Code Smell 62 - Flag Variables

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

Problems

• Readability

• Maintainability

• Coupling

Solutions

1. Use meaningful names

2. 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.

Tags

• Readability

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

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

Henry Spencer

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Comments

[Michael Currin]

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
}