Maxi Contieri

Posted on Feb 8, 2021 • Edited on Apr 9, 2022 • Originally published at maximilianocontieri.com

Code Smell 62 - Flag Variables

#programming #oop #webdev #tutorial

Flags indicate what happened. Unless their name is too generic.

Problems

Readability
Maintainability
Coupling

Solutions

Use meaningful names
Try to avoid flags. They generate coupling.

Sample Code

Wrong

	<?

	function dummy() {

	$flag = true;

	while ($flag == true) {

	$result = checkSomething();
	if ($result) {
	$flag = false;
	}
	}
	}

view raw uselessFlag.php hosted with ❤ by GitHub

Right

	<?

	function dummy()
	{
	$atLeastOneElementWasFound = false;

	while (!$atLeastOneElementWasFound) {

	$elementSatisfies = doSomething();
	if ($elementSatisfies) {
	$atLeastOneElementWasFound = true;
	}
	}
	}

view raw declarativeFlag.php hosted with ❤ by GitHub

Detection

We can search all the code for bad named flags.

Conclusion

Flags are widespread on production code. We should restrict their usage and use clear and intention revealing names.

Relations

Code Smell 51 - Double Negatives

Maxi Contieri ・ Dec 24 '20

#codenewbie #tutorial #programming #oop

Code Smell 07 - Boolean Variables

Maxi Contieri ・ Oct 26 '20

#codenewbie #tutorial #beginners

More Info

Wikipedia

If you lie to the compiler, it will get its revenge.

Henry Spencer

Timescale – the developer's data platform for modern apps, built on PostgreSQL

Timescale Cloud is PostgreSQL optimized for speed, scale, and performance. Over 3 million IoT, AI, crypto, and dev tool apps are powered by Timescale. Try it free today! No credit card required.

Try free

Top comments (1)

Michael Currin • Feb 8 '21

You suggested to restrict usage but didn't say how or provide and example.

Can I provide an alternative without the flag? Which is shorter and more readable.

while(true) {
  $elementSatisfies = doSomething();
  if (!$elementSatisfies) {
    break;
  }
}

Or even

while(doSomething()) {
  pass
}

DEV Community