namaste/stubs/testReferences.php

<?php
/*
 * this stub tests the ability to reference different class objects, via a generic class member, and still have the
 * IDE access the member functions and variables of the assigned class without generating warnings or errors.
 *
 * 01-07-20     mks     original coding
 */

class bar
{
    public int $y;

    public function __construct()
    {
        $this->y = 0;
    }

    public function changeY(int $newValue): bool
    {
        if ($newValue == $this->y) return false;
        $this->y = $newValue;
        return true;
    }
}

class foo
{
    public int $x;
    public object $copy;

    public function __construct()
    {
        $this->x = 1;
        $this->copy = new stdClass();
    }

    public function changeX(int $newValue = 1): bool
    {
        if ($newValue == $this->x) return false;
        $this->x = $newValue;
        return true;
    }
}

$original = new foo();

echo 'Value of original->x: ' . $original->x . PHP_EOL;
echo 'Value of original->x was ' . ($original->changeX(10)) ? '' : 'not ';
echo 'changed.' . PHP_EOL;

// assign the reference
$original->copy =& $original;

echo 'Value of copy->x ' . $original->copy->changeX(10) ? '' : 'not ';
echo 'changed.' . PHP_EOL;

echo 'value of original->copy->x: ' . $original->copy->x . PHP_EOL;

// reassign the object $original->copy to the class object $argle
$objectTwo = new bar();
$original->copy =& $objectTwo;
// note that even though $original->copy is decl as type object, we can still assign another object, of type argle
// to the member AND access that member's functions without generating a warning!
if ($original->copy->changeY(10))
    echo 'original->copy value changed!' . PHP_EOL;
else
    echo 'original->copy unchanged' . PHP_EOL;

echo 'value of original->copy->y: ' . $original->copy->y . PHP_EOL;