in the part where thinkphp5 is used as the site configuration item to take effect in real time

read the data in the configuration table in the app_init hook function, which can be read in all pages. My idea is to use $GLOABLS. But I see other people"s code using the v function to achieve the same effect as $GLOABLS.

$data=Db:table("config")->find();
$GLOBALS["config"]=$data;//
v("config)=$data;//

with v function code

// 
if ( ! function_exists("v")) {
    /**
     * 
     *
     * @param null   $name  
     * @param string $value 
     *
     * @return array|mixed|null|string
     */
    function v($name = null, $value = "[null]")
    {
        static $vars = [];
        if (is_null($name)) {
            return $vars;
        } else if ($value == "[null]") {
            //
            $tmp = $vars;
            foreach (explode(".", $name) as $d) {
                if (isset($tmp[$d])) {
                    $tmp = $tmp[$d];
                } else {
                    return null;
                }
            }

            return $tmp;
        } else {
            //
            $tmp = &$vars;
            foreach (explode(".", $name) as $d) {
                if ( ! isset($tmp[$d])) {
                    $tmp[$d] = [];
                }
                $tmp = &$tmp[$d];
            }

            return $tmp = $value;
        }
    }
}

I don"t quite understand how this function can implement variables that can be accessed by all files in the project. Please advise me one or two
maybe I don"t understand the scope of php enough