from flightphp framework documention:
By default, every time you load your class you will get a shared instance. To get a new instance of a class, simply pass in false as a parameter:
// Shared instance of the class
$shared = Flight::db();
// New instance of the class
$new = Flight::db(false);
what is shared instance? what is difference between these two type in action?
Flight::db() is a static method that returns an instance of the class.
Normally a singleton pattern is used, which means, if call Flight::db() several times, all variables point to the same instance.
if you call Flight::db(false), a new object is created for every call, which means if you call it several times, you get an own object for every call.