Code Smell 118 — Return False

Checking for a boolean condition to return a boolean value is awkward

Photo by Morgan Housel on Unsplash

TL;DR: Don’t return explicit booleans. Most boolean usages are code smells.

Problems

• Declarativeness
• Ninja Code
• Implementative solutions

Solutions

1. Return a boolean proposition instead of checking a negation.
2. Answer must be a business logic formula, not an algorithm.

Context

When dealing with boolean formulas, it is more readable to show a business boolean formula than introduce a negated IF clause.

Programmers tend to return accidental implementative solutions instead of real business rules.

Sample Code

Wrong

function canWeMoveOn() {
  if (work.hasPendingTasks())
    return false;
  else
    return true;
}

Right

function canWeMoveOn() {
  return !work.hasPendingTasks();
}

Detection

[X] Automatic

Based on syntax trees, we can safely refactor the code.

Tags

• Boolean

Conclusion

Beware of returning booleans.

After the return, you will need an If statement which is also a code smell.

Relations

Code Smell 115 — Return True

Code Smell 97 — Error Messages Without Empathy

Code Smell 24 — Boolean Coercions

Code Smell 62 — Flag Variables

Code Smell 102 — Arrow Code

Code Smell 51 — Double Negatives

More Info

• How to Get Rid of Annoying Ifs Forever

Credits

Thanks to Nico K. for this suggestion.

It’s not at all important to get it right the first time. It’s vitally important to get it right the last time.

Andrew Hunt

Software Engineering Great Quotes

This article is part of the CodeSmell Series.

How to Find the Stinky parts of your Code