What is Design Pattern and How it Works? [2023]

White and blue brick wall

If you're in the world of software development, you might have heard of design patterns. In this article, we will provide you with a complete guide on design patterns, answer some commonly asked questions, and provide you with some quick tips and facts to keep in mind.

What are Design Patterns?

Design patterns refer to a repeatable solution to commonly occurring problems in software design. Design patterns provide a way to streamline the development process by offering tested, proven development paradigms. They are documented attempts to solve recurring design problems.

Simply put, design pattern is a blueprint for solving certain software design problems. These patterns enable software engineers to reuse their code and focus more on the development of unique functions. By utilizing design patterns, software engineers can accelerate the development process, increase code reliability, and reduce software development cost.

Why are Design Patterns Important?

Design patterns are important because they allow software engineers to avoid reinventing the wheel when building software. They facilitate the reuse of successful software designs and architectures, which in turn reduces the cost of development. Patterns also provide a common vocabulary for communication between software engineers.

One of the benefits of using design patterns is that it standardizes the design of software systems and promotes code reuse. By implementing these patterns, developers can create software systems that are easier to maintain, scale, and extend.

Types of Design Patterns

There are three types of design patterns: creational, structural, and behavioral.

Creational Design Patterns

Creational patterns focus on the process of object creation. These patterns provide various object creation mechanisms, which increase flexibility and reuse of existing code. The five types of creational patterns are:

  • Singleton: Ensures that only one instance of a class is created and provides a global point of access to that instance.
  • Prototype: Used to create a new object from an existing object.
  • Factory Method: Creates objects without exposing the instantiation logic to the client.
  • Abstract Factory: Provides an interface for creating families of related objects without specifying their concrete classes.
  • Builder: Used to create complex objects that have multiple parts.

Structural Design Patterns

Structural patterns focus on the composition of classes and objects. These patterns provide different ways of building objects and structures. The seven types of structural patterns are:

  • Adapter: Adapts one interface of a class to another interface the client expects.
  • Bridge: Decouples an abstraction from its implementation so that the two can vary independently.
  • Composite: Allows you to compose objects into tree structures to represent part-whole hierarchies.
  • Decorator: Dynamically adds behavior to objects.
  • Facade: Provides a unified interface to a set of interfaces in a subsystem.
  • Flyweight: Reduces the memory footprint of complex objects.
  • Proxy: Provides a surrogate or placeholder for another object to control access to it.

Behavioral Design Patterns

Behavioral patterns focus on the communication between objects. These patterns provide methods of communication between objects, and enable them to cooperate and work together. The eleven types of behavioral patterns are:

  • Chain of Responsibility: Enables an object to pass a request along a chain of processors until the request is handled.
  • Command: Turns a request into a standalone object that can be passed to an invoker object to run the request.
  • Interpreter: Defines a representation of a language grammar to enable interpretation of sentences in the language.
  • Iterator: Provides a way to access the elements of an aggregate object sequentially without exposing its underlying representation.
  • Mediator: Reduces coupling between objects by allowing them to communicate through a mediator object.
  • Memento: Captures and externalizes an object's internal state so that the object can be restored to that state later.
  • Observer: Defines a dependency between objects so that when one object changes state, all its dependents are notified and updated.
  • State: Allows an object to alter its behavior when its internal state changes.
  • Strategy: Enables the selection of an algorithm at runtime.
  • Template Method: Defines the skeleton of an algorithm in a superclass but lets subclasses override specific steps of the algorithm.
  • Visitor: Separates an algorithm from an object's structure by moving the algorithm into a separate object.

Is MVC a Design Pattern?

Shipping container pattern

The Model-View-Controller (MVC) is an architectural pattern, not a design pattern. MVC is commonly used for building user interfaces that divide the application into three interconnected components.

Design patterns, on the other hand, address various software design problems, such as object creation, composition, and communication. Design patterns are more low-level and have a narrower focus.

Quick Tips and Facts

  • The most commonly used design patterns are the Singleton, Factory Method, and Abstract Factory patterns.
  • Design patterns are language-independent and can be used with various programming languages.
  • Design patterns are not a guarantee for good software design. They are simply guidelines for dealing with particular situations.
  • It is important to correctly identify a problem before applying a design pattern to solve it.
  • Design patterns can improve the efficiency and maintainability of software systems.

Conclusion

Design patterns are a proven and effective way to streamline the software development process. They provide common solutions to recurring problems in software design. By utilizing design patterns, software engineers can write more efficient, reusable, and maintainable code.

If you're a software engineer or a developer wondering how design patterns can improve your code, we highly recommend learning about these patterns and how they can be implemented.

At Stack Interface™, we believe that design patterns are a crucial aspect of software development that all engineers should be familiar with. Keeping this in mind, we recommend incorporating design patterns into your development process if you want to improve your codebase.

For more information on design patterns and how to implement them in your software development process, please see the below references.

References

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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