Design Patterns
Published: 2023-05-08 02:55:22

# Introduction

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What are design patterns?

Design patterns, or design patterns, are reusable solutions to common problems that arise during software development. They are proven and tested solutions that help developers create cleaner, more flexible and maintainable code.

Design patterns provide a set of guidelines and abstractions that can be applied to different situations to solve specific problems. They are not ready-to-use snippets of code, but concepts and ideas that can be implemented according to the needs of each project.

There are several types of design patterns, which can be categorized into three main groups:

- Creation Patterns: These patterns deal with the creation of objects, providing flexible mechanisms for creating instances of classes. Some examples include the Factory Method, Abstract Factory, Singleton, and Builder pattern.

- Structural Patterns: These patterns deal with composing classes and objects to form larger structures. They help ensure that classes and objects work together efficiently. Some examples include the Adapter, Decorator, Composite, and Proxy pattern.

- Behavioral Patterns: These patterns deal with the interaction between objects and the distribution of responsibilities between them. They are useful for defining how objects communicate and interact with each other. Some examples include the Observer pattern, Strategy, Template Method and Command.

Below are some design patterns:

1. [Singleton Design Pattern](https://dev.to/israellopes/singleton-design-pattern-1-535c):  This pattern is used to ensure that a class has only one instance and provides a global point of access to that instance.

2. [Factory Design Pattern](https://dev.to/israellopes/factory-design-pattern-2-3jci): The Factory pattern is used to create objects without specifying the exact class of the object to be created. This provides an abstraction and flexibility in creating objects.

3. Observer Design Pattern: This pattern is used to implement the event and notification system, where an object (observer) maintains a list of other objects (observed) and is automatically notified of any state change in these objects.

4. Strategy Design Pattern: The Strategy pattern allows you to define a family of algorithms, encapsulate each one of them and make them interchangeable. This allows the algorithm to be selected at runtime based on requirements.

5. Decorator Design Pattern: The Decorator pattern is used to dynamically add functionality to an object. It allows extending the functionalities of an object without having to modify its structure.

6. Composite Design Pattern: The Composite pattern is used to create hierarchical tree structures. It lets you treat individual objects and collections of objects uniformly.

7. MVC Design Pattern (Model-View-Controller): The MVC pattern is used to separate business logic (Model), data presentation (View) and user interaction (Controller). This helps maintain an organized structure and makes the code easier to maintain and evolve.

8. DAO (Data Access Object) Design Pattern: The DAO pattern is used to separate data access logic from business code. It provides an abstraction for interacting with the database, allowing easy switching of data storage technologies without affecting the rest of the code.

11. Builder Design Pattern: Used to build complex objects step by step, allowing different representations of the same object.

12. Prototype Design Pattern: Allows the creation of new objects by cloning an existing object, avoiding the creation of several subclasses.

13. Adapter Design Pattern: Used to allow classes with incompatible interfaces to work together through an intermediate adapter.

14. Proxy Design Pattern: Provides a surrogate or surrogate for another object to control access to it.

15. Facade Design Pattern: Provides a simplified interface for a complex set of subsystems, making them easier to use.

16. Template Method Design Pattern: Defines the structure of an algorithm in a superclass, allowing subclasses to override specific algorithm steps.

17. Command Design Pattern: Encapsulates a request as an object, allowing you to parameterize clients with different requests and queue or log requests.

18. Iterator Design Pattern: Provide a uniform way to access the elements of a collection, without exposing its underlying implementation.

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