How to create WinForms components based on the type of an object

Question

Lets say we have this interface:

interface IVehicle { ... }

And some classes implementing it:

class Car : IVehicle { ... }
class Boat : IVehicle { ... }
class Plane : IVehicle { ... }

In my user interface I have a FlowLayoutPanel and access to some sort of an IEnumerable<IVehicle> with a number of various IVehicle objects.

Now I want to create a UserControl for each of the vehicles and add it to the FlowLayoutPanel. The controls will be kind of similar, but since there are vehicles of different types some of the controls might need to look slightly different or work in a different way so that the user can easily work with his vehicles. How can I best solve this without too much clutter?

Answer 1

How about using some sort of factory method:

UserControl CreateControl(IVehicle vehicle) 
{
    if (vehicle is Car)
    {
        return new CarControl();
    }
    else if (vehicle is Boat)
    {
        return new BoatControl();
    }
    ...
}

Answer 2

I am not sure what exactly you are aiming for, but you can use generics when you extend user controls in the usual way:

public class VehicleControl<TVehicle>: UserControl
where TVehicle:IVehicle
{
  //do something specific with IVehicle 
}

public class CarControl : VehicleControl<Car>
{
  //add stuff specific for the Car
}

Answer 3

If you know when writing the code how the mapping looks like, you can set up at Dictionary with mappings:

private Dictionary<Type, Type> _vehicleToControlTypeMappings = new Dictionary<Type, Type>();

Load mappings at startup:

_vehicleToControlTypeMappings.Add(typeof(Car), typeof(CarControl));
_vehicleToControlTypeMappings.Add(typeof(Plane), typeof(PlaneControl));

...and provide a method for getting a new control based on a vehicle:

private Control GetVehicleControl(IVehicle vehicle)
{
    Control result = (Control)Activator.CreateInstance(
        _vehicleToControlTypeMappings[(vehicle as object).GetType()]
        );
    // perform additional initialization of the control
    return result;
}

Then you can simply pass objects of types that implements IVehicle into the method:

IVehicle vehicle = new Car();
Control newctl = GetVehicleControl(vehicle);

Answer 4

In your interface IVehicle, you could add a method to get the user control.

public interface IVehicle
{
    UserControl GetVehicleControl();
}

If you need a control for each vehicle, you can use this code:

public class Car : IVehicle
{
    public UserControl GetVehicleControl()
    {
         return new CarControl();
    }
}

Else if you need only one control for each vehicle type:

public class Car : IVehicle
{
    private static CarControl m_control;

    public UserControl GetVehicleControl()
    {
         if(m_control == null)
             m_control = new CarControl();

         return m_control;
    }
}