static public function uuid($separator=true)
    {
        if (function_exists('com_create_guid')){
            return com_create_guid();
        }else{
            mt_srand((double)microtime()*10000);    //optional for php 4.2.0 and up.
            $charid = strtoupper(md5(uniqid(mt_rand(), true)));
            $hyphen = $separator ? chr(45) : '';  // "-"
            $uuid = substr($charid, 0, 8).$hyphen
            .substr($charid, 8, 4).$hyphen
            .substr($charid,12, 4).$hyphen
            .substr($charid,16, 4).$hyphen
            .substr($charid,20,12);
            //$uuid = chr(123) . $uuid .chr(125);  // "{" "}"
            return $uuid;
        }
    }
static public function uuid($separator=true)
    {
        if (function_exists('com_create_guid')){
            return com_create_guid();
        }else{
            mt_srand((double)microtime()*10000);    //optional for php 4.2.0 and up.
            $charid = strtoupper(md5(uniqid(mt_rand(), true)));
            $hyphen = $separator ? chr(45) : '';  // "-"
            $uuid = substr($charid, 0, 8).$hyphen
            .substr($charid, 8, 4).$hyphen
            .substr($charid,12, 4).$hyphen
            .substr($charid,16, 4).$hyphen
            .substr($charid,20,12);
            //$uuid = chr(123) . $uuid .chr(125);  // "{" "}"
            return $uuid;
        }
    }
static public function uuid ( $ separator = true ) { if ( function_exists ( 'com_create_guid' ) ) { return com_create_guid ( ) ; } else { mt_srand ( ( double ) microtime ( ) * 10000 ) ; //optional for php 4.2.0 and up. $ charid = strtoupper ( md5 ( uniqid ( mt_rand ( ) , true ) ) ) ; $ hyphen = $ separator ? chr ( 45 ) : '' ; // "-" $ uuid = substr ( $ charid , 0 , 8 ) . $ hyphen . substr ( $ charid , 8 , 4 ) . $ hyphen . substr ( $ charid , 12 , 4 ) . $ hyphen . substr ( $ charid , 16 , 4 ) . $ hyphen . substr ( $ charid , 20 , 12 ) ; //$uuid = chr(123) . $uuid .chr(125);  // "{" "}" return $ uuid ; } }
get uuid '315B817C-11F5-718F-F7BD-95E0E95519D0'

@param  boolean $separator if true then contain '-'
@return string
get uuid 315B817C - 11F5 - 718F - F7BD - 95E0E95519D0