Strange things, static variables can not be assigned value! Solution Ideas

Strange things, static variables can not be assigned value!
The procedure is as follows:
Class Dbmanage {
public static $siteInfo; Site information

/**
* Default Execution
*/

function __construct () {
$domainKey = Strtolower ($_server[' server_name ');
$domainKey = Str_ireplace ("www.", "", $domainKey);
Self:: $siteInfo = Dbmanage::getsiteinfo ($domainKey);
}

public static function Getsiteinfo ($domain) {
Self:: $siteInfo = $_cookie["Site"]; if (Empty (self:: $siteInfo) | | self:: $siteInfo ["domain"]! = $domain) {
$sql = "SELECT * from Site_config where domain= ' {$domain} '";
Self:: $siteInfo = Self::queryarray ($sql);
Self::setcookie (self:: $siteInfo, "site");
}
Return self:: $siteInfo;
}
}

The problem is in the Scarlet Letter line. Obviously $_cookie["site" has data, but self:: $siteInfo is always empty. Would you please help me see what the reason is?

------Solution--------------------
How do You know self:: $siteInfo always empty???


------Solution--------------------
Self:: $siteInfo = $_cookie["Site"]; if (Empty (self:: $siteInfo) | | self:: $siteInfo ["domain"]! = $domain) {


You can use $_cookie["site" To assign a value, and then $siteinfo["domain" in a moment.

is $_cookie["Site" or $siteinfo an array? Where does domain come from?
------Solution--------------------
Self:: $siteInfo = $_cookie["Site"];//is this value an array?
if (self:: $siteInfo) | | self:: $siteInfo ["domain"]! = $domain)//You output a value within the condition to see if there is any execution, you know?

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