

• cv_report_generation
• message_formatter
• video_preset

• Memento

Is a behavioral design pattern that lets you save and restore the previous state of an object without revealing the details of its implementation. It separates dependency between History, Object State and Context. Below code examples are included:

• text_editor
• canvas

• Visitor

Is a behavioral design pattern that allows adding new behaviors to existing class hierarchy without altering any existing code. Below code examples are included:

• schedule_management
• document_processing_system

• Iterator

Is a behavioral design pattern that lets you traverse elements of a collection without exposing its underlying representation.

• employee_hierarchy_iterator
• profiles_iterator

• Chain of Responsibility

Is behavioral design pattern that allows passing request along the chain of potential handlers until one of them handles request. Below code examples are included:

• middleware_handler (Strategy + Template Method + Chain of Responsibility are applied in this exercise)
• data_processing_chain_handler

• State

Is a behavioral design pattern that allows an object to change the behavior when its internal state changes. Below code examples are included:

• order_management
• project_management

• Mediator

Is a behavioral design pattern that lets you reduce chaotic dependencies between objects. The pattern restricts direct communications between the objects and forces them to collaborate only via a mediator object. Below code examples are included:

• chat_mediator
• air_traffic_controller_mediator

• Command

Is behavioral design pattern that converts requests or simple operations into objects. Below code examples are included:

• smart_home_application

• Adapter

Is a structural design pattern that allows objects with incompatible interfaces to collaborate. It does this by providing a wrapper, or "adapter," that translates one interface to another. Below code examples are included:

• weather_application

• Bridge

Is a structural design pattern that lets you split a large class or a set of closely related classes into two separate hierarchies—abstraction and implementation—which can be developed independently of each other. Below code examples are included:

• streaming_video_platform

• Composite

Is a structural design pattern that lets you compose objects into tree structures and then work with these structures as if they were individual objects. Below code examples are included:

• org_hierarchy

• Decorator

Is a structural pattern that allows adding new behaviors to objects dynamically by placing them inside special wrapper objects, called decorators. Below code examples are included:

• beverage_ordering_system

• Facade

Is a structural design pattern that provides a simplified interface to a library, a framework, or any other complex set of classes. Below code examples are included:

• travel_booking_system

• Proxy

Is a structural design pattern that lets you provide a substitute or placeholder for another object. A proxy controls access to the original object, allowing you to perform something either before or after the request gets through to the original object. Below code examples are included:

• json_caching_proxy

• Flyweight

Is a structural design pattern that lets you fit more objects into the available amount of RAM by sharing common parts of state between multiple objects instead of keeping all of the data in each object.

• Builder

Is a creational design pattern that lets you construct complex objects step by step. The pattern allows you to produce different types and representations of an object using the same construction code. Below code examples are included:

• notifications_system

• Singleton

Is a creational design pattern that lets you ensure that a class has only one instance, while providing a global access point to this instance. Below code examples are included:

• logging_system

• Prototype

Is a creational design pattern that allows cloning objects, even complex ones, without coupling to their specific classes. Below code examples are included:

• marketing_material_designer

• Factory Method

Is a creational design pattern that provides an interface for creating objects in a superclass, but allows subclasses to alter the type of objects that will be created. Below code examples are included:

• payment_processor

• Abstract Factory

Is a creational design pattern that lets you produce families of related objects without specifying their concrete classes. Below code examples are included:

• global_payment_processor