Q156178: PRB: @…GET…NAME Object References Change with Read Level

Article: Q156178
Product(s): Microsoft FoxPro
Version(s): WINDOWS:3.0,3.0b,5.0,6.0
Operating System(s): 
Keyword(s): kbvfp300 kbvfp500 kbvfp600
Last Modified: 14-DEC-1999

-------------------------------------------------------------------------------
The information in this article applies to:

- Microsoft Visual FoxPro for Windows, versions 3.0, 3.0b, 5.0, 6.0 
-------------------------------------------------------------------------------

SYMPTOMS
========

You may see the following error when referencing objects created using READ-
type code with the NAME keyword (DEFINE WINDOW...NAME and @...GET...NAME):

  "Unknown member <objectname>"

This occurs in situations with multiple READ levels.

CAUSE
=====

When objects are created using the NAME keyword, each one is added to a page
within a PageFrame control. The page number corresponds to the READ level.

WORKAROUND
==========

Reference objects in the following manner:

  <FormName>.Pageframe1.Page<rdlevel()>.<ObjectName>.Property

See the MORE INFORMATION section below for details.

STATUS
======

This behavior is by design.

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

The NAME keyword creates an object reference for controls created with the
DEFINE WINDOW, @ ... GET, and @ ... EDIT commands, allowing you to manipulate
these objects' properties, events, and methods.

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

1. Run the following code from a program (.prg) file:

     * Start of code example
     *
     DEFINE WINDOW Wind1 AT 0, 0 SIZE 15, 50 TITLE "1st Screen" ;
        SYSTEM FLOAT NAME oForm1
     ACTIVATE WINDOW Wind1
     @ 1, 10 SAY "Press Enter to go to 2nd screen"
     @ 3, 11 SAY "1st screen get " GET lcGet1 SIZE 1, 17 ;
        DEFAULT " " WHEN when1() VALID valid1() NAME loGet1
     READ

     RELEASE WINDOW Wind1

     FUNCTION when1
        oForm1.Pageframe1.Page1.loGet1.Value = "123"
     ENDFUNC

     FUNCTION valid1
        DO Screen2
     ENDFUNC

     FUNCTION Screen2

        DEFINE WINDOW Wind2 AT 0, 0 SIZE 10,55 TITLE "2nd Screen ";
           SYSTEM FLOAT NAME oForm2
        ACTIVATE WINDOW Wind2
        @ 3, 6  SAY "2nd screen get " GET lcGet2 SIZE 1, 17 ;
           DEFAULT " " WHEN When2() NAME loGet2
        READ

        RELEASE WINDOW Wind2
        CLEAR READ ALL
     ENDFUNC

     FUNCTION When2
        oForm2.Pageframe1.Page1.lo_Get2.Value = "123"
     ENDFUNC
     *
     * End of code example

2. Note that code in the When1 function successfully references the Value
  property of the @...GET command in the first screen. Press enter from 1st
  Screen to go to the second Screen.

3. The error "Unknown member LO_GET2" occurs as 2nd Screen appears. The
  following code refers to a nonexistant member since the object loGet2 is
  actually contained in oForm2.Pageframe1.Page2:

        oForm2.Pageframe1.Page1.loGet2.Value = "123"

A generic workaround for this behavior is to use the following code to determine
the current READ level and insert the current READ level into the object
reference with Macro Substitution. For example, change the code for the function
When2 in the code sample above to read as follows:

     * Start of code example
     *
     FUNCTION When2
        LOCAL lcPageNumber
        lcPageNumber=ALLTR(STR(RDLEVEL()))
        oForm2.Pageframe1.Page&lcPageNumber..loGet2.Value = "456"
     ENDFUNC
     *
     * End of code example

This stores the current READ level to lcPageNumber and substitutes it back into
the object reference. This allows the object loGet2 to be referenced regardless
of READ level.

REFERENCES
==========

For more information about using the NAME keyword with the DEFINE WINDOW and @
GET commands, please see the following article in the Microsoft Knowledge Base:

  Q138780 How to Use the Name Argument of an @...GET in Visual FoxPro

Additional query words: kbdse VFoxWin

======================================================================
Keywords          : kbvfp300 kbvfp500 kbvfp600 
Technology        : kbVFPsearch kbAudDeveloper kbVFP300 kbVFP300b kbVFP500 kbVFP600
Version           : WINDOWS:3.0,3.0b,5.0,6.0

=============================================================================

THE INFORMATION PROVIDED IN THE MICROSOFT KNOWLEDGE BASE IS PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND. MICROSOFT DISCLAIMS ALL WARRANTIES, EITHER EXPRESS OR IMPLIED, INCLUDING THE WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. IN NO EVENT SHALL MICROSOFT CORPORATION OR ITS SUPPLIERS BE LIABLE FOR ANY DAMAGES WHATSOEVER INCLUDING DIRECT, INDIRECT, INCIDENTAL, CONSEQUENTIAL, LOSS OF BUSINESS PROFITS OR SPECIAL DAMAGES, EVEN IF MICROSOFT CORPORATION OR ITS SUPPLIERS HAVE BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES. SOME STATES DO NOT ALLOW THE EXCLUSION OR LIMITATION OF LIABILITY FOR CONSEQUENTIAL OR INCIDENTAL DAMAGES SO THE FOREGOING LIMITATION MAY NOT APPLY.

Copyright Microsoft Corporation 1986-2002.