C# - abstract method parameter, specifically set for classes implementing it

Question

I want to implement a class which stores different appearances for different controls. At first I thought to use generics, as such:

public class Appearance<T where T : Control> { ... }

but there are two problems. First of all, I want to use these appearances in a list for different controls, namely different T (impossible in this case). Secondly each control type's appearance will have different properties according to the control it is refering. So the solution is a base class (preferably abstract) and derived classes for each control type:

abstract class Appearance { ... }
public class TextBoxAppearance : Appearance { ... }
public class ComboBoxAppearance : Appearance { ... }

My problem now is that I would like to achieve encapsulation regarding the control types, each class concerns, namely:

public abstract class Appearance {
    public abstract void updateAppearanceOf(Control control);
}
public class TextBoxAppearance : Appearance {
    public void updateAppearanceOf([here I want to give TextBox instead of Control])
    {
        // implement update of TextBox
    }
}
public class ComboBoxAppearance : Appearance {
    public void updateAppearanceOf([here I want to give ComboBox instead of Control])
    {
        // implement update of ComboBox
    }
}

Is this possible?

Answer 1

You can make your base class explicitly implement IAppearance

public interface IAppearance
{
    void updateAppearanceOf(Control control);
}
public abstract class Appearance<T> : IAppearance where T : Control 
{
    void IAppearance.updateAppearanceOf(Control control)
    {
        if (control is T) updateAppearanceOf((T)control);
    }
    public abstract void updateAppearanceOf(T control);
}
public class TextBoxAppearance : Appearance<TextBox> {
    public override void updateAppearanceOf(TextBox control)
    {
        // implement update of TextBox
    }
}

This way all the classes implementing the abstract Appearance just have to worry about how to handle their control.