COM and variant woes

Hi there,

Got myself stuck pretty good this time, on COM/Automation. Here's the scenario.

Have myself a COM-INTERFACE:

BOM 11 > obj
#<COM interface I-ACAD-BLOCK-REFERENCE = 001B3074>


The IDL perspective on the interface can be seen here:
    [
      odl,
      uuid(D50215E2-500B-4302-9C0E-991399B6C749),
      helpstring("AutoCAD Block Reference Interface"),
      helpcontext(0x00010010),
      dual,
      oleautomation
    ]
    interface IAcadBlockReference : IAcadEntity {
        [id(0x00000001), propget, helpstring("Specify the X, Y, Z coordinate for insertion point of the block or use the Pick Point button to set X, Y, Z values simultaneously"), helpcontext(0x00010313)]
        HRESULT InsertionPoint([out, retval] VARIANT* insPoint);
        [id(0x00000001), propput, helpstring("Specify the X, Y, Z coordinate for insertion point of the block or use the Pick Point button to set X, Y, Z values simultaneously"), helpcontext(0x00010313)]
        HRESULT InsertionPoint([in] VARIANT insPoint);
        ...<etc>...
    };

When invoking the propget method, the returned value is meaningful (a 3D Autocad coordinate):

BOM 12 > (invoke-dispatch-get-property obj "insertionpoint")
#(0.0D0 0.0D0 0.0D0)


I'm stuck with the propput however, where I can't seem to supply the correct lisp object. The AutoCAD documentation on this method describes the input argument as a "Variant (three-element array of doubles)". Naively I tried this:

BOM 13 > (setq ins (make-lisp-variant '(:array :double) #(0.0D0 0.0D0 0.0D0)))
#S(LISP-VARIANT :TYPE (:ARRAY :DOUBLE) :VALUE #(0.0D0 0.0D0 0.0D0))

But to no avail:

BOM 14 > (invoke-dispatch-put-property obj "insertionpoint" ins)

Error: COM IDispatch::Invoke Exception  in "IAcadBlockReference::InsertionPoint" {80070057 - The parameter is incorrect.}  : NIL
  1 (abort) Return to level 0.
  2 Return to top loop level 0.


Nor incidentally, can I simply pass in what I got out:

BOM 15 > (invoke-dispatch-put-property obj "insertionpoint" #(0.0D0 0.0D0 0.0D0))

Error: COM IDispatch::Invoke Exception  in "IAcadBlockReference::InsertionPoint" {80070057 - The parameter is incorrect.}  : NIL
  1 (abort) Return to level 0.
  2 Return to top loop level 0.


Dead in the water here. Any insights/recommendations greatly welcomed.

Brian Connoy
COM and variant woes

Re: COM and variant woes
