Hello,
  I am building a VB.NET form interface for a legacy Visual FoxPro
7.0 (VFP) DLL (which contains our business logic).  Basically, the
form instantiates multiple instances of the VFP object (via COM
interop) in separate threads.  I would like each VFP object to be
completely independent of the others.

  In the VFP DLL, we have VFP variables that are declared using the
"public" keyword.  As best as I can tell, VFP "public" variables have
the same scope as a variable declared as "shared friend" in VB.NET.

  MY PROBLEM is that, under our old VFP model these DLLS used to run
in several separate processes, so "public" variables were not in the
same memory space and would not conflict with each other.  But, now
that we have several instances running under different threads in the
same process, they are all interpreted as being the same instance.
This produces locking and overwrite errors.

  Is there any way of getting each instance declared in a separate
thread to avoid this conflict (maybe forcing a variable to be declared
in a completely new memory space, or something)?

  The only solution we have come up with so far is to recompile the
VFP DLL for as many threads as we could need, each with a different
name (VFPLegacyLogic1.DLL, VFPLegacyLogic2.DLL, VFPLegacyLogic3.DLL,
etc...), so that each variables is considered part of a different
assembly.  But, obviously this is hokey, inefficient, and limits the #
of threads we can run.

  I have attached a simplified example of our problem below
(StartExample, Method1, and Method2 are the functions of use in the
VB.NET code)...  you can see that setting the VFP "public" value in
one thread affects the instances value in the other thread.

  I cannot change the way our VFP "public" variable is accessed (ie.
THIS.gcString), but I can change the way it is declared (ie. some way
of declaring it with the .NET equivalent of "friend", but not
"shared".)

----VB.NET code----
Imports System.Threading
Public Class Form1
   Inherits System.Windows.Forms.Form

   Private components As System.ComponentModel.IContainer
   Friend WithEvents btnThread1 As System.Windows.Forms.Button

   Private Sub StartExample(ByVal sender As System.Object _
                , ByVal e As System.EventArgs) _
                  Handles btnThread1.Click
       Dim loThread1 As New Thread(AddressOf Method1)
       Dim loThread2 As New Thread(AddressOf Method2)

       loThread1.ApartmentState = ApartmentState.STA

       'start the first thread
       loThread1.Start()

       'loop until the first thread is suspended
       ' and has set the value to 1
       Do While Not loThread1.ThreadState = ThreadState.Suspended
       Loop

       loThread2.ApartmentState = ApartmentState.STA

       'start the second thread
       loThread2.Start()

       'loop until the second thread is suspended
       ' and has set the value to 2
       Do While Not loThread2.ThreadState = ThreadState.Suspended
       Loop

       'allow the first thread to finish
       loThread1.Resume()
       loThread1.Join()

       'allow the second thread to finish (does nothing)
       loThread2.Resume()
       loThread2.Join()
   End Sub

   Private Sub Method1()
       Dim loVFPTest1 As New vfpthreadtest.publicthreadvarClass

       'set the value
       loVFPTest1.SetValue("1")

       'suspend the thread
       ' will resume after Method2 sets the value to 2)
       Thread.CurrentThread.Suspend()

       'get the value (shows 2, because variable is VFP
       ' "public" and was set to 2 in the Method2)
       MsgBox("Thread1: " & loVFPTest1.GetValue())
   End Sub

   Private Sub Method2()
       Dim loVFPTest2 As New vfpthreadtest.publicthreadvarClass

       'get the value (shows 1, because variable is
       ' VFP "public" and was set to 1 in Method1)
       MsgBox("Thread2: " & loVFPTest2.GetValue())

       'set the value
       loVFPTest2.SetValue("2")

       'suspend the thread
       Thread.CurrentThread.Suspend()
   End Sub

   Public Sub New()
       MyBase.New()
       Me.btnThread1 = New System.Windows.Forms.Button
       Me.SuspendLayout()
       Me.btnThread1.Location = New System.Drawing.Point(8, 8)
       Me.btnThread1.Name = "btnThread1"
       Me.btnThread1.Size = New System.Drawing.Size(120, 32)
       Me.btnThread1.TabIndex = 0
       Me.btnThread1.Text = "Start"
       Me.AutoScaleBaseSize = New System.Drawing.Size(5, 13)
       Me.ClientSize = New System.Drawing.Size(408, 272)
       Me.Controls.Add(Me.btnThread1)
       Me.Name = "Form1"
       Me.Text = "Form1"
       Me.ResumeLayout(False)
   End Sub

   Protected Overloads Overrides _
    Sub Dispose(ByVal disposing As Boolean)
       If disposing Then
           If Not (components Is Nothing) Then
               components.Dispose()
           End If
       End If
       MyBase.Dispose(disposing)
   End Sub
End Class
----END VB.NET code----

----VFP code (compiled using a VFP Project called "vfpthreadtest"----
DEFINE CLASS PublicThreadVarClass AS Custom

PROCEDURE Init
PUBLIC gcString

ENDPROC

PROCEDURE setvalue
LPARAMETERS tcValue

gcString = tcValue

ENDPROC

PROCEDURE getvalue
RETURN gcString

ENDPROC
ENDDEFINE
----END VFP code----

           Thanks in advance for any help that can be provided,
                     -Brian