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Cover image for Code Smell 62 - Flag Variables
Maxi Contieri
Maxi Contieri

Posted on • Edited on • Originally published at maximilianocontieri.com

1

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;
}
}
}

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

More Info

Wikipedia


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

Henry Spencer


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Top comments (1)

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michaelcurrin profile image
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;
  }
}
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Or even

while(doSomething()) {
  pass
}
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