other.php

<?php

require('sctwo.php');

$sctwo = new SomeTestClass();
$sctwo->vartwo = "Test var....";

echo "Test: " . $sctwo->vartwo;

?>

scone.php

<?php

class SomeTestClass 
{
  var $varone;
}

?>

sctwo.php

<?php

class SomeTestClass 
{
  var $vartwo;
}

?>

test.php

<?php

require('scone.php');

$scone = new SomeTestClass();
$scone->varone = "One...";

echo "Test: " . $scone->varone ;

?>