Commented code is a bad code smell

This is a rant about commented code.

Have you ever seen projects with many thousands of line of code that have a significant portion of the code commented out ? I am not talking about descriptive or explanatory comments about what the code does – I mean where the code block itself is commented …

Leaving the commented code in an application lowers the readability of code in the application. Today, source control systems are ubiquitous in software projects – so why do people still comment code and leave it rather than deleting it completely? It simply serves no purpose other than increasing code bloat.

We all do it of course – usually while debugging or understanding code. To discover if a piece of code is used in the application – it is sometimes easy to simply comment the code and let the compiler tell you where it is called from.

But, once we finish we should ether delete the commented code or un-comment it. Commenting code is, at best, a stop gap measure and IMHO a rank code smell indicating that you should probably create a code branch for your code for your experimentation.

It is quite tedious and frustrating to have to pick out the blocks of actual code from between the often, vast stretches, of commented code. Let us, as professional developers, develop the habit of never leaving any such code cruft in anything that we check in to a project !

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3 comments on “Commented code is a bad code smell

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