['filter' => FILTER_CALLBACK, 'options' => [self::class, 'checkEmptySet']] ); protected function generate() : void { $pages = ScreenshotMgr::getPages($this->_get['all'], $nPages); $this->result = 'ssm_screenshotPages = '.Util::toJSON($pages).";\n"; $this->result .= 'ssm_numPagesFound = '.$nPages.';'; } }