[devit]

You can use a macro instead of copy and pasting.

You can also do this:

  struct Vehicle
  {
    speed: f32,
    type: VehicleType
  }

  enum VehicleType
  {
    Car(...),
    Bicycle(...)
  }

Or this (although this is the least common):

  struct Vehicle
  {
    data: VehicleData
    type: Box<dyn SpecificVehicle>
  }

  struct VehicleData
  {
    speed: f32,
  }

  trait SpecificVehicle
  {
    fn quack(&self, data: &VehicleData);
  }

  impl SpecificVehicle for Car {...}
  impl SpecificVehicle for Bicycle {...}