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I have the code you see below. As such VS defines my two lists in FormMain.cs.design like this: DRT_Tvw_TableList drt_Tvw_TableList; and DRT_Tvw_TableList_Filtered drt_Tvw_TableList_Filtered;

To allow me to leverage inheritence in my code, I want to instead define them like this: DRT_Tvw_Abstract drt_Tvw_TableList; and DRT_Tvw_Abstract drt_Tvw_TableList_Filtered;

So far, all I've been able to do is manually edit the FormMain.cs.design. Is there a way to force VS to use DRT_Tvw_Abstract to define my two treeviews in FormMain.cs.design, e.g., make the abstract class appear in the toolbox so I can drop it onto my form? 

public abstract class DRT_Tvw_Abstract : TreeView
{
    public DRT_Tvw_Abstract() : base()
    {
    }
}

public class DRT_Tvw_TableList_Unfiltered : DRT_Tvw_Abstract
{

    public DRT_Tvw_TableList_Unfiltered() : base()
    {

    }
}

public class DRT_Tvw_TableList_Filtered : DRT_Tvw_Abstract
{
    public DRT_Tvw_TableList_Filtered() : base()
    {
    }
}

Update

in practice, I'm using it like this (i.e., manually editing FormMain.Designer.cs to make its code look like the following)

DRT_Tvw_Abstract drt_Tvw_TableList_Unfiltered;
DRT_Tvw_Abstract drt_Tvw_TableList_Filtered;

drt_Tvw_TableList_Unfiltered = new DRT.DRT_Tvw_TableList_Unfiltered();
drt_Tvw_TableList_Filtered = new DRT.DRT_Tvw_TableList_Filtered();

The reason I'm doing this is because there is a boatload of code that the two tree views share. Most of the code is identical for both and as such it is implemented in the abstract class. One difference between the two treeviews is that the treeviews are loaded differently:

  1. drt_Tvw_TableList_Unfiltered is loaded from a datatable. As such, it has a CreateTreeView(DataTable dataTable) method

    drt_Tvw_TableList_Filtered is loaded from drt_Tvw_TableList_Unfiltered. As such, it has a CreateTreeView(DRT_Tvw_TableList_Unfiltered drt_Tvw_TableList_Unfiltered) method

I could implement both these in the abstract (same method name, different arguments), but I chose to implement each in the concrete class to which each belongs.

There are other differences. I deal with them either by writing custom methods in the two concrete classes or overriding abstract class abstract methods in the concrete classes

I want to make VS use the abstract class when it creates its code in FormMain.Designer.cs so I don't have to worry about VS changing them back to the concrete class names and thereby forcing me to manually edit FormMain.Designer.cs again and again

VA systems engineer
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  • How would it know what to `new` up then in the `InitializeComponent()`? You can't create an instance of an `abstract`. Maybe remove the abstract? Even `Control` isn't abstract. – TyCobb Jun 15 '18 at 17:01
  • This still has a code smell though that I don't think you need. Can you elaborate what you really want to do? Why would you need to define the controls themselves as the base? – TyCobb Jun 15 '18 at 17:08
  • @tycobb: see **Update** – VA systems engineer Jun 15 '18 at 17:39
  • Still lost, you can declare it as `MyDerivedControl` and still work with them as `MyAbstractControl`. I don't follow why you need to declare them as the base type. You should NEVER edit the designer.cs. You touch that form at all and you just lost any code you had written. – TyCobb Jun 15 '18 at 17:54
  • @tycobb: I agree - The need to edit Designer code is the entire basis for my question. Unless I'm missing something (and I don't think I am - my code works fine) the only way to leverage inheritance (i.e., have all the code inside the abstract work for any of its derived classes) is to define each derived class using the abstract data type. This is how the code in the abstract class figures out which derived class its currently working with. Am I missing something? Again, the only "problem" I have is that VS insists on defining my two derived treeview classes using their concrete class names – VA systems engineer Jun 15 '18 at 18:02
  • @tycobb: I didn't see this before, but check out [How can I get Visual Studio 2008 Windows Forms designer to render a Form that implements an abstract base class?](https://stackoverflow.com/questions/1620847/how-can-i-get-visual-studio-2008-windows-forms-designer-to-render-a-form-that-im) from 2008. Same/similar problem – VA systems engineer Jun 15 '18 at 18:08

0 Answers0