Relaxed Naming With Class Constant

Relaxed naming is the possibility to use PHP keywords as method or class constant names (for properties, the $ has allowed it for a long time).

private, protected and public were not valid class constant names, until PHP 8.3. They were eligible to be method names, though.

PHP code

<?php

class x {
    public const string private = 'protected';
}

echo x::private;

?>

Before

PHP Parse error:  syntax error, unexpected token "private", expecting "=" 

Parse error: syntax error, unexpected token "private", expecting "=" 

After

protected

PHP version change

This behavior changed in 8.3.

Error Messages

• syntax error, unexpected token “private”, expecting “=”