use Webmozart\Assert\Assert;

class Employee
{
    public function __construct($id)
    {
        Assert::integer($id, 'The employee ID must be an integer. Got: %s');
        Assert::greaterThan($id, 0, 'The employee ID must be a positive integer. Got: %s');
    }
}
new Employee('foobar');
// => InvalidArgumentException: 
//    The employee ID must be an integer. Got: string

new Employee(-10);
// => InvalidArgumentException: 
//    The employee ID must be a positive integer. Got: -10