Multiple Classes with Single responsibility VS Single Class with Multiple Responsibilities

While taking a session with a set of mobile developers, one of them asked a question that made many of them curious.

Why multiple classes when single class can do?

  1. The main reasoning for single class was that one would be able to save some lines of code.
  2. Also, one would be required to create just one object for multiple functionalities.

Lets look at some of the key advantages of multiple classes, each one of them having single functionality.

  • High in cohesion, and hence reduced coupling. This tends to make the class reusable.
  • Lesser costly to change than single class. Following explains the cost structure related with a change:

Let’s say a class is performing multiple different functions. Mathematically, the class can be represented as following:

 Class A = f(x) + f(y) + f(z)

Let’s say, one needs to fix a bug related with f(x). Thus, one fixed the code in the class A that performed f(x).  The code was, then, shipped to QA engineers. QA engineers used to spend, let’s say, 1hour for each function. Thus, for a change in one function he spent 3 hours.

The total cost of change is 3 X (let’s say $20/hour as rate for QA engineer)  = $60.

  • On the other hand, if there were three different classes for three different functions, the cost of change would have been just $15. (Think How?)

Thus, it makes much more sense to split functionality into different classes as the change will be less costlier than following the approach of having multiple functionality in one class. The design leading to this approach (multiple class) could also be termed as “Cost-effective” design.

Ajitesh Kumar

I have been recently working in the area of Data analytics including Data Science and Machine Learning / Deep Learning. I am also passionate about different technologies including programming languages such as Java/JEE, Javascript, Python, R, Julia, etc, and technologies such as Blockchain, mobile computing, cloud-native technologies, application security, cloud computing platforms, big data, etc. I would love to connect with you on Linkedin. Check out my latest book titled as First Principles Thinking: Building winning products using first principles thinking.

Recent Posts

Agentic Reasoning Design Patterns in AI: Examples

In recent years, artificial intelligence (AI) has evolved to include more sophisticated and capable agents,…

1 month ago

LLMs for Adaptive Learning & Personalized Education

Adaptive learning helps in tailoring learning experiences to fit the unique needs of each student.…

1 month ago

Sparse Mixture of Experts (MoE) Models: Examples

With the increasing demand for more powerful machine learning (ML) systems that can handle diverse…

2 months ago

Anxiety Disorder Detection & Machine Learning Techniques

Anxiety is a common mental health condition that affects millions of people around the world.…

2 months ago

Confounder Features & Machine Learning Models: Examples

In machine learning, confounder features or variables can significantly affect the accuracy and validity of…

2 months ago

Credit Card Fraud Detection & Machine Learning

Last updated: 26 Sept, 2024 Credit card fraud detection is a major concern for credit…

2 months ago