SFML Game Development - Chapter - 4

[Mortal]

first i want thanks everybody who contributed in the book, however, i'm reading chapter 4, i found  in std::fonctional expression in Command class

std::function<void(SceneNode&, sf::Time)>       action;

and functor in AircraftMover class

void operator() (Aircraft& aircraft, sf::Time) const
{
        aircraft.accelerate(velocity);
}

take two arguments. the second argument is sf::Time type which is never computed throughout all classes. My question why is it there while it never be considered?

[eXpl0it3r]

Are you looking at the official code on GitHub or just the one downloaded from Packt/in the book?

I unfortunately couldn't figure out where the posted code is from exactly.

[Mortal]

hello @eXpl0it3r
it is from github. i could not know why sf::Time argument there really it confuses me. i hope it is there just for later used in proceeding chapters. i haven't finished the book yet