Code Smell 37 - Protected Attributes

Code Smell 37 - Protected Attributes

Subscribe to my newsletter and never miss my upcoming articles

Listen to this article

Protected attributes are great for encapsulating and controlling access to our properties. They might be warning us for another smell.



  1. Favor composition
  2. Don't subclassify attributes.
  3. Extract behavior to separate objects.
  4. Use traits (if available).



In languages supporting protected attributes we can avoid them by policy or have a warning of this smell.


  • Encapsulation


Protected attributes are yet another tool we should use carefully. Every decision is a smell, and we should be very careful with attributes and inheritance.


More Info

Traits on Wikipedia


Photo by Jonathan Farber on Unsplash

Subclasses shouldn’t always share all characteristics of their parent class but will do so with inheritance. This can make a program’s design less flexible. It also introduces the possibility of calling methods on subclasses that don’t make sense or that cause errors because the methods don’t apply to the subclass.

Steve Klabnik

This article is part of the CodeSmell Series.

Share this