PRB: Passing Arrays by Reference to OLE Objects Not Supported

• Microsoft Visual FoxPro for Windows, versions 3.0, 3.0b, 5.0, 5.0a
• Microsoft Visual FoxPro for Macintosh, version 3.0b

SYMPTOMS

Microsoft Visual FoxPro does not support passing arrays by reference to OLE objects.

STATUS

This behavior is by design.

MORE INFORMATION

Steps to Reproduce Behavior

1. Place the following code in a program file and add the program file to a project named OLETest. Compile the project into an OLE DLL or EXE named OLETest.

         DEFINE CLASS ARRAYTEST AS CUSTOM OLEPUBLIC
         NAME = "arraytest"
   

         PROCEDURE DOIT
            PARAMETER MYARRAY
            EXTERNAL ARRAY MYARRAY
            INSERT INTO FOO (ONE,TWO,THREE,FOUR) VALUES ;
               (MYARRAY[1],MYARRAY[2],MYARRAY[3],MYARRAY[4])
            MYARRAY [1] = "100"
            MYARRAY [2] = "200"
            MYARRAY [3] = "300"
            MYARRAY [4] = "400"
   
            USE CURDIR() + "foo.dbf"
            INSERT INTO FOO (ONE,TWO,THREE,FOUR) VALUES ;
               (MYARRAY[1],MYARRAY[2],MYARRAY[3],MYARRAY[4])
         ENDPROC
   
         PROCEDURE INIT
            SET UDFPARMS TO REFERENCE
            CREATE TABLE FOO ;
               (ONE C(10),TWO C(10), THREE C(10), FOUR C(10))
         ENDPROC
   
         ENDDEFINE
   
   
   

2. After the OLE file is compiled, run the following code:

         CLEAR
         CLEAR ALL
         DIMENSION MYARRAY[4]
         MYARRAY(1) = "1"
         MYARRAY(2) = "2"
         MYARRAY(3) = "3"
         MYARRAY(4) = "4"
         OX = CREATEOBJECT("OLEtest.arraytest")
         OX.DOIT(@MYARRAY)
         ?OX.Name
         ?"MyArray from Calling Program"
         DISPLAY MEMORY LIKE MYARRAY
         RELEASE OX
         RELEASE MYARRAY
         USE foo
         BROWSE NOWAIT
   

3. Notice the first record of table "Foo" contains the values placed in the array by the calling program. The second record contains the values PROCEDURE DOIT placed in the array. The DISPLAY MEMORY LIKE MYARRAY command, however, contains the original values of the array. Even though it appears that we are passing the array by reference to the OLE object, Microsoft Visual FoxPro is passing it by value.

Keywords          : FxinteropOle VFoxMac vfoxwin kbcode
Version           : MACINTOSH:3.0b; WINDOWS:3.0,3.0b
Platform          : MACINTOSH WINDOWS
Issue type        : kbprb