Visual C++ OLE Automation and VB's GetObject

Vince Pajerski -- vp360@ansyspo.ansys.com
Tuesday, February 20, 1996


     MSVC 4.0 (with service pack 1)
     MFC 4.0
     Windows NT 3.51 (not using the new shell with service pack 3)
     VB 4.0


Hi all,

I'm trying to access an existing automation object using VB and the 
GetObject function call. The automation server is written with VC++ . The 
call looks like this:

dim obj as Object
set obj = GetObject(, "Myapp.document")  // doesn't work


However, this code will execute:

dim obj as Object
set obj = GetObject("", "Myapp.document")  // works but trashes my document


Every time the 1st two lines execute,  VB complains that it can't create the 
object.  According to the documentation, it should return a reference to the 
active object and not create a new one.  The app I built from VC++ is a 
standard app generated from App Wizard and only exposes one method to the 
world.

I tried the same code with an Excel object and it worked fine.  The code to 
do this looks like:

dim obj as Object
set obj = GetObject(,"Excel.Application")

This works provided that Excel is up and running already, so I am lead to 
believe that something is wrong with either my code and/or the type library. 



Can anyone help?

if(Penguins != Stanley_Cup)
  something_went_terribly_wrong( );

Vince Pajerski
ANSYS Inc.
e-mail vpajerski@ansys.com

---

Ludek Slegr -- ludek.slegr@munich.ixos.de
Wednesday, February 21, 1996

[Mini-digest: 2 responses]

Hi Vince,

> I'm trying to access an existing automation object using VB and the
> GetObject function call. The automation server is written with VC++ . The
> call looks like this:
>
> dim obj as Object
> set obj = GetObject(, "Myapp.document")  // doesn't work

I will tell you, what you probably know already. It looks like the Server is 
not running or the class does not match the entry in the registry.

Regards,
Ludek
-----From: Victor Garcia Aprea 

        Hi,
              1) Why are you using GetObject instead of CreateObject. Are
you creating a new object, right?
              2) If you wrote the code for the OLE Automation server, are
you calling AddRef() before returning a reference to the object? Because if
you forget to call AddRef() on your new object and then return a reference
to it, when it goes out of scope then VB can crash itself and actually it
sure will do that (happen to me).

                I wrote my own OLE Auto server and I tested it from VB 4. At
the first time I got some problems but know I have a bit of experience. If
you continue having problems maybe I can help you if you explain the problem
in more detail.

                                        Victor Garcia Aprea.

---

| Вернуться в корень Архива |