Skip to main content

Change Preventers

Welcome to the "Change Preventers" category. As the name suggests, these are the code smells that make your software resistant to change.

When you try to add a feature or fix a bug, do you feel like you're fighting the code? Do you have to touch a dozen files just to change a simple label? Or do you find that changing one class breaks five unrelated features? If so, you're likely dealing with Change Preventers.

"For the things we have to learn before we can do them, we learn by doing them." — Aristotle

Software is meant to be "soft"—malleable and easy to change. These smells harden your codebase, making it brittle and difficult to maintain.

Smell List​

Here are the classic smells in this category:

Divergent Change​

Occurs when one class is changed for many different reasons. It violates the Single Responsibility Principle.

Shotgun Surgery​

Occurs when a single change requires you to make many small edits to many different classes. It's the opposite of Divergent Change.

Parallel Inheritance Hierarchies​

Occurs when every time you make a subclass of one class, you also have to make a subclass of another.

Combinatorial Explosion​

Occurs when a hierarchy of classes explodes in size because it tries to cover every combination of independent features using inheritance.

In this section, we will explore each of these smells in detail, understand why they happen, and learn how to refactor them away to make your code easier to change.