CS343 Blog Post for Week of October 16

SOLID Design Principles Explained: The Single Responsibility Principle

This week, I wanted to further research software design principles and guidelines. In my past coding projects, there wasn’t any set framework or model I would stick to when writing my code. This led to creating classes that depended on each other too closely, and methods that attempted to accomplish too many tasks at once. To create better functioning software, I’m going to need to learn the best design practices to abide by at the outset of the project.

A popular set of design principles among software professionals are the SOLID design principles. Named by Robert C. Martin, SOLID is an acronym for 5 design principles that lend themselves to efficient, functional software. These 5 principles are:

1. Single Responsibility Principle
2. Open / Closed Principle
3. Liskov Substitution Principle
4. Interface Segregation Principle
5. Dependency Inversion

This blog post from the Stackify website focuses on the Single Responsibility Principle and its role in the software development process. Robert C. Martin describes the Single Responsibility Principle as “A class should have one, and only one, reason to change.” Abiding by this principle may help avoid unintended consequences from future updates to the software, as fewer interactions may break as a result of changes to the code.

Even small-scale software projects will likely change significantly over time, and keeping the Single Responsibility Principle in mind will prevent your classes from being encumbered by unnecessary dependencies on each other. If a single class is called upon by many other classes within your software, changes to that class may break the functionality of any classes dependent on that parent class.

Making an effort to keep components of your program independent of one another also has the benefit of keeping your project simple for a human to understand and explain. When a piece of software can be understood by the developer or team of developers working on it, the flow of productivity is so much greater since fewer effort is being spent on deciphering how the software functions. Updates and new features can also be released more quickly and consistently when the structure of the program is easier to modify without compromising the interactions between its components.

Abiding by the Single Responsibility Principle does not mean only creating classes with a singular function, however. This approach can lead to the same problem of too many classes becoming dependent on a singular parent class, and unnecessarily complicates the structure of your program.