Static Variable Accepts Functioncalls As Default¶

Static variables are actually variables: as such, they can be inited with the result of a functioncall.

Until PHP 8.3, their default values were using static constant expression, built around constants and operators.

Since PHP 8.3, it is possible to also set their first value as a function or method call.

Properties and parameters are not allowed to use these expressions: they must be valid at compile time.

PHP code¶

<?php

function foo() {
     static $x = goo(1);

     return ++$x;
}

function goo() {
     return 3;
}

echo foo();
echo foo();

?>

Before¶

PHP Fatal error:  Constant expression contains invalid operations in /codes/staticVariableWithArbitraryDefault.php on line 4

Fatal error: Constant expression contains invalid operations in /codes/staticVariableWithArbitraryDefault.php on line 4

After¶

PHP version change¶

This behavior changed in 8.3