Indent With Intent

Imagine you've written the following hack to see which OS you're running.

OperatingSystem determine_os(uname: &str) {
  if (uname.contains("Darwin")) {
    return OperatingSystem.MacOS;
  } else if (uname.contains("Linux")) {
    return OperatingSystem.Linux;
  } else {
    return OperatingSystem.Unknown;
  }
}

You send it for code review, and get the following comment.

Nit: you can remove the final else.

Unfortunately, a common code review comment. But does it hold up to scrutiny?

What does it look like after applying the suggestion?

OperatingSystem determine_os(uname: &str) {
  if (uname.contains("Darwin")) {
    return OperatingSystem.MacOS;
  } else if (uname.contains("Linux")) {
    return OperatingSystem.Linux;
  }
  return OperatingSystem.Unknown;
}

By omitting the final else, we've broken the structural and visual alignment of logic that belongs to the same category.

Indentation is a visual manifestation of logical structure. Things that are alike logically and structurally should reflect that visually.

This function is effectively a tri-branch conditional return. And the code should show that as explicitly as possible. The else logically groups the code and encodes that meaning into it via structure. There's a cargo cult against using else anywhere. Don't fall for that trap.

If you're still not convinced, consider this. Would you write a switch statement like this?

switch(color) {
  case "red":
    return Color.Red;
  case "blue":
    return Color.Blue;
}

return Color.Unknown;

Or would you write it like this?

switch(color) {
  case "red":
    return Color.Red;
  case "blue":
    return Color.Blue;
  default:
    return Color.Unknown;
}