What are the 4 Main Types of Patterns Used in Design? [2023]

are the 4 main types of pattern used in design? Stack Interface

Design patterns are essential tools in software development that help solve recurring problems and provide solutions that have been tried and tested. They are reusable solutions to commonly occurring problems in software design. In this article, we will explore the four main types of patterns used in design and discuss their applications and benefits.

Table of Contents

  • Introduction
  • Creational Patterns
    • Singleton Pattern
    • Factory Pattern
    • Builder Pattern
  • Structural Patterns
    • Adapter Pattern
    • Decorator Pattern
    • Composite Pattern
    • Proxy Pattern
  • Behavioral Patterns
    • Observer Pattern
    • Strategy Pattern
    • Chain of Responsibility Pattern
  • Architectural Patterns
    • Model-View-Controller (MVC) Pattern
    • Model-View-ViewModel (MVVM) Pattern
    • Layered Architecture Pattern
  • FAQ
  • Quick Tips and Facts
  • Useful Links
  • Reference Links

Introduction

In software development, design patterns provide a structured and proven way to solve commonly recurring problems. They allow developers to build upon the collective knowledge and experiences of other developers, resulting in more efficient and maintainable code. In this article, we'll explore the four main types of design patterns: creational, structural, behavioral, and architectural patterns. Each type serves a specific purpose and has its own set of advantages and use cases.

Creational Patterns

Creational patterns focus on object creation mechanisms, providing flexibility in creating objects while hiding the creation logic.

Singleton Pattern

The Singleton pattern ensures that a class has only one instance and provides a global point of access to it. It is commonly used for resources that are expensive to create or when a single instance should be shared across the application.

Key features of the Singleton pattern:

  • Single instance: It guarantees that only one instance of a class exists.
  • Global access: The Singleton instance is globally accessible.

Some use cases for the Singleton pattern include managing database connections, logging systems, and thread pools.

Factory Pattern

The Factory pattern provides an interface for creating objects, but lets subclasses decide which class to instantiate. It encapsulates object creation and decouples it from the client code, making it easier to maintain and extend.

Key features of the Factory pattern:

  • Interface-based object creation: It uses an interface or abstract class to define object creation methods.
  • Decoupling: The client code is decoupled from the specific classes it creates.

The Factory pattern is commonly used in scenarios where the client code doesn't need to know the exact class it is creating. It promotes loose coupling and enables easier testing and extensibility.

Builder Pattern

The Builder pattern separates the construction of a complex object from its representation, allowing the same construction process to create different representations. It provides a step-by-step approach to construct objects, typically used when the creation process involves multiple steps or complex logic.

Key features of the Builder pattern:

  • Step-by-step construction: It provides a step-by-step process to construct objects.
  • Separation of concerns: Construction logic is separated from the object's representation.

The Builder pattern is beneficial when dealing with complex object creation, such as creating a customizable user interface with different configuration options.

Structural Patterns

Structural patterns focus on composing objects and classes into larger structures while keeping the structures flexible and efficient.

Adapter Pattern

The Adapter pattern allows objects with incompatible interfaces to work together by providing a common interface. It acts as a bridge between two incompatible interfaces, making them compatible without changing their existing code.

Key features of the Adapter pattern:

  • Interface compatibility: It provides a common interface to interact with incompatible objects.
  • No changes to existing code: The pattern allows objects with incompatible interfaces to work together without modifying their code.

The Adapter pattern is commonly used when integrating legacy code with new systems, or when consuming third-party libraries with different interfaces.

Decorator Pattern

The Decorator pattern attaches additional responsibilities to an object dynamically. It provides a flexible alternative to subclassing for extending functionality without modifying existing code.

Key features of the Decorator pattern:

  • Dynamic behavior extension: Additional responsibilities are added at runtime.
  • No changes to existing code: The pattern allows behavior extension without modifying core classes.

The Decorator pattern is useful for adding functionality to existing objects, such as adding new behaviors to graphical shapes or enhancing the functionality of a component.

Composite Pattern

The Composite pattern composes objects into tree structures to represent part-whole hierarchies. It allows clients to treat individual objects and compositions uniformly, making the structure more manageable.

Key features of the Composite pattern:

  • Hierarchy representation: Objects can be composed into tree structures.
  • Uniform treatment: The pattern allows treating individual objects and compositions uniformly.

The Composite pattern is commonly used in scenarios where the client needs to represent part-whole hierarchies, such as representing a file system or creating user interface components.

Proxy Pattern

The Proxy pattern provides a surrogate or placeholder for another object to control its access. It adds an additional layer of indirection between the client and the target object, allowing for additional functionality or access control.

Key features of the Proxy pattern:

  • Controlled access: The proxy controls access to the target object.
  • Additional functionality: The proxy can add additional functionality before or after accessing the target object.

The Proxy pattern is beneficial when there is a need for access control, separation of concerns, or the ability to perform additional operations before accessing the target object.

Behavioral Patterns

Behavioral patterns focus on communication between objects and how they interact and distribute responsibilities.

Observer Pattern

The Observer pattern defines a one-to-many dependency between objects, where when one object changes state, all its dependents are notified and updated automatically. It enables loose coupling between objects, allowing for more flexibility when managing complex relationships.

