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<?php interface proxy {} trait assertFinal { private function assertFinal() { if (is_subclass_of($this, __CLASS__, false) && !$this instanceof proxy) { trigger_error('Nein! Class is final!', E_USER_NOTICE); } } } class finalfoo { use assertFinal; public function __construct() { $this->assertFinal(); } } class fooproxy extends finalfoo implements proxy { } class naughtyfoo extends finalfoo { } echo "new finalfoo: "; try {new finalfoo; echo "yes";} catch (\Exception $e) { echo "no"; } echo "\n"; echo "new fooproxy: "; try {new fooproxy; echo "yes";} catch (\Exception $e) { echo "no"; } echo "\n"; echo "new naughtyfoo: "; try {new naughtyfoo; echo "yes";} catch (\Exception $e) { echo "no"; } echo "\n";

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