PHP Treat String as Variable

I have a piece of code here that does not work despite me using a $$ on it to treat the string as a variable:

<? foreach (KOHANA::config('list.amenities_forms') as $k => $v) : ?>
        <div class="form">
            <fieldset>
                <legend><?php echo $v ?></legend>
                <input type="checkbox" name="<?=$k?>flag" id="<?=$k?>flag"/>
                <label class="inline"><?=$v?></label>

                <label>Description</label>
                <textarea cols="50" rows="5" name="<?=$k?>[]"><?= empty($$k[0]) ? '' : $$k[0]?></textarea>

                <label>Size</label>
                <input type="text" name="<?=$k?>[]" value="<?= empty($$k[1]) ? '' : $$k[1]?>"/>

                <label>Capacity</label>
                <input type="text" name="<?=$k?>[]" value="<?= empty($$k[2]) ? '' : $$k[2]?>"/>
            </fieldset>
        </div>
    <? endforeach?>

the function Kohana::config returns this array:

'amenities_forms' => array(
        'meeting_space' => 'Meeting Space',
        'breakfast_room' =>开发者_如何学Python; 'Breakfast Room',
        'living_quarters' => 'Living Quarters',
        'restaurant' => 'Restaurant',
        'bar' => 'Bar'
    )

what could I be doing wrong?

---

I think the problem is the fact that PHP interprets $$k[0] as using the string from the variable $k[0] as the name of the variable, when you wanted to only use the contents of the $k variable as name of the variable. Using ${$k}[0] instead, should make PHP understand what you wanted do and not use the array index as part of the $k variable.

For example,

<?php
$foo[0] = 'bar';
$k = 'foo';
echo ${$k}[0];
?>

This will output "bar", but it would not work without the curly braces.