[SOLVED] PHP 8 how to concisely increment dynamically generated variables

PHP 8 how to concisely increment dynamically generated variables

PHP 8 raised the Notice to a Warning that an unset variable/array key is worked on.

PHP 7.4:

// Below would create a variable and set it to 0 + 1
// Below would generate a Notice level error.
$_SESSION['dynamic']['var']++;

PHP 8+:

// Below would create a variable and set it to 0 + 1
// Below would create a warning level error that variable does not exist. 
$_SESSION['dynamic']['var']++;

Question:

With a dynamically generated variable (in the broadest sense; a variable or an array element value) such as a $_SESSION key value, how can we maintain the current action but prevent the Warning being issued. Hopefully without needing to add loads of extra code bloat.

The only way I can think of is

$_SESSION['dynamic']['var'] = ($_SESSION['dynamic']['var']??0)+1;

Which is a pretty big bloat of code from ++ to ($var??0)+1.

This seems to entirely negate the whole shortcut of ++ and -- convenient increment/decrement operators. There is no mention of this on the PHP manual pages.

Solution

In PHP 8, you can use the null coalescing operator (??) along with the nullsafe operator (?->) to concisely auto-increment dynamically generated variables within an array. This allows you to handle unset variables gracefully without raising warnings.

 $_SESSION['dynamic']['var'] ??= 0;
 $_SESSION['dynamic']['var']++;