Q169111: PRB: Error Performing DODEFAULT Function on Base Class Method

Article: Q169111
Product(s): Microsoft FoxPro
Version(s): WINDOWS:5.0,5.0a
Operating System(s): 
Keyword(s): kbcode kbvfp kbvfp500 kbvfp500a
Last Modified: 11-DEC-1999

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The information in this article applies to:

- Microsoft Visual FoxPro for Windows, versions 5.0, 5.0a 
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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 
Technology        : kbVFPsearch kbAudDeveloper kbVFP500 kbVFP500a
Version           : WINDOWS:5.0,5.0a
Issue type        : kbprb

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