reuse select menu with different ids' and names' in twig - twig

Question

I would like to reuse a select menu, but change every time the id and the name for it in Twig. How could it be done?
I thought of a wrapper block about the select menu and then extend it each time of reuse. But how to set the values for id and name using {{ parent() }}?

Answer 1

I do this by storing and creating the keys in my custom Twig_Extension class, here is a small setup for it. By keeping it global I can ensure unique id's in every view/macro/include ...
example.twig
{% for i in 1..5 %}
<ul id="{{ get_unique_key('my_menu') }}">
<li>Foo</li>
</ul>
{% endfor %}
ProjectTwigExtension
class ProjectTwigExtension extends Twig_Extension {
private $keys = array();
public function getFunctions() {
return array(
new Twig_SimpleFunction('get_unique_key', array($this, 'getUniqueKey')),
);
}
/**
* Create an unique HTML identifier
*
* #param $name String to make unique
*
* #returns String
*/
public function getUniqueKey($name) {
if (!in_array($name, $this->keys)) {
$this->keys[] = $name;
return $name;
}
$i = 0;
while(in_array($name.++$i,$this->keys)) {}
$this->keys[] = $name.$i;
return $name.$i;
}
public function getName() {
return 'ProjectTwigExtension';
}
}
Register extension
$twig = new Twig_Environment($loader);
$twig->addExtension(new ProjectTwigExtension());