TL:DR; Don't leave code for future use.

Problems

• Complexity

• Coupling

Solutions

1. Remove dead code.

2. Leave covered and real tested code.

Sample Code

Wrong

<?

final class DatabaseQueryOptimizer {

  public function selectWithCriteria($tableName, $criteria) {
    //Make some optimizations manipulating criteria
  }

  private function sqlParserOptimization(SQLSentence $sqlSentence): SQLSentence {
    //Parse the SQL converting it to a string and then working with their nodes as strings and lots of regex
    //This was a very costly operation overcoming real SQL benefits.
    //But since we made too much work we decide to keep the code. 
  }  
}

Right

<?

final class DatabaseQueryOptimizer {

  public function selectWithCriteria($tableName, $criteria) {
    //Make some optimizations manipulating criteria
  } 
}

Detection

Using some mutation testing variants we can remove the dead code and see if test fails.

We need to have good coverage to rely on this solution.

Tags

• YAGNI

Conclusion

Dead code is always a problem.

We can use modern development techniques like TDD to ensure all code is alive.

Also Known as

• Speculative Generality

Relations

More info

• Exception not Found

• Wikipedia

• Refactoring.guru

Credits

Photo by Kris Mikael Krister on Unsplash

Thanks to Apoorv Tyagi for pointing this out.

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It is very hard to predict, especially the future.

Niels Bohr

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This article is part of the CodeSmell Series.

Last update: 2021/06/13