Key features of the Observer pattern:

  • Publish-subscribe model: Objects can subscribe to receive notifications.
  • Loose coupling: Objects are decoupled from one another and only depend on a common interface.

The Observer pattern is widely used in event-driven architectures and user interface frameworks, where changes in one object need to be propagated to multiple dependent objects.

Strategy Pattern

The Strategy pattern encapsulates interchangeable algorithms within a family and enables clients to switch between different strategies dynamically. It promotes flexibility and allows the algorithms to vary independently from clients that use them.

Key features of the Strategy pattern:

  • Interchangeable algorithms: The pattern encapsulates different algorithms and makes them interchangeable.
  • Runtime strategy selection: Clients can switch strategies dynamically.

The Strategy pattern is useful when multiple algorithms are available to solve a problem, and the choice of an algorithm depends on runtime conditions or client preferences.

Chain of Responsibility Pattern

The Chain of Responsibility pattern creates a chain of objects to handle a request, giving each object in the chain the opportunity to handle the request or pass it to the next object in the chain. It decouples senders and receivers, providing flexibility in dynamically assigning responsibilities.

Key features of the Chain of Responsibility pattern:

  • Request handling chain: Objects form a chain to handle requests.
  • Flexible assignment of responsibilities: Responsibilities can be dynamically assigned.

The Chain of Responsibility pattern is effective when multiple objects can handle a request, and the exact object that handles the request is determined at runtime.

Architectural Patterns

Architectural patterns provide guidelines for organizing the structure and relationships of components in a system, ensuring scalability, maintainability, and reusability.

Model-View-Controller (MVC) Pattern

The Model-View-Controller (MVC) pattern separates an application into three interconnected components: the model, the view, and the controller. It provides a clear separation of concerns, making the application more modular and easier to maintain.

Key features of the MVC pattern:

  • Separation of concerns: The pattern separates the responsibilities of data management (model), user interface (view), and user input handling (controller).
  • Flexibility and reusability: Components can be modified or replaced independently.

The MVC pattern is widely used in web applications and graphical user interfaces, enabling developers to create maintainable and scalable applications.

Model-View-ViewModel (MVVM) Pattern

The Model-View-ViewModel (MVVM) pattern is an evolution of the MVC pattern, specifically designed for modern user interfaces. It introduces a ViewModel layer, allowing for a more streamlined data flow between the model and the view.

Key features of the MVVM pattern:

  • Two-way data binding: Changes in the view are automatically propagated to the ViewModel, and updates in the ViewModel are automatically reflected in the view.
  • Separation of concerns: The pattern separates the responsibilities of data management (model), user interface (view), and data manipulation (viewModel).

The MVVM pattern is commonly used in frameworks like Angular and Knockout.js, facilitating the development of rich and responsive user interfaces.

Layered Architecture Pattern

The Layered Architecture pattern divides an application into different layers, each responsible for a specific set of functionalities. It promotes separation of concerns, modularization, and maintainability by enforcing a hierarchical structure.

Key features of the Layered Architecture pattern:

  • Hierarchical structure: The application is divided into layers, each with its own responsibilities.
  • Modularity and maintainability: Components within layers can be modified or replaced independently.

The Layered Architecture pattern is widely adopted in enterprise applications, where clear separation of concerns and scalability are crucial.

FAQ

What are the 3 types of patterns?

The three types of patterns used in software design are:

  1. Creational Patterns: These patterns focus on object creation mechanisms, providing flexibility in creating objects while hiding the creation logic.
  2. Structural Patterns: Structural patterns focus on composing objects and classes into larger structures while keeping the structures flexible and efficient.
  3. Behavioral Patterns: Behavioral patterns focus on communication between objects and how they interact and distribute responsibilities.

What are the four essential elements of a design pattern?

The four essential elements of a design pattern are:

  1. Pattern Name: A descriptive name that identifies and categorizes the pattern.
  2. Problem: A clear description of the problem the pattern aims to solve.
  3. Solution: A description of the solution and how it solves the problem.
  4. Consequences: The benefits, trade-offs, and potential side-effects of using the pattern.

How many types of design patterns are there?

There are 23 widely recognized design patterns categorized into four types: creational patterns, structural patterns, behavioral patterns, and architectural patterns. Each type serves a specific purpose and provides guidance for addressing different aspects of software design.

Quick Tips and Facts

  • Design patterns help solve common problems in software development and promote reusable and maintainable code.
  • Each design pattern has its own specific purpose and use cases.
  • Understanding and applying design patterns improves code quality and scalability.
  • Design patterns are not limited to specific programming languages and can be implemented in various contexts.

Now that you have a better understanding of the four main types of design patterns, you can apply them to your own software development projects. Remember, design patterns are tools that assist in solving common problems and improving the quality of your code. Experiment, practice, and continuously learn to become a master of design patterns.

Jacob
Jacob

Jacob is a software engineer with over 2 decades of experience in the field. His experience ranges from working in fortune 500 retailers, to software startups as diverse as the the medical or gaming industries. He has full stack experience and has even developed a number of successful mobile apps and games.

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