PhpBrew\Command\ExtensionCommand\InstallCommand::arguments PHP Method

    public function arguments($args)
    {
        $args->add('extensions')->suggestions(function () {
            $extdir = Config::getBuildDir() . '/' . Config::getCurrentPhpName() . '/ext';
            return array_filter(scandir($extdir), function ($d) use($extdir) {
                return $d != '.' && $d != '..' && is_dir($extdir . DIRECTORY_SEPARATOR . $d);
            });
        });
    }