private methods in interface?

[Malfunction]

I have a set of customized controls. E.g. they extend "RadioButton", "TextBox" and "CheckBox". Now I have added a couple of methods that these controls have in common (same implementation, too). Since they (my customized controls) can only inherit one type I wanted to put these common methods into an interface.

 

That way I would still have to copy the methods' body into every control but that would at least guarantee that these controls implement the common methods.

 

Now the problem:

Some of the common methods are private or protected or even have the override modifier but my interface tells me it wont let me use these :(

 

Should I just delete the interface and copy the methods to each control - not letting anyone know that they have these methods in common?

 

Or is there a chance for my interface to survive?

 

edit: "Explicit interface member implementation" doesn't help either...

Edited March 12, 2004 by Malfunction

[PlausiblyDamp]

Interfaces by definition contain public functionality, they are designed to provide a consistant public interface to a series of components. Basically you can't put protected or private members into and interface.

However if your controls are in a single classlibrary you could mark the interface as being internal (friend in vb) and in each of the classes mark their implementation as also being internal. This way the interface can be used within the DLL but not from outside the DLL.

[Nerseus]

I'd second Plausably's solution. If you just used the same named method names in each class, but not through an interface, then you lose the ability to cast an instnace of your control to the interface and call one of your new methods. Obviously that's only a benefit if you need that functionality, but I would think you would want it at some point.

 

-ner

[Heiko]

You need not copy the functionality.

 

You can programm a common HelperClass that is called by all classes.

 

Public Class A implements IX

Private _IXHelper as new IXHelper

Private Sub Soso (ByVal jaja as string)
 _UXHelper.Soso(jaja)
End sub

Public Sub Dada (ByVal nene as string) implements IX.Dada
  nene = someLocalPreprocessing (nene)
 _UXHelper.Dada(nene)
End sub

End Class

Public Class B implements IX

Private _IXHelper as new IXHelper

Private Sub Soso (ByVal jaja as string)
 _UXHelper.Soso(jaja)
End sub

Public Sub Dada (ByVal nene as string) implements IX.Dada
  nene = someOtherStuff (nene)
 _UXHelper.Dada(nene)
End sub

End Class

[DR00ME]

Just because an interface is public doesn't mean you have to implement it publicly. Implementing the interface privately is actually better. If you make every method implemented in private, you can no longer access specific methods directly. You have to use a reference to the interface. :p

[dynamic_sysop]

you can access Private members still if you implement as Private in many cases by specifying the BindingFlags in a way like this ...

Reflection.BindingFlags.NonPublic [color=Blue]Or[/color] Reflection.BindingFlags.Instance

[DR00ME]

I knew it! at least I tried! :D Edited March 12, 2004 by DR00ME

[Malfunction]

I thought about implementing a helper class but what about event-handlers?

My controls have a couple of identical event-handlers...

[Heiko]

Uh.

I didn't have to tackle that problem.

 

Can you add the event handlers by code ?

 

 

Public Class malFunctionsTextBox
Inherits TextBox

Private _mF as new mFHelper

Private Sub New()
 Mybase.New
 AddHandler me.OnClick, AddressOf _mF.Click
End Sub

End Class