Introduction to Design Patterns
Tags: webdev, beginners, design, productivity
Published: 2022-12-29 05:40:17

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## What is it ?
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.

Design patterns can be considered as a best practice that has been learned through experience and can be used to improve the design of software systems. They provide a common vocabulary for discussing design, which can be useful for communication between developers.

#### Design patterns are typically divided into three main categories:
 ***creational, structural, and behavioral patterns.***
- Creational patterns deal with object creation mechanisms, trying to create objects in a manner suitable to the situation.
- Structural patterns deal with object composition, creating relationships between objects to form larger structures. 
- Behavioral patterns focus on communication between objects, what goes on between objects and how they operate together.

Design patterns can be a powerful tool for software developers, as they provide proven solutions to common design problems and can help developers write more flexible, maintainable, and reusable code.
## Why i would use it ?
There are several reasons why you might want to use design patterns in your software development projects:

1.     To reuse successful design solutions: Design patterns provide a common vocabulary for discussing design and can be used to describe proven solutions to common design problems. By using a design pattern, you can reuse a successful design solution that has been used in other projects.
2.     To design for flexibility and maintainability: Design patterns can help you design software systems that are more flexible and easier to maintain. For example, the factory pattern allows you to create objects in a super class, but allows subclasses to alter the type of objects that will be created, which can make your system more flexible and easier to change. 
3.  To communicate effectively with other developers: Design patterns provide a common language that developers can use to communicate about design. By using design patterns, you can more effectively communicate your design ideas to other members of your development team.

4.  To improve the overall quality of your code: Using design patterns can help you write more maintainable, flexible, and reusable code, which can improve the overall quality of your software.
 
Overall, design patterns can be a useful tool in software development, as they provide proven solutions to common design problems and can help you design more flexible, maintainable, and reusable code.
## Type Of Design Patterns

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There are several design patterns that are commonly used in software development. Here is a list of some of the most popular design patterns:
   

### 1.  Singleton pattern:
 This pattern ensures that a class has only one instance, and provides a global access point to that instance.
### 2.     Factory pattern: 
This pattern provides an interface for creating objects in a super class, but allows subclasses to alter the type of objects that will be created.
### 3.     Abstract factory pattern: 
This pattern provides an interface for creating families of related or dependent objects without specifying their concrete classes.
### 4.     Builder pattern: 
This pattern separates the construction of a complex object from its representation, allowing the same construction process to create various representations.
### 5.     Prototype pattern: 
This pattern specifies the kind of objects to create using a prototypical instance, and creates new objects by copying this prototype.
### 6.     Adapter pattern: 
This pattern allows objects with incompatible interfaces to work together by wrapping the adapter in a class that follows the target interface.
### 7.     Bridge pattern: 
This pattern decouples an abstraction from its implementation, allowing the two to vary independently.
### 8.     Composite pattern: 
This pattern allows you to compose objects into tree structures and treat individual objects and compositions of objects uniformly.
### 9.     Decorator pattern: 
This pattern allows you to add new behavior to existing objects dynamically by wrapping them in an decorator object.
### 10.     Facade pattern: 
This pattern provides a simplified interface to a complex system.
### 11.     Flyweight pattern: 
This pattern reduces the cost of creating and manipulating a large number of similar objects by sharing them.
### 12.     Proxy pattern: 
This pattern provides a surrogate or placeholder for another object to control access to it.
### 13.     Chain of responsibility pattern: 
This pattern allows you to pass requests along a dynamic chain of objects until one of them handles the request.
### 14.     Command pattern: 
This pattern allows you to encapsulate actions in objects and pass them to other objects.
### 15.     Interpreter pattern: 
This pattern defines a grammatical representation for a language and an interpreter to deal with this grammar.
### 16.     Iterator pattern: 
This pattern allows you to access the elements of an object sequentially without exposing its underlying representation.
### 17.     Mediator pattern: 
This pattern allows you to reduce coupling between classes that communicate with each other by introducing a mediator object.
### 18.     Memento pattern: 
This pattern allows you to capture the internal state of an object and restore it later.
### 19.     Observer pattern: 
This pattern allows you to define a one-to-many dependency between objects so that when one object changes state, all its dependents are notified and updated automatically.
### 20.     State pattern: 
This pattern allows an object to alter its behavior when its internal state changes.
### 21.     Strategy pattern: 
This pattern allows you to define a family of algorithms, encapsulate each one, and make them interchangeable.
### 22.     Template method pattern: 
This pattern defines the skeleton of an algorithm as an abstract class, allowing subclasses to provide concrete behavior.
### 23.     Visitor pattern: 
This pattern allows you to add new behavior to existing class hierarchies without changing their code.