FIX: VFP 3 Form or Class Modified in VFP 5 Loses Method Code

• Microsoft Visual FoxPro for Windows, version 5.0

SYMPTOMS

Modifying a form created in Visual FoxPro 3.0 or 3.0b may, under certain circumstances, result in temporary or permanent loss of event or method procedure code.

-or-

Instantiating a class created in Visual FoxPro 3.0 or 3.0b may, under certain circumstances, result in temporary or permanent loss of event or method procedure code.

This can happen if both of the following conditions are true:

• Code is contained in method or event procedures within dependent controls, such as the following:

        - Option buttons in option groups
        - Command buttons in CommandGroups
        - Grid columns in grids or headers within columns
        - Pages in PageFrames
  

• The Visual FoxPro 3.0x form is modified under Visual FoxPro 5.0 without being first run or compiled under Visual FoxPro 5.0, or the Visual FoxPro 3.0x class is instantiated under Visual FoxPro 5.0 without being first compiled under Visual FoxPro 5.0.

• If code is not contained in dependent controls.
• If the Visual FoxPro 3.x form or class is run or instantiated prior to modification in Visual FoxPro 5.
• The form or class is compiled with COMPILE FORM or COMPILE CLASSLIB before form modification or class instantiation.

RESOLUTION

Issuing a COMPILE FORM or COMPILE CLASSLIB command against the form or class library sometimes, but not always, repairs the file in question. If any other changes are made to the form or class and the form or class is saved, compiling is not likely to retrieve the lost code.

STATUS

Microsoft has confirmed this to be a problem in the Microsoft products listed at the beginning of this article. This problem has been fixed in Visual FoxPro 5.0a.

MORE INFORMATION

The format of compiled object code has been changed between Visual FoxPro 3.0x and Visual FoxPro 5.0. Any event or method procedure code is automatically recompiled when a Visual FoxPro 3.0x form is modified or run in Visual FoxPro 5.0. Classes created in Visual FoxPro 3.0x must be first run or compiled in Visual FoxPro 5.0 in order to be modified in Visual FoxPro 5.0.

Steps to Reproduce Behavior

Use the following steps to demonstrate the behavior in the Form Designer:

1. Create a form in Visual FoxPro 3.0b.

2. Add a command group to the form.

3. In the Click method of each command button, add a WAIT WINDOW command.

4. Close the Form Designer and save the form.

5. Modify the form in Visual FoxPro 5.

6. Attempt to view the click method code for each of the command buttons. They appear empty.

7. Run the form in Visual FoxPro 5.0, and click on the command buttons. No code is executed.

Use the following steps to demonstrate the behavior in the Class Designer:

1. Create a class in Visual FoxPro 3.0b based on CommandGroup:

         CREATE CLASS cmdgroup OF cmdgrp3 AS COMMANDGROUP
   

2. In the Click method of each command button, add a WAIT WINDOW command.

3. Close the Class Designer and save the class.

4. Instantiate the class in Visual FoxPro 5.0 by issuing the following commands in the Command window or from a program file:

         SET CLASSLIB TO cmdgrp3
         x=CREATEOBJECT('cmdgroup')
         x.command1.CLICK()
         RELEASE x
   

   Note that no WAIT WINDOW is executed.

5. Modify the class:

         MODIFY CLASS cmdgroup OF cmdgrp3
   

6. Attempt to view the Click method code for each of the command buttons. They will appear empty.

   COMPILE CLASSLIB cmdgrp3