public function getDirtyAttributes($names = null)
{
if ($names === null) {
$names = $this->attributes();
}
$names = array_flip($names);
$attributes = [];
if ($this->_oldAttributes === null) {
foreach ($this->_attributes as $name => $value) {
if (isset($names[$name])) {
$attributes[$name] = $value;
}
}
} else {
foreach ($this->_attributes as $name => $value) {
if (isset($names[$name]) && (!array_key_exists($name, $this->_oldAttributes) || $value !== $this->_oldAttributes[$name])) {
$attributes[$name] = $value;
}
}
}
return $attributes;
}