Php OOP-函数未定义？

我正在尝试OOP，最近它对我不好。这是我的班级：

class db {

protected $host = "";
protected $dbname = "";
protected $user = "";
protected $pass = "";

function execute($query, $parameters, $usefetch) {

    $dsn = "mysql:host=$this->host;dbname=$this->dbname";
    $pdo = new PDO($dsn,$this->user,$this->pass);

    $pdo->setAttribute(PDO::ATTR_EMULATE_PREPARES, false);
    $pdo->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);

    try {
        $statement = $pdo->prepare($query);
        $statement->execute($parameters);

        if($usefetch) {
            $result = $statement->fetchAll(PDO::FETCH_ASSOC);
            return $result;
        } else { 
            return SUCCESS; 
        }
    }

catch(PDOException $ex) { return $ex; }

}

function __get($var) {
    return $this->$var;
}

}

当我尝试定义它并调用函数“execute”时，我得到以下错误：

致命错误：未捕获错误：调用中未定义的函数execute（） /var/www/html/api/classes/sessions.php:49堆栈跟踪：#0 /var/www/html/index.php（3）：抛出require_once（）#1{main} /var/www/html/api/classes/sessions.php，第49行

下面是我如何尝试调用它（调试）

---

我不明白为什么会发生这种错误。这可能与我的php配置有关吗？（它不会执行，即使我让dbexecute执行它自己的函数而不是对象）

发生的事情是

var\u dump（）

试图将字符串

$db

与

execute（）的输出连接起来

在全局范围内运行。

您有一个连接

，在这里您应该有

->

。应该是：

$db->execute("SELECT * FROM sessions", [], true)

而不是：

// This is a typo concatenation OR you may be temporarily confused ;) with
// a Javascript object which does use the period for object/method
$db.execute("SELECT * FROM sessions", [], true))

---

尝试

$db->

而不是

$db.

：

$db->执行（…yada，yada，yada

-\uuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuD@Rasclatt在另一个类中，我试图调用$db->execute（），但它说$db未定义；在全局范围内。因此，您需要

类会话{public function}构造（db$db，$token）{…等

然后执行

$Session=new Session（new db，$token）；

// This is a typo concatenation OR you may be temporarily confused ;) with
// a Javascript object which does use the period for object/method
$db.execute("SELECT * FROM sessions", [], true))