Design patterns in computer science are reusable templates used to solve common problems in software design. These patterns provide standardized solutions that can be applied to various programming scenarios, making the development process more efficient and effective. There are different types of design patterns that are used in computer science, and in this article, we will explore two of the most commonly used ones.

1. Creational Patterns

Creational patterns focus on the creation of objects and how they can be created in a way that is flexible, efficient, and reusable. These patterns are useful in scenarios where the type of object needed to be created is dynamic or complex. The following are two examples of creational patterns.

a. Factory Pattern

The factory pattern is one of the most widely used creational patterns. It is used to create objects without specifying the exact class of an object that needs to be created. The pattern delegates the creation of objects to a separate class, known as the factory, which decides the type of object to be created based on the input provided. This allows for flexibility in object creation, as the client does not need to know the exact class of the object but can simply request it from the factory.

Let’s take an example of a pizza making application. The user can select different types of pizza, and the application will create the respective pizza object using the factory pattern. This way, the client does not need to know how each type of pizza is created; they can simply request it from the factory, which will create the object and return it to the client.

b. Singleton Pattern

The singleton pattern is used to ensure that only one instance of a class is created. This is useful in situations where multiple instances of the same object can cause issues or lead to increased memory consumption. The pattern restricts the creation of objects to a single global instance, which can be accessed by other classes. This ensures that there is only one point of access to the object throughout the application.

For instance, in a banking application, there can be only one instance of the AccountManager class, which handles all the account-related operations. This ensures that there are no duplicate accounts created, and all the transactions and operations are handled by a single instance of the AccountManager, reducing any potential errors or discrepancies.

2. Structural Patterns

Structural patterns focus on how classes and objects can be structured to form larger, more complex structures while keeping the system flexible and efficient. These patterns help in managing the relationships between different objects, making it easier to modify and maintain them in the future. The following are two examples of structural patterns.

a. Adapter Pattern

The adapter pattern is used to convert the interface of one class into another interface that clients expect. This is useful when two classes with incompatible interfaces need to work together. The pattern creates an adapter class that acts as a bridge between the two classes, allowing them to communicate and work together seamlessly.

One example of this pattern is in a music player application, where the application might need to play music files in various formats, such as MP3, WAV, or FLAC. Instead of implementing separate classes for each format, an adapter class can be used to convert the format to a common interface, which can be played by the music player.

b. Decorator Pattern

The decorator pattern is used to add additional behavior or features to an existing class without modifying its structure. This is helpful when we want to add new functionality to a class without altering its initial functionality. The pattern achieves this by wrapping the original class with a decorator class, which provides the additional functionality.

For example, in a car rental application, different types of car models can be decorated with additional features such as GPS, child seats, or Wi-Fi. These additional features can be added to the basic car model, without changing its core functionality, using the decorator pattern.

In conclusion, design patterns are essential in computer science as they provide solutions to common problems in software design. By using these patterns, developers can save time and effort by reusing proven solutions rather than reinventing the wheel. The two types of design patterns discussed in this article, creational and structural patterns, are just a few examples of the numerous patterns used in computer science. By understanding and implementing these patterns, developers can write more efficient and maintainable code in their projects.