Question

I’m aware of these two questions which explain why I can’t have a protected/private method in an interface, what I’m trying to work out is how to control from where my methods are called, briefly:

public class EditField : IEditField {     public EditField() {}     public EditField(IStateMachine stateMachine) {}     public void Action_Commit() {}     public void Action_Undo() {} } 

Consumers can use the default IStateMachine, or roll their own.

I was wondering if there is any way to ensure that Action_ methods are only called from within an IStateMachine, so that consumers don’t start messing around with state stuff. I suspect there’s no way of doing this, but wondered if I’m missing something. I’m not a Design Pattern guru.

Answer 1

While you can’t have access modifiers on interfaces, but here’s one way to hide the members, yet make them accessible to IStateMachine implementors.

public interface IEditActions {   void Action_Commit() {}   void Action_Undo() {} }  public interface IStateMachine {   void Initialize(IEditActions editActions); }  public class EditField : IEditField {   private class EditActions : IEditActions   {     EditField _editField;      public EditActions(EditField editField)     {       _editField = editField;     }      public void Action_Commit()     {       _editField.Action_Commit();     }     public void Action_Undo()     {       _editField.Action_Undo();     }   }    public EditField() {}   public EditField(IStateMachine stateMachine)   {     stateMachine.Initialize(new EditActions(this));   }    private void Action_Commit() {}   private void Action_Undo() {} }