Code Smell 51 - Double Negatives

Code Smell 51 - Double Negatives

Not operator is our friend. Not not operator is not our friend.

TL;DR: Avoid double negatives in boolean expressions

Problems

  • Readability

Solutions

  1. Name your variables, methods and classes with positive names.

Sample Code

Wrong

if ( !work.isNotFinished() )

Right

if ( work.isDone() )

Detection

This is a semantic smell. We need to detect it on code reviews.

We can tell linters to check for Regular Expressions like !not or !isNot etc as a warning.

Tags

  • Readability

Conclusion

Double negation is a very basic rule we learn as junior developers.

There are lots of production systems filled with this smell.

We need to trust our test coverage and make safe renames and other refactors.

Relations

More info

Credits

Photo by Daniel Herron on Unsplash


It’s harder to read code than to write it.

Joel Spolsky



This article is part of the CodeSmell Series.

Last update: 2021/06/11