Design patterns are essential in software engineering because they provide tried and tested fixes for frequent issues and encourage best practices. Developers can produce applications that are more scalable, reliable, and maintainable by utilising design patterns. In this tutorial we will try to go through software engineering best practices related to design patterns, including advice on how to utilise them effectively as well as real-world examples of how they’ve been applied.
What is meant by Design Pattern ?
Reusable fixes for persistent issues in software design are known as design patterns. They act as models that may be used to solve design problems in a variety of contexts. We need to understand that design patterns are usually not language specific. These patterns can be customised to fit any language. They support developers in following industry best practices and preventing them from reinventing the wheel.
Types of Design Patterns
We can broadly categorise any design patterns into three types:
- Creational Pattern: The patterns under this category usually work with object generation methods, attempting to create objects in a situation-appropriate way. Typical patterns of creation include:
- Singleton: This pattern guarantees that a class has a single instance and offers a global access point for it.
- Factory Method: This specifies an interface required for the object creation, but allows subclasses to modify the kind of object that is created.
- Builders: This allows for the creation of several representations using the same construction process by separating the development of a complicated item from its representation.
- Structural Patterns: These patterns deal with object composition, making sure that a system doesn’t have to alter as a whole if one component changes.
- Adapter: This transforms a class’s interface into a different interface that customers expect, enabling mismatched interfaces to coexist.
- Decorator: Adds new functionality to an object dynamically by enclosing it in a custom wrapper object that includes the new functionality.
- Facade: Offers a simplified interface to a complex subsystem.
- Behavioural Patterns: These patterns deal with algorithms and the assignment of responsibilities amongst objects.
- Observer: Creates a one-to-many dependency between objects, ensuring that when one object changes state, all of its dependents are automatically notified and changed.
- Strategy: Defines a set of algorithms, encapsulates each one, and makes them interchangeable. Strategy allows the algorithm to alter independently of the clients that use it.
- Command: This allows for the parameterisation of clients with queues, requests, and operations by encapsulating a request as an object.
Best Practices for Using Design Patterns
- Problem Understanding and Planning: Using a specific design patterns involves deep and thorough understanding of the problem statement we are trying to solve. We would not want to use any specific design patterns just because we know it, but only if it is actually required to make the solution optimal.
- Following the S.O.L.I.D Principles: Design patterns usually aligns with what SOLID principles (Single Responsibility, Open/Closed, Liskov Substitution, Interface Segregation, Dependency Inversion) says. Following these principles during implementing design patterns can lead to more maintainable and scalable code. We will discuss about SOLID principles in some other tutorial.
- Document Your Design: Proper documentation needs to be maintained on why a design pattern is chosen and developed upon. This helps other developers in the team understand better the logic behind the design decisions.