array_map(function($obj){return $obj->getId();}, $array);
例
<?php
class Hi
{
protected $_id = 0;
public function getId()
{
return $this->_id;
}
public function setId($id)
{
$this->_id = $id;
}
}
$hi = new Hi;
$hi3 = clone $hi2 = clone $hi;
$hi->setId(1);
$hi2->setId(2);
$hi3->setId(3);
$hiList = array($hi, $hi2, $hi3);
$map = array_map(function($obj){return $obj->getId();}, $hiList);
var_dump($map);
#array(3) {
# [0] =>
# int(1)
# [1] =>
# int(2)
# [2] =>
# int(3)
#}
もっと簡単な書き方無いかな