PHP类与对象中的private访问控制的疑问

class bar
{
public function test() {
$this->testprivate();
$this->testpublic();
}
public function testpublic() {
echo "bar::testpublic\n";
}
private function testprivate() {
echo "bar::testprivate\n";
}
}
class foo extends bar
{
public function testpublic() {
echo "foo::testpublic\n";
}
private function testprivate() {
echo "foo::testprivate\n";
}
}
$myfoo = new foo();
$myfoo->test(); // bar::testprivate
// foo::testpublic