PRB: Error Performing DODEFAULT Function on Base Class Method

• Microsoft Visual FoxPro for Windows, versions 5.0, 5.0a

SYMPTOMS

An error occurs when performing a DODEFAULT function on a Visual FoxPro base class KeyPress method.

STATUS

Microsoft has confirmed this to be a problem in the Microsoft products listed at the beginning of this article.

MORE INFORMATION

An error occurs when performing a DODEFAULT function to a Visual FoxPro base class method. The DODEFAULT function appears to be referencing an object other than the one in which it is running.

In the code below, the DODEFAULT code is located in the KEYPRESS method of a Form. Pressing the TAB key when the cursor is in the first TextBox of the sample below causes the VALID method of the TextBox to execute but the VALID method of Form appears to be running in addition to the TextBox VALID and a "Property VALUE is not found" error occurs. The Form object does not have a VALUE property. Suspending the program after the error occurs and checking the value of "THIS" verifies that the object reference is the Form rather than the TextBox.

Steps to Reproduce Behavior

1. Run the sample code below and press the TAB key to move to the next object.

   
         ****Start of Code
   
         frmTestForm = CREATEOBJECT("MyForm")
         frmTestForm.SHOW
         READ EVENTS
   
         **************************************************
         *-- ParentClass:  basform
         *-- BaseClass:    form
         DEFINE CLASS MyForm AS BASFORM
           PROCEDURE KEYPRESS
           LPARAMETERS NKEYCODE, NSHIFTALTCTRL
   
           && Do not comment the PROCEDURE, ENDPROC or LPARAMETERS lines
           && Comment the following two lines only
   
           WAIT WINDOW "Form Key Press - Child Class"
           DODEFAULT(NKEYCODE, NSHIFTALTCTRL)
   
           ENDPROC
         ENDDEFINE
         *
         *-- EndDefine: MyForm
         **************************************************
         *-- ParentClass:  form
         *-- BaseClass:    form
         DEFINE CLASS BasForm AS FORM
           TOP = 10
           LEFT = 23
           DOCREATE = .T.
           CAPTION = "Test Form"
           KEYPREVIEW = .T.
           NAME = "frmForm1"
   
           ADD OBJECT txtTEXT1 AS TEXTBOX WITH ;
             HEIGHT = 23, ;
             LEFT = 84, ;
             TOP = 24, ;
             WIDTH = 100, ;
             NAME = "txtText1"
   
           ADD OBJECT txtTEXT2 AS TEXTBOX WITH ;
             HEIGHT = 23, ;
             LEFT = 84, ;
             TOP = 84, ;
             WIDTH = 100, ;
             NAME = "txtText2"
   
           ADD OBJECT cmdCOMMAND1 AS COMMANDBUTTON WITH ;
             TOP = 216, ;
             LEFT = 276, ;
             HEIGHT = 27, ;
             WIDTH = 84, ;
             CAPTION = "Close", ;
             NAME = "cmdCommand1"
   
           ADD OBJECT lblLabel1 as LABEL with;
              TOP = 20, ;
           LEFT = 200,;
              CAPTION = "Press the TAB key"
   
             *!* PROCEDURE KEYPRESS
             *!* LPARAMETERS NKEYCODE, NSHIFTALTCTRL
   
             *!* WAIT WINDOW "Form Key Press - Parent Class"
             *!* DODEFAULT(nkeycode, nshiftaltctrl)
             *!* ENDPROC
   
             * Uncomment the above code and comment the contents of
             * the Keypress procedure (Comment the 2 lines of code that
             * are identified to be commented out within the Keypress
             * procedure, which are the lines that start with "WAIT WINDOW"
             * and "DODEFAULT". Do not comment out the PROCEDURE line nor the
             * LPARAMETERS line nor the ENDPROC line) in the BasForm
             * Class definition and the error will not occur.
   
             PROCEDURE txtTEXT1.VALID
               IF EMPTY(THIS.VALUE)
                 WAIT WINDOW "Text1 Valid"
               ENDIF
             ENDPROC
   
             PROCEDURE cmdCOMMAND1.CLICK
               THISFORM.RELEASE()
               CLEAR EVENTS
             ENDPROC
   
         ENDDEFINE
         *
         *-- EndDefine: basform
         ************************************************** 

Additional query words:

Keywords : kbcode kbVFp kbVFp500 kbVFp500a FxprgClassoop
Version : WINDOWS:5.0,5.0a
Platform : WINDOWS
Issue type : kbprb