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Q129207: PRB: "Property Not Found" Occurs When Running Form

Article: Q129207
Product(s): Microsoft FoxPro
Version(s): WINDOWS:3.0
Operating System(s): 
Keyword(s): kberrmsg
Last Modified: 03-AUG-2000

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The information in this article applies to:

- Microsoft Visual FoxPro for Windows, version 3.0 
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SYMPTOMS
========

The following error message displays while you are running a form:

  Property Not Found

CAUSE
=====

The period (.) operator was used in conjunction with macro substitution to
reference a property that contains the name of an object. Because the compiler
recognizes the period as the macro terminator, it doesn't evaluate the remainder
of the line that contains the property.

WORKAROUND
==========

To work around this problem, add an additional period after the macro
substitution. The first period terminates the macro and the second allows the
compiler to reference the property.

For example, to fix the problem, refer to the "Steps to Reproduce Behavior"
section of this article, and replace the lines that use a single period to
reference properties with the following lines of code:

     This.&cOButton..Caption="Button"-cOldbNo && Originally used one period
     This.&cOButton..Picture=''

  *** ...

     This.&cButton..Caption=""                && These lines are farther
     This.&cButton..Picture='c:\vfp\fox.bmp'  && down in the example

NOTE: Macro substitution can usually be replaced by the superior EVALUATE()
function, but using EVALUATE() requires an additional line of code. In this
example, program execution is faster and the amount of executable code generated
by the compiler/linker is smaller. For example:

Instead of:

     This.&cOButton..Picture=''

Use:

     oRef=EVAL("THIS."+cOButton)
     oRef.Picture=''

STATUS
======

This behavior is by design.

MORE INFORMATION
================

Steps to Reproduce Behavior
---------------------------

The following program displays a form that contains three buttons (Button1,
Button2, and Button3). Macro substitution is used to modify the Picture and
Caption properties of these objects.

1. From the File menu, choose New. Select the Program option, and then choose
  the New File button.

2. Enter the following source code:

     oMyForm = CREATEOBJECT("MyForm")
     oMyForm.show
     READ EVENTS

     DEFINE CLASS MyForm AS FORM
        nCurrentb=1

        ADD OBJECT Button1 AS COMMANDBUTTON WITH ;
          top=1,left=1,height=2,width=10,caption="",picture='c:\vfp\fox.bmp'

        ADD OBJECT Button2 AS COMMANDBUTTON WITH ;
          top=7,left=1,height=2,width=10

        ADD OBJECT Button3 AS COMMANDBUTTON WITH ;
          top=13,left=1,height=2,width=10

        PROCEDURE Button1.Click
          This.Parent.ChangeProp(1)
        ENDPROC

        PROCEDURE Button2.Click
          This.Parent.ChangeProp(2)
        ENDPROC

        PROCEDURE Button3.Click
          This.Parent.ChangeProp(3)
        ENDPROC

        PROCEDURE ChangeProp
           PARAMETERS nNewbutton

          cOldbNo=''
          cNewbNo=''
          cOButton=''
          cButton=''

           * Clear .bmp on old button
           cOldbNo=ALLTRIM(STR(This.nCurrentb))
           cOButton="Button"-cOldbNo
           This.&cOButton.Caption="Button"-cOldbNo  && WILL NOT WORK
           This.&cOButton.Picture=''                && WILL NOT WORK

           * Display .bmp on new button
           cNewbNo=ALLTRIM(STR(nNewbutton))
           cButton="Button"-cNewbNo
           This.&cButton.Caption=""                 && WILL NOT WORK
           This.&cButton.Picture='c:\vfp\fox.bmp'   && WILL NOT WORK

           This.nCurrentb=nNewbutton
        ENDPROC
     ENDDEFINE

Additional query words: VFoxWin 3.00 akz

======================================================================
Keywords          : kberrmsg 
Technology        : kbVFPsearch kbAudDeveloper kbVFP300
Version           : WINDOWS:3.0

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