PRB: Application Appears Then Exits to Operating System

• Microsoft Visual FoxPro for Windows, versions 3.0, 5.0

SYMPTOMS

A Visual FoxPro .EXE file appears briefly, and then it exits to the operating system.

CAUSE

The main program is a screen or menu, and no READ EVENTS command has been issued. In Visual FoxPro, the Command window provides a place for your application to wait for the next command. Because the Command window is unavailable in a run-time application, the .EXE file has no wait state to anticipate keyboard input, so the application returns to the operating system.

RESOLUTION

A READ EVENTS command or a modal form will provide a wait state for your application.

STATUS

This behavior is by design.

MORE INFORMATION

Adding a READ EVENTS to a menu

If the main program in your project is a menu, a READ EVENTS command should be added to the menu as follows:

1. In the Menu Builder on the View menu, click General options.

2. Select the Cleanup check box. In the Cleanup code window, add this code:

         READ EVENTS
   

3. Add a Quit option to the menu that contains this command:

         CLEAR EVENTS
   

Creating a Modal Form or Formset

The easiest way to provide a wait state for a form or formset is to set the WindowType property to 1 - Modal at design time.

This may be undesirable if you want to run other forms from within the current form or formset.

Creating a Program that Issues a Read Events

The form or formset can be run from within a program that issues a READ EVENTS. For example:

1. Create a program containing this code:

         DO FORM <formname>
         READ EVENTS
   

2. Save this program, and make it the main program in your project.

3. Add a command button to the form. Add the following code in its Click event:

         CLEAR EVENTS
         THISFORM.RELEASE
   

Adding a READ EVENTS to a form or formset

If you do not want to create a wrapper program that runs the form and issues a read events command, you can add the appropriate code to the form or formset itself. For example:

1. Add a new property to the form or formset named RdEventsFlag. Set the value of this property to false (.F.).

2. In the Activate method of the form or formset, add this code:

         IF !THISFORM.RdEventsFlag
            READ EVENTS
            THISFORM.RdEventsFlag = .T.
         ENDIF
   
   

3. Add a command button to the form. Add the following code to its click event:

         CLEAR EVENTS
         THISFORM.RELEASE
   

Steps to Reproduce Behavior

1. Create a quick form.

2. Create a new project, and add the form to the Documents tab.

3. Build an executable from the project.

4. Exit Visual FoxPro, and run the executable. The menu appears briefly; then the executable returns to the operating system shell.

REFERENCES

Visual FoxPro Professional Features Guide, Chapter 9.