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Maxi Contieri ⭐⭐⭐
Maxi Contieri ⭐⭐⭐

Posted on • Updated on • Originally published at


Code Smell 46 - Repeated Code

DRY is our mantra. Teachers tell us to remove duplication. We need to go beyond.


  • Code Duplication

  • Maintainability


  1. Find repeated patterns (not repeated code).

  2. Create an abstraction.

  3. Parametrize abstraction calls.

  4. Use composition and never inheritance.

  5. Unit test new abstraction.

Sample Code




Linters can find repeated code.

There are not very good finding similar patterns.

Maybe soon machine learning will help us find such abstractions automatically.

For now, it is up to us, humans.


  • Duplication


Repeated code is always a smell.

Copying and pasting code is always a shame.

With our refactoring tools, we need to accept the duplication remove challenge trusting our tests as a safety net.


More info

Don't repeat


Photo by Sid Balachandran on Unsplash

Copy and paste is a design error.

David Parnas

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