INFO: Form Events and Sub Procedures Can Be Exposed (143311)

MORE INFORMATION

In Visual Basic 3.0, a form's events and sub procedures were private to the form, and could not be accessed outside of the form's scope. Because a form is public in Visual Basic 4.0 and higher, its events and sub procedures can be exposed by either prefacing it with Public or by removing Private from the event.

Step-by-Step Example

The following example works in Visual Basic 4.0 and higher but not in Visual Basic 3.0. To create the program, do the following:

1. Start Visual Basic or from the File menu, choose New Project (ALT, F, N) if Visual Basic is already running. Form1 is created by default.
2. In Form1 enter the following code:

         Sub DispMsg ()
             MsgBox "Inside Sub"
         End Sub
   						

3. Add a module to the project and in Module1 enter the following code:

         Sub main()
            'some other code stuff could go here
            Call Form1.DispMsg
         End Sub
   						

4. For VB4, select the Tools, Options menu item and the Project tab. Set Startup Form to Sub Main.
5. For VB5/6: Select the Project, Properties menu item and the General tab. Set the Startup Object to Sub Main.
6. Run this program. The Module1 Main sub procedure calls the DispMsg sub procedure in the form.
   
   NOTE: Invoking an event through code is not good programming practice. However, you can get at routines and form events if needed. Just ensure that they are visible members of the class (the form in this case).