Registry::register( string $type, SimplePie\class-string $class, bool $legacy = false ): bool

112    public function register(string $type, $class, bool $legacy = false)113    {114        if (array_key_exists($type, $this->legacyTypes)) {115            // trigger_error(sprintf('"%s"(): Using argument #1 ($type) with value "%s" is deprecated since SimplePie 1.8.0, use class-string "%s" instead.', __METHOD__, $type, $this->legacyTypes[$type]), \E_USER_DEPRECATED);116 117            $type = $this->legacyTypes[$type];118        }119 120        if (!array_key_exists($type, $this->default)) {121            return false;122        }123 124        if (!class_exists($class)) {125            return false;126        }127 128        /** @var string */129        $base_class = $this->default[$type];130 131        if (!is_subclass_of($class, $base_class)) {132            return false;133        }134 135        $this->classes[$type] = $class;136 137        if ($legacy) {138            $this->legacy[] = $class;139        }140 141        return true;142    }