Q129868: How to Pass a UDT to an OLE Automation Server in VB 4.0

Article: Q129868
Product(s): Microsoft Visual Basic for Windows
Version(s): 
Operating System(s): 
Keyword(s): 
Last Modified: 11-JAN-2001

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The information in this article applies to:

- Microsoft Visual Basic Standard Edition, 32-bit, for Windows, version 4.0 
- Microsoft Visual Basic Professional Edition, 16-bit, for Windows, version 4.0 
- Microsoft Visual Basic Professional Edition, 32-bit, for Windows, version 4.0 
- Microsoft Visual Basic Enterprise Edition, 16-bit, for Windows, version 4.0 
- Microsoft Visual Basic Enterprise Edition, 32-bit, for Windows, version 4.0 
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SUMMARY
=======

This article shows by example how to pass a user-defined type (UDT) to an OLE
Automation server in Visual Basic version 4.0.

MORE INFORMATION
================

A UDT cannot be passed to a public member function of an OLE Automation Server.
This behavior is by design. However, it is possible to pass a UDT to a private
member function or to declare a private variable of a user defined type within a
class module. But because these are private, they cannot be accessed directly by
an OLE Automation Controller or Client. Therefore, you need to pass each field
of the UDT, element by element, or create a class with public variables
corresponding to each field of the UDT.

Step-by-Step Example
--------------------

There are two parts to this example - creating the OLE Automation Server and
creating the OLE Automation Controller.

Part One: Create the OLE Automation Server
------------------------------------------

1. Start a new project in Visual Basic. Form1 is created by default.

2. Choose Class Module from the Insert menu. Class1 is created by default.

3. Add the following code to the General Declarations section of Class1:

     Private Type UDT
        age As Integer
        name As String
     End Type

     Private ClassUDT As UDT

     Public Sub GetUDTFields(age As Integer, name As String)
        ClassUDT.age = age
        ClassUDT.name = name
     End Sub

     Public Sub DispalyClassUDT()
     MsgBox "Hi! My Name is " & ClassUDT.name & ". I am " & _
        ClassUDT.age & " years old"
     End Sub

4. Set the following properties for Class1:

  Properties     Value
  -------------------------------------
  Instancing     2 - Creatable MultiUse
  Name           Class1
  Public         True

5. Choose Module from the Insert menu. Module1 is created by default.

6. Add the following code to the General Declarations section of Module1:

     Sub main()

     End Sub

7. Choose Options from the Tools menu, and in the Project Options, select Sub
  Main as the Startup Form and OLE Server as the StartMode.

8. The OLE Automation server is now ready. Press the F5 key to run the program,
  and then minimize it.

Part Two: Create the OLE Automation Controller
----------------------------------------------

1. Start a new instance of Visual Basic.

2. Start a new project in Visual Basic. Form1 is created by default.

3. Add the following code to the General Declarations section of Form1:

     Private Type UDT
        age As Integer
        name As String
     End Type

4. Add the following code to the Form_Click event of Form1:

     Dim x As Object
     Dim MyUDT As UDT

     MyUDT.age = 25
     MyUDT.name = "Joe"
     Set x = CreateObject("Project1.Class1")
     x.GetUDTFields MyUDT.age, MyUDT.name
     x.DispalyClassUDT

5. Press the F5 key to run the program. Click Form1. A message box will display
  the fields of the UDT passed element-by-element to the OLE Automation server.

Additional query words: 4.00 vb4win vb4all

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Keywords          :  
Technology        : kbVBSearch kbAudDeveloper kbVB400Search kbVB400 kbVB16bitSearch

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