function importValue($value)
{
if (!in_array($value, $this->getAvailableValues())) {
$value = null;
$this->setError(FormControlError::invalid());
}
if (!$value && !$this->isOptional()) {
$this->setError(FormControlError::missing());
}
return parent::importValue($value);
}
function __construct($name, $label)
{
Assert::isTrue(preg_match(FormControlSet::NAME_PATTERN, $name), 'name of a set should contain alphanumeric symbols, glyphs and underscored only');
parent::__construct($name, $label);
}