Convert String To Object-Variable-Name?

class ClassOne {
    public function test() {
        return 'test';
    }
}

class ClassTwo {
    public function test2() {
        return 'test2';
    }
}

$one = new ClassOne();
$two = new ClassTwo();

$objects = array('one', 'two');
$methods = array('test', 'test2');

for ($i = 0; $i < count($objects); $i++) {
    echo ${$objects[$i]}->$methods[$i]();
}

You can store classnames or method names as strings and later use them, or even store variable names, like here ${$objects} (variable variables), but you cannot store whole logic.

To evaluate whole logic, you have to use eval(), which is most probably bad idea

$var = "response->dict->words"
eval("?> <?php echo $".$var.";");

You can split your string and make the call as below:

class Response {
    public $dict;

    public function __construct() {
        $this->dict = new stdClass();
        $this->dict->words = 'words test';
    }
}

$response = new Response();

$var = 'response->dict->words';

$elements = explode('->', $var);

echo ${$elements[0]}->$elements[1]->$elements[2];

Results into words test

Or, if you don't know the level of nesting the object call, you can perform the call in a foreach loop. When the loop exits, the last call will be available after it:

class Response {
    public $dict;

    public function __construct() {
        $this->dict = new stdClass();
        $this->dict->words = new stdClass();
        $this->dict->words->final = 'test chained string';
    }
}

$response = new Response();

$var = 'response->dict->words->final';

$elements = explode('->', $var);

foreach ($elements as $key => $element) {
    if ($key == 0) {
        $call = ${$element};
        continue;
    }
    $call = $call->$element;
}

echo $call;

Results into: test chained string