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 Workflow Design Patterns Explained with Examples

As Large Language Models (LLMs) evolve into autonomous agents, understanding agentic workflow design patterns has…

16 hours ago

What is Data Strategy?

In today's data-driven business landscape, organizations are constantly seeking ways to harness the power of…

2 days ago

Mathematics Topics for Machine Learning Beginners

In this blog, you would get to know the essential mathematical topics you need to…

4 weeks ago

Questions to Ask When Thinking Like a Product Leader

This blog represents a list of questions you can ask when thinking like a product…

1 month ago

Three Approaches to Creating AI Agents: Code Examples

AI agents are autonomous systems combining three core components: a reasoning engine (powered by LLM),…

1 month ago

What is Embodied AI? Explained with Examples

Artificial Intelligence (AI) has evolved significantly, from its early days of symbolic reasoning to the…

3 months ago