Software-Design-Pattern

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• In software engineering, a design pattern is a general repeatable solution to a commonly occurring problem in software design.

• A design pattern isn't a finished design that can be transformed directly into code.

• It is a description or template for how to solve a problem that can be used in many different situations.

Creational Patterns

In software engineering, creational design patterns are design patterns that deal with object creation mechanisms, trying to create objects in a manner suitable to the situation. The basic form of object creation could result in design problems or added complexity to the design.

• Creational design patterns solve this problem by somehow controlling this object creation.

• Creational design patterns are composed of two dominant ideas.

  • One is encapsulating knowledge about which concrete classes the system use.
  • Another is hiding how instances of these concrete classes are created and combined.

• Creational design patterns are further categorized into Object-creational patterns and Class-creational patterns

• where Object-creational patterns deal with Object creation and Class-creational patterns deal with Class-instantiation.

• In greater details, Object-creational patterns defer part of its object creation to another object, while Class-creational patterns defer its objection creation to subclasses.

• Five well-known design patterns that are parts of creational patterns are listed as follows:

index	Type	Pattern Name	Usage
1	Creational	The Factory Pattern	which allows a class to defer instantiation to subclasses.
2	Creational	The Singleton Pattern	which ensures that a class only has one instance, and provides a global point of access to it.
3	Creational	The Prototype Pattern	which specifies the kind of object to create using a prototypical instance, and creates new objects by cloning this prototype.
4	Creational	The Builder Pattern	which separates the construction of a complex object from its representation so that the same construction process can create different representation
5	Creational	The Abstract Factory Pattern	which provides an interface for creating related or dependent objects without specifying the objects' concrete classes.

Structural Pattern

index	Type	Pattern Name	Usage
6	Structural	The Proxy Pattern
7	Structural	The Decorator Pattern
8	Structural	The Adapter Pattern	The Adapter pattern is a structural design pattern that allows objects with incompatible interfaces to work together by creating a middleman called an adapter. The adapter acts as a translator or a bridge between the two incompatible interfaces, enabling them to interact seamlessly.
9	Structural	The Facade Pattern
10	Structural	The Flyweight Pattern
11	Structural	The Composite Pattern
12	Structural	The Bridge Pattern	Decouple an abstraction from its implementation, so the 2 can vary independently.

Behavioral Design Patterns

In software engineering, behavioral design patterns are design patterns that identify common communication patterns between objects and realize these patterns.

• By doing so, these patterns increase flexibility in carrying out this communication.

• Behavioral patterns influence how state and behavior flow through a system.

• By optimizing how state and behavior are transferred and modified, you can simplify, optimize, and increase the maintainabilty of an application.

index	Type	Pattern Name	Usage
13	Behavioral	The Visitor Pattern	A way to separate an algorithm from an object
14	Behavioral	The Observer Pattern	also known as Publish/Subscribe or Event Listener. Objects register to observe an event that may be raised by another object
15	Behavioral	The Pub-Sub Pattern	also known as observer or Event Listener. Objects register to observe an event that may be raised by another object
16	Behavioral	The Strategy (Policy) Pattern	Algorithms can be selected on the fly
17	Behavioral	The Template method Pattern	Describes the program skeleton of a program
18	Behavioral	The Command Pattern	Command objects encapsulate an action and its parameters
19	Behavioral	The Iterator Pattern	Iterators are used to access the elements of an aggregate object sequentially without exposing its underlying representation
20	Behavioral	The Memento Pattern	Provides the ability to restore an object to its previous state (rollback)
21	Behavioral	The State Pattern	A clean way for an object to partially change its type at runtime
23	Behavioral	The Mediator Pattern	Provides a unified interface to a set of interfaces in a subsystem
24	Behavioral	The Chain of Responsibility Pattern	Command objects are handled or passed on to other objects by logic-containing processing objects
25	Behavioral	The interpreter Pattern	Implement a specialized computer language to rapidly solve a specific set of problems

Other Patterns

index	Type	Pattern Name	Usage
26	Creational	The Simple factory Pattern
27	Creational	The Null object Pattern
28	Architectural	The MVC Model-View-Controller Pattern
29	Architectural	The MVVM Model-View View-Model Pattern
30	Architectural	The MVP Model-View-Presenter Pattern
31	Data Management & Architectural	The CQRS Command Query Responsibiity Segregation Pattern
32	Data Management	The Cache-Aside Pattern
33	Data Management	The Event Sourcing Pattern
34	Data Management	The Index Table Pattern
35	Data Management	The Meteralized View Pattern
35	Data Management	The Sharding Pattern