Bus Ride, code snippet 24

busride_code_snippet_24.go

// Board adds the given Passenger to the Bus and charges them a ticket price calculated by chargeFn if they don't already have a paid ticket.
// Board returns false if the Passenger was not allowed to board the Bus.
func (b *Bus) Board(p *Passenger, chargeFn PriceCalculator) bool {
	var allowed bool // Default value is false
	if p.HasValidTicket {
		allowed = true
	} else {
		amount := chargeFn(*p)
		passenger := p.Charge(amount)
		allowed = passenger.HasValidTicket
	}
	if allowed {
		b.add(p)
	}
	return allowed
}

// Charge prints a message that the Passenger has been charged "amount" money, and returns a copy with validTicket = true.
func (p Passenger) Charge(amount float64) Passenger {
	if p.HasValidTicket {
		return p // We already charged this Passenger.
	}
	fmt.Printf("Passenger with SSN %s: charged %.2f of arbitrary money\n", p.SSN, amount)
	p.HasValidTicket = true
	return p
}

// PriceCalculator is the type used by BusCompany to determine the ticket price for a Passenger.
// PriceCalculator returns the ticket price in the local currency.
type PriceCalculator func(p Passenger) float64