In Excel VSTO Document-Level Customizations, how do I pass “Globals.Sheetn” to parameters expecing an Excel.Worksheet interface?

Question

When I'm writing code in the partial class file for a worksheet (Sheet8, for instance), how do I pass "this" class as an argument expecting objects with the Microsoft.Office.Interop.Excel.Worksheet interface?

Here's an example of from the Sheet8.cs file:

public partial class Sheet8
{
    private void Sheet8_startup(object sender, System.EventArgs e)
    {
        var object = new MyCustomClass(this);
    }
}

And the consuming code that I'd like to write:

class MyCustomClass
{
    public MyCustomClass(Microsoft.Office.Interop.Excel.Worksheet sheet)
    {
        // Do something with the sheet
    }
}

The problem seems to be that "this" always refers to the Sheet n object, and cannot be cast to the interface type necessary for creating loosely-coupled interfaces with custom code. Any suggestions?

Answer 1

After weeks of searching, I figured it out. It's actually embarrassingly simple.

Each Globals.SheetN object has an InnerObject() method that returns an object with the right interface. An example of how to use it:

public partial class Sheet8
{
    Sheet8_startup(object sender, System.EventArgs e)
    {
        var sheet = new MyCustomClass(InnerObject());
    }
}

From there, you can build loosely-coupled, custom objects to your heart's content!

Answer 2

You can also use the this keyword instead of InnerObject() .

public partial class Sheet8
{
        Sheet8_startup(object sender, System.EventArgs e)
    {
        var sheet = new MyCustomClass(this);
    }
}

Then, for the constructor of your consuming class use the Microsoft.Office.Tools.Excel.WorksheetBase type (instead of the Worksheet type).

class MyCustomClass
{
    public MyCustomClass(Microsoft.Office.Interop.Excel.WorksheetBase sheet)
    {
        // Do something with the sheet
    }
}