Variant array element -> class object (or com server) paramaray function = pointer, not value?

From: Lee Benfield (lee_at_sp_benf_am.org)
Date: 05/21/04

  • Next message: Ken Halter: "Re: Variant array element -> class object (or com server) paramaray function = pointer, not value?" 
    Date: Fri, 21 May 2004 21:55:00 +0100

    (x posted, as I'm working with excel 97, but this exibits on VB6)

    When you pass an element of a variant array to a class function
    (and ONLY a class function, non class function and class subs do not
    exhibit this), you end up with something which looks suspiciously
    like a pointer instead of the correct value. Is there a relevant KB
    article for this? (can't find one).

    Note that this requires at least 2 values in the paramarray.

    Can anyone point me at either a fix or an explanation?

    Example:

    >> module:========
    Private Sub showbug()
         Dim ca As clsA
         Set ca = New clsA

         Dim v
         v = Array(1, 2, 3, 4)
         Call ca.testSub(v(0), v(1), v(2), v(3))
         Call ca.testFn(v(0), v(1), v(2), v(3))
         call ca.testFn(v(2))
    End Sub
    clsA:==========
    Public Sub testSub(ParamArray foo() As Variant)
         Debug.Print Join(foo, ",")
    End Sub

    Public Function testFn(ParamArray foo() As Variant) As Variant
         Debug.Print Join(foo, ",")
         testFn = "Oops"
    End Function
    <<==============

    Output:

    1,2,3,4
    1556816,1556832,1556848,1556864

    (note the incrementing addresses - swap array elements for predictable
    behaviour!)

    I've tested that this also exhibits when passing to a com server,
    ([vararg] [in] SAFEARRAY(VARIANT) *, [out, retval] VARIANT *)
    incorrect elements end up as VT_I4 regardless of input type.

    At my wits end!

    Thanks.

    Lee.

  • Next message: Ken Halter: "Re: Variant array element -> class object (or com server) paramaray function = pointer, not value?"