Q129871: PRB: "Object not a Collection" Trying to Read Array Element

Article: Q129871
Product(s): Microsoft Visual Basic for Windows
Version(s): WINDOWS:4.0
Operating System(s): 
Keyword(s): kbprogramming kbVBp400
Last Modified: 11-JAN-2001

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The information in this article applies to:

- Microsoft Visual Basic Standard Edition, 32-bit, for Windows, version 4.0 
- Microsoft Visual Basic Professional Edition, 16-bit, for Windows, version 4.0 
- Microsoft Visual Basic Professional Edition, 32-bit, for Windows, version 4.0 
- Microsoft Visual Basic Enterprise Edition, 16-bit, for Windows, version 4.0 
- Microsoft Visual Basic Enterprise Edition, 32-bit, for Windows, version 4.0 
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SYMPTOMS
========

If a public member of a class of type variant is assigned an array, you get the
following error message when trying to read an element of the array by directly
indexing the variant member:

  Object not a Collection.

This happens only if the instance of the class object is late bound; that is, the
instance is dimensioned "As Object."

RESOLUTION
==========

- Dimension the object instance as being of the exact type of the class, so
  that it is Early Bound.

-or-

- Index the variant member with another level of parenthesis. For example, in
  the "Steps to Reproduce Behavior" section of this article, use:

        Debug.Print x.arr()(0)

  Instead of:

        Debug.Print x.arr(0)

  This explicitly specifies that the variant holds an array.

STATUS
======

This behavior is by design.

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

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

1. Start a new project in Visual Basic. Form1 is created by default.

2. Choose Module from the Insert menu to add a new standard module (Module1)

3. Add the following code to Module1:

        Sub main()
           Dim a(2) As Integer
           a(0) = 5

           Dim x As Object
           Set x = New Class1

           x.arr = a
           Debug.Print x.arr(0)
        End Sub

4. Choose Class Module from the Insert menu to add a new class module (Class1).

5. Add the following code to Class1:

        Public arr As Variant

6. Press the F5 key to run the program. You will get the error message on the
  Debug.Print line.

Example Workaround
------------------

To work around the behavior, declare the object with a specific object type
instead of Object. In Step 3 above, replace:

     Dim x As Object

  with:

     Dim x As New Class1

Then change the Set statement into a comment. After making these changes, run the
program again. You should see a value of 5 in the Debug Window.

Additional query words:

======================================================================
Keywords          : kbprogramming kbVBp400 
Technology        : kbVBSearch kbAudDeveloper kbVB400Search kbVB400 kbVB16bitSearch
Version           : WINDOWS:4.0
Issue type        : kbprb

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