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Cover image for Code Smell 183 - Obsolete Comments
Maxi Contieri ⭐⭐⭐
Maxi Contieri ⭐⭐⭐

Posted on • Originally published at maximilianocontieri.com

Code Smell 183 - Obsolete Comments

Comments are a code smell. Obsolete comments are a real danger and nobody maintains what can't be executed.

TL;DR: Don't trust comments. They are dead.

Problems

  • Bad documentation

  • Maintainability

Solutions

  1. Replace comments with tests

Refactorings

Context

We know comments add almost no value to our code.

We need to restrict comments only to very important decisions.

Since most people change logic and forget to update comments they might become obsolete easily.

Sample Code

Wrong

void Widget::displayPlugin(Unit* unit)
{

    // TODO the Plugin will be modified soon, so I don't implement this right now

    if (!isVisible) {
        // hide all widgets
        return;
    }

}
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Right

void Widget::displayPlugin(Unit* unit)
{ 
    if (!isVisible) {
        return;
    }
}
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Detection

[X] Semi-Automatic

We can warn for comments in our code and try to remove them.

Exceptions

  • Very important design decisions

Tags

  • Comments

Conclusion

We need to think before adding a comment. Once It is in the codebase is beyond our control and can start to lie anytime.

Relations

Disclaimer

Code Smells are just my opinion.

Credits

Photo by Volodymyr Hryshchenko on Unsplash


Obsolete comments tend to migrate away from the code they once described. They become floating islands of irrelevance and misdirection in the code.

Bob Martin


This article is part of the CodeSmell Series.

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