PRB: @...GET...NAME Object References Change with Read Level

ID: Q156178

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

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

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.

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&amp;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 FxprgClassoop FxprgRead
Version : WINDOWS:3.0,3.0b,5.0,6.0
Platform : WINDOWS
Issue type :