PHP Strict
A set of simple utilities for adding strictness to your PHP,
using facilities already built into the language.
Trait IMSoP\Strict\Properties
Declare that the list of properties in your class is complete,
and should not be modified at runtime. Eliminates the possibility
of
Trait IMSoP\Strict\StaticClass
Declare that a class consists only of static members, and should
not be constructed.
Does not make the entire class "final", but does prevent non-static descendant classes.
See also the rejected RFC https://wiki.php.net/rfc/abstract_final_class