Generic base class for WinForm UserControl

Question

I created a generic base class for a WinForm UserControl:

public partial class BaseUserControl<T> : UserControl
{
    public virtual void MyMethod<T>() 
    { 
        // some base stuff here 
    }
}

And a UserControl based on that:

public partial class MyControl : BaseUserControl<SomeClass>
{
    public override void MyMethod<SomeClass>() 
    { 
        // some specific stuff here 
        base.MyMethod<SomeClass>();
    }
}

It works fine, but MyControl cannot be edited in the VisualStudio Designer, because it says it cannot load the base class. I tried to define another class BaseUserControl, non generic, hoping it would load it, but the trick doesn't seem to work.

I already have a workaround: define an interface, IMyInterface<T>, and then create my control as

public partial class MyControl : UserControl, IMyInterface<SomeClass>

But I lose my base virtual methods (not a big deal, but still...).

Is there a way to create a base generic class for a UserControl, with the possiblity to edit it in the VisualStudio Designer?

Answer 1

We're doing the same thing and we work around by specializing a class first and derive from the specialized class. Using the code from your example this means something like:

public partial class UserControl : UserControlDesignable 
{

...
}
public class UserControlDesignable : BaseUserControl<Someclass> { }

The designer is still acting flaky sometimes - but most of the time it works.

Answer 2

You'll have to trick the designer by adding a 'regular' class that inherits from your generic base form. Your designable form should then inherit from this class. The following 2 class definitions are thus in the same file. You'll have to make sure that the class that inherits from the generic base user-control, is the last class in the file.

public MyForm : EditableCustomerForm
{}

public EditableCustomerForm : GenericForm<Customer>
{}

The designer will display the first class in the code file that it encounters.