Why my getter (__get) is not called in PHP class? - php

Question

I have read all related question, but failed to remove the bug from my code. Please guide me about possible error in my code.
When I try to call following code, it reports Error: Call to undefined method SessionManager::close() in E:\wamp64\www\mjs-cms\private\systemcore\helper\SessionManager.php on line 22 instead of "tried to call close".
Thanks in advance.
<?php
defined('BASEPATH') OR exit('No direct script access allowed');
class SessionManager{
public function __construct() {
session_start();
}
public function is_exist($a){
return isset($_SESSION["system".$a]);
}
public function add($a,$b){
$_SESSION["system".$a]=$b;
}
public function addCookies($a,$b){
setcookie($a, $b, time() + (86400 * 30), "/"); // 86400 = 1 day
}
public function sessionKey(){
return session_id();
}
public function value($k){
if(!isset($_SESSION[$k]))
$this->close("SESSION_NOT_DEFINED".__LINE__);
return $_SESSION[$k];
}
public function __get($key)
{
echo "tried to call $key";
return get_instance()->$key;
}
}

Answer 1

__get method is for accessing undeclared properties of a class.
For calling undeclared functions is __call or __callStatic.
public function __call($method_name, $arguments)
{
echo "tried to call: $method_name";
}
If you want to use __get - you must call for undefined property. In this case it is not
SessionManager::close() // call method `close()`
It must be:
$sm = new SessionManager;
$sm->propertyName; // trying to access undefined property `propertyName` of an object
Take into consideration that
Property overloading only works in object context.
which means that trying to access static property like
SessionManager::staticProperty;
will not work with __get.