循环变量变量，非法字符串偏移量

I keep getting

Warning: Illegal string offset 'type' in ... on line ...

I've tried following the answers here Illegal string offset Warning PHP

by doing something like

if(isset($_POST['type_'.$i]))
     $$T['type'] = $_POST['type_'.$i];

but it still gives errors, I think it might have something to do with variable variables (it's the first time I am using them. Below is my code:

for($i = 1; $i <= 15; $i++){
    $T = 'T'.$i;

    $$T['type'] = $_POST['type_'.$i];
    $$T['hidden'] = $_POST['hidden_'.$i];
    $$T['require'] = $_POST['require_'.$i];
    if(isset($_POST['question_'.$i.'_list']))
        $$T['list'] = $_POST['quesiton_'.$i.'_list'];
}

I won't like to create arrays T1, T2 ... T15, with the following values ['type'], ['hidden'], ['require'], ['list'].

The problem is one of precedence. $T['type'] is resolved first, and then used as the variable name for $___.

Since $T is a string, ['type'] is an invalid offset to get.

You could do this:

${$T}['type']

... I think. I wouldn't really know, because stuff like this is what arrays were kinda made for ;)

$T = array();
for( $i = 1; $i <= 15; $i++) {
    $row = array(
        "type" => $_POST['type_'.$i],
        "hidden" => $_POST['hidden_'.$i],
        "require" => $_POST['require_'.$i]
    );
    if( isset($_POST['question_'.$i.'_list'])) {
        $row['question_'.$i.'_list'] = $_POST['question_'.$i.'_list'];
    }
    $T[] = $row;
}

How's that?

for($i = 1; $i <= 15; $i++){
    $T = 'T'.$i;
    $$T = array(
      'type' => $_POST['type_'.$i], 
      'hidden' => $_POST['hidden_'.$i],
      'require' => $_POST['require_'.$i]);

    if(isset($_POST['question_'.$i.'_list']))
        ${$T}['list'] = $_POST['question_'.$i.'_list'];
}