<?php
 
class MyClass {
    public $properties = [];
 
    public function __construct($args){
        $this->properties = $args;        
    }
 
    public function __get($name) {
        if (array_key_exists($name, $this->properties)) {
            return $this->properties[$name];
        }
        return null;
    } 
}
 
$obj = new MyClass(["key1" => "value1", "key2" => "value2"]);
 
var_dump($obj->key1);
var_dump($obj->key2);
var_dump($obj->key3);

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