Make your PHP object available foreach and modify the properties with Private

Play it when you are bored.
Traversing an object is actually just traversing a specific array type attribute in the object.
After PHP5, you can directly foreach, but the private members of the class cannot be accessed.
The object-oriented principle also does not allow class members to be directly accessed from the outside.

/*
 * @class Sample
 * @remark The traversal object is actually just an array in the variable object; to enable the object to be traversed, the iterator interface needs to be implemented
 */
class Sample implements iterator
{
 private $v1 = '123';

 private $v2 = 'abc';

 private $v3 = array( 1, 2, 3 );

 public function rewind()
 {
 / *
 * get_object_vars Check the manual for this function to see its functions
 * Here, the Sample object implements the defined attributes instead of the dynamically generated attributes $data into an array,
 * Assign the group to $data
 * /
 $this->data = get_object_vars ( $this );

 /*
 * Point the cursor in the iterator interface to the first element of $data
 */
 reset( $this->data );
 }

 public function current() { return current( $this->data ); }

 public function key() { return key( $this->data ); }

 public function next() { return next( $this->data ); }

 public function valid() { return ( $this->current() !== false ); }

}

$s = new Sample();

foreach( $s as $k=>$v ){ echo $k.'='.$v.'';}