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Problems
Deep Hierarchies
Subclassification for Code Reuse
Readability
Low Cohesion
High Coupling
Solutions
Favor composition over inheritance.
Refactor deep hierarchies.
Sample Code
Wrong
Right
Detection
Any linter can check for suspects against a max depth threshold.
Tags
- Hierarchy
Conclusion
Many novice programmers reuse code through hierarchies. This brings high coupled and low cohesive hierarchies.
Johnson and Foote established in their paper this was actually a good design recipe back in 1988. We have learned a lot from there.
We must refactor and flatten those classes.
Relations

Code Smell 11 - Subclassification for Code Reuse
Maxi Contieri ・ Oct 30 '20 ・ 1 min read
More info
Hierarchies should be deep by Johnson and Foote
An error arises from treating object variables (instance variables) as if they were data attributes and then creating your hierarchy based on shared attributes. Always create hierarchies based on shared behaviors, side.
David West
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