PHP - Detailed explanation of Traversable interface

Traversable is used to detect whether a class can be traversed using foreach. This is an internal engine interface that cannot be implemented in PHP scripts. In actual programming, we use the Iterator interface or IteratorAggregate interface to implement traversal.

Interface summary:

Traversable {
}

An important use of Traversable is to determine whether a class can be traversed. The following is the official example:

<?php
    if( !is_array( $items ) && !$items instanceof Traversable )
        //Throw exception here
?>

It should be noted that arrays and objects can be traversed through foreach, but they do not implement the Traversable interface, so Example that is not Traversable:

<?php
$array=[1,2,3];
$obj = (object) $array;
var_dump($array instanceof \Traversable);
var_dump($obj instanceof \Traversable);
?>

The above code output:

<small>boolean</small><span>false</span>

rrree added:

When the class does not implement the Iterator interface or the IteratorAggregate interface, executing foreach traversal will output all the visible properties it can access

The above introduces the detailed explanation of the PHP - Traversable interface, including the relevant aspects. I hope it will be helpful to friends who are interested in PHP tutorials.