PRB: Empty Sub Procedures Are Not Persistent

MORE INFORMATION

The Visual Basic Help file lists the following possible reasons for the "Sub or Function not defined" error:

• The specified procedure is not visible to the calling procedure. Procedures in a form cannot be called from procedures outside the form. Use Find on the Edit menu to locate the procedure.
• You have declared a dynamic-link library, but the routine is not in the specified library.
• You have misspelled the name of your procedure.

An additional possible cause for this error is that you have called an empty event procedure. Empty Sub procedures are not persistent in Visual Basic, that is, the compiler strips out empty event procedures before the binding tables are built such that a reference does not exist to the procedure in the compiled code, and as a result, it is undefined.

Steps to Reproduce Behavior

1. Start a new project in Visual Basic. Form1 is created by default.
2. Add the following code to the Form1_Click event procedure:

      Private Form1_Click()
         Command1_Click
      End Sub
   						

3. Add a command button (Command1) to Form1.
4. Run the program. When you click the form, the error is generated.
5. Furthermore, if you nondestructively edit the line "Command1_Click" (that is, retype a portion of the line) the error "Sub or Function not defined" is generated at compile time.