Questions on Usage of a .NET Component from VB6 and VBScript

[Igor Ladnik]

We are dealing with .NET server component and COM clients written with VB6 and VBScript. And there are some problems we faced (please see code below).

1. Managed type System Drawing.Color is automatically marshaled to VB type OLE_COLOR only in case of early binding. (see DealWithColor() method).

2. For class Component public variable DateTime dt can be used in both early and late binding cases, whereas public variable Color clr causes failure in late binding and works fine in early binding.

3. Method public void Info(MyPointClass pt) works fine with VB6 for both early and late binding but fails in VBScript.

    [ComVisible(true)]
    public struct MYPOINT
    {
        // These are now private!
        private int xPos;
        private int yPos;
 
        [MarshalAs(UnmanagedType.BStr)]
        private string name;
 
        // Add some members to the MYPOINT struct.
        public void SetPoint(int x, int y) { xPos = x; yPos = y; }
        public void DisplayPoint() { MessageBox.Show(string.Format("X: {0} Y: {1}", xPos, yPos), name); }
    }
 
    [ComVisible(true)]
    [ClassInterface(ClassInterfaceType.AutoDual)]
    public class MyPointClass
    {
        private int xPos;
        private int yPos;
        private string name;
 
        public void SetPoint(string name, int x, int y) { this.name = name; xPos = x; yPos = y; }
        public void DisplayPoint() { MessageBox.Show(string.Format("X: {0} Y: {1}", xPos, yPos), name); }
    }
 
[ComVisible(true)]
[ClassInterface(ClassInterfaceType.AutoDual)]
public class Component
{
      // Success in Early Binding. Failure in Late Binding (Both VB6 and VBScript)
    public Color clr;
 
      // Success in Early Binding and Late Binding (Both VB6 and VBScript)
      public DateTime dt;
 
    // Success in Early Binding. Failure in Late Binding (Both VB6 and VBScript)
public Color DealWithColor(Color col)
      {
          MessageBox.Show(col.ToString(), "DealWithColor() Method");
          return col;
      }
 
// Success in Early Binding. TODO Late
public void Info(ref MYPOINT pt)
      {
          pt.DisplayPoint();
      }
 
      // Success in Early Binding and Late Binding (Both VB6 and VBScript)
      public void Info (object pt)
      {
          (pt as MyPointClass).DisplayPoint();
      }
 
// Success in Early Binding and in Late Binding VB6. Failure in VBScript.
      public void Info (MyPointClass pt)
      {
          pt.DisplayPoint();
      }
}
 
 

    'Late Binding via VB6
   '''''''''''''''''''''''''''''''''''
    Dim ptc As CallNetFromVB6.MyPointClass
    Dim col1 As OLE_COLOR
    Dim objLate As Object
    Set objLate = CreateObject("CallNetFromVB6.Component")
 
    objLate.dt = Now                 'Success
 
    Set ptc = New CallNetFromVB6.MyPointClass
    ptc.SetPoint "From Class", 11, 22
    objLate.Info_2 ptc                      'Success
 
    objLate.clr = vbRed                 'Fail 
    col1 = objLate.DealWithColor(col)     'Fail 
 
 
    'Late Binding via VBScript
    ''''''''''''''''''''''''''''''''''
    Set objLate = CreateObject("CallNetFromVB6.Component")
    Set ptLate = CreateObject("CallNetFromVB6.MyPointClass")
 
    objLate.dt = Now                 'Success
 
    Set ptc = New CallNetFromVB6.MyPointClass
    ptc.SetPoint "From Class", 11, 22
    objLate.Info_2 ptc                       'Fail
 
    objLate.clr = vbRed                 'Fail 
    col1 = objLate.DealWithColor(col)     'Fail 
 
 

Thanks.

Igor Ladnik
Barak Cohen

[Frinavale]

Now that you've determined how .NET's Interop is not properly Marshaling your VB6 and VBScript components, consider Marshaling your VB6 and VBScript components yourself:

Write a wrapper class around the VB and VBScript components that will handle the Marshaling instead of leaving this up to .NET to do.

-Frinny