Question

I have a base windows forms class which contains two buttons: Ok and Cancel. This base form implements the interface IBaseForm:

public interface IBaseForm
{
  string FormText {get;set;}
  DialogResult ShowView(IWin32Window owner);
}

public partial class BaseForm : IBaseForm
{
  ...
}

Next I have a window class which inherits from BaseForm and implements another interface IItem:

public interface IItem : IBaseForm // here is problem
{
  string ItemName {get; set;}
  ...
}

public partial class AddItemForm : BaseForm, IItem
{
  ...
  // I don't have to implement IItem here, because it is implement in BaseForm
}

The problem is with the inheritance of IBaseForm; I have to inherit it two times.
In code I have:

IItem view = new AddItemForm();
view.FormText = "Add new item";

If I remove inheritance from IItem, view.FormText will be not visible. If I remove the inheritance from BaseForm I have to implement IBaseForm in each AddItemForm. I’ve only showed one itemForm but it is a lot, and I have to implement this many times.

How I can resolve this problem?

Answer 1

There isn’t another way to do this. BaseForm is a class, whereas IItem is an unrelated interface. Neither is a ‘super’ or ‘base’ of the other, so you need to inherit from IBaseForm in both of them.