PRB: ERROR "<formname> not an object" When Accessing Form

ID: Q129402

3.00 WINDOWS

The information in this article applies to:

Microsoft Visual FoxPro for Windows version 3.0

SYMPTOMS

Accessing a form causes the error message "Unknown member <formname>" to be displayed.

CAUSE

If a form is modal, the program pauses when it's displayed. A common reaction is for the user is to close the form to allow the program to continue execution. However, if the code that subsequently runs refers to any properties of the form, the error message is displayed because the form is out of scope (closed).

WORKAROUND

The WindowType property controls whether the form is modeless (the default) or modal. Setting the WindowType property for the form or formset in the DEFINE CLASS code to 0 (zero - modeless), or not including the WindowType property (causing a default of 0) resolves the problem.

STATUS

This behavior is by design.

MORE INFORMATION

Because they are modal, the program below pauses after the two forms appear. When the forms are closed, the program will continue after the FrsMyset.show command. However, because the forms are closed, the error "Unknown member FRMMYFORM1" is displayed.

   PUBLIC FrsMyset, FrmMyform1
   FrsMyset = CREATEOBJECT("myformset")
   FrsMyset.show

   FrsMyset.FrmMyform1.addobject("MyButton","commandbutton")
   FrsMyset.FrmMyform1.MyButton.left=40
   FrsMyset.FrmMyform1.MyButton.visible=.t.

   DEFINE CLASS myformset AS formset
      windowtype = 1    && this is the offending statement
      ADD OBJECT FrmMyform1 AS form
      FrmMyform1.caption="Form 1"
      add object FrmMyform2 as form
      FrmMyform2.caption="Form 2"
      FrmMyform2.autocenter=.t.

      PROCEDURE show
         =MESSAGEBOX("Show Method")
      ENDPROC
   ENDDEFINE

The WindowType property controls whether the form is modeless (the default) or modal. If the form is modal, the user must close the form before accessing any other elements of your application's user interface (see below).

WindowType

setting    Description

0           Modeless.
1           Modal. No other Form objects can become active and
            the menu is inactive. All Form objects in the FormSet
            are active.
2           Read. The FormSet behaves as if it were activated by
            the READ command. Execution stops on the Show method
            or DO FORM command. When the Form is deactivated,
            execution continues. (Included for backward compatibility.)
3           Read Modal. The FormSet behaves as if it were activated
            by a READ command's   MODAL clause. Program execution stops
            at the Show method or the DO FORM command. Any Form objects
            specified in the WindowList property are available, but other
            Form objects and the menu are not available. (Included for
            backward compatibility.)

Removal of the WindowType property (or setting it to 0) in the class definition allow the windows to be modeless and thus allow program execution to continue after the windows are displayed.

Additional reference words: 3.00 VFoxWin model errmsg window KBCategory: KBSubcategory: FxtoolFormdes

Keywords          : kberrmsg FxtoolFormdes 
Version           : 3.00
Platform          : WINDOWS