Design patterns are time-tested solutions that help developers create reliable, flexible, and scalable software. They are templates based on general principles and architectural solutions that can be used in different situations. Their role is to help us design programs in a more organized manner, make code more reusable, and simplify system maintenance.
The history of design patterns dates back to the late 1970s with the work of Erich Gamma, Richard Helm, Ralph Johnson, and John Vlissides, known as the Gang of Four (GoF). They collected their experience and knowledge in the field of object-oriented programming in the book “Design Patterns: Elements of Reusable Object-Oriented Software, published in 1994.
For example, let’s consider what typical programming tasks can be solved using patterns:
- The Strategy: This pattern allows you to define a family of algorithms, encapsulate each of them, and make them interchangeable, for example, in the development of a game where the player can choose different attack or defense strategies;
- Adapter pattern: used to transform the interface of one class into the interface of another. For example, when integrating a new library that has a different interface into an existing application.
- Observer pattern: allows you to establish a one-to-many relationship between objects. If one object changes its state, all those who are subscribed to it receive an automatic notification and are updated. An example of use is notifications in the user interface;
- The use of these and other patterns helps to effectively solve typical tasks in software development, making the code more flexible, maintainable, and scalable.
There are three main types of patterns:
- Creational Patterns. They provide mechanisms for creating objects, making it possible to make the system independent of how they are created, composed, and presented. Examples: Singleton, Factory Method, Abstract Factory;
- Structural Patterns. Define ways to compose classes or objects to form larger structures. Examples include: Adapter, Decorator, Facade;
- Behavioral Patterns. They denote algorithms and ways of interacting between objects, providing more efficient and flexible interaction. Examples: Observer, Strategy, Command.
Studying and mastering design patterns is an investment in the future. Knowing the patterns allows developers to write more reliable, efficient, and readable code, which in turn improves the quality and maintainability of the software.
Before deciding which design pattern is best suited for the task at hand, you should carefully study the requirements of the task itself. Find out which parts of the system need to be changed and identify specific problems that can be solved by applying different patterns.
Don’t forget about the specifics of your project. Take a look at its architecture, components, and connections between them. Choose patterns that best suit the unique features of your system.
Don’t forget about the SOLID principles. They are not just a theory, they are tools that provide flexibility and maintainability of the code.
The context of pattern usage also plays an important role. Think about what use cases a particular pattern will be most effective in. This will help you adapt it to your needs. When exploring alternatives, don’t forget to compare their advantages and limitations.