php按路径选择数组

Question

我可以得到帮助以了解这是否可行吗？

我想动态选择数组。

例如，

$oj = (object)['A' => (object)['B' => (object)['C' => (object)['D' => []]]]]

$E = 'A'
$oj->$E // this will work

$E = 'A->B'  
$oj->$E // this will not work

除了写完整路径还能做什么？或者请告诉我这是否可能，或者是否有我可以引用的示例？

$oj[A][B][C][D]     <---NO
$oj->A->B->C->D     <---NO

$E = A->B->C->D    
$oj->E              <--What I want   


Question Update: 

$oj->E = 'Store something'  <-What I want, then will store into $oj.

//So E here is not pick up the value of D, but the path of D;

非常感谢。

Answer 1

可以通过->展开路径，部分路径跟踪对象:

function getPath($obj,$path) {
  foreach(explode('->',$path) as $part) $obj = $obj->$part;
  return $obj;
}

例子

$oj = (object)['A' => (object)['B' => (object)['C' => (object)['D' => []]]]];
$E = 'A->B->C->D';
getPath($oj,$E);

如果你也想写，你可以用 eval 来写，但很简单:

eval("\$tgt=&\$oj->$E;"); // $tgt is the adress of $oj->A->B->C->D->E
print_r($tgt); // original value of $oj->A->B->C->D->E
$tgt = "foo"; 
print_r($oj); // $oj->A->B->C->D->E = "foo"