Microsoft KB Archive/149049

= PRB: Compiled In-Process Server Used Before IDE Server =

Article ID: 149049

Article Last Modified on 6/28/2004

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APPLIES TO


 * Microsoft Visual Basic 4.0 Standard Edition
 * Microsoft Visual Basic 4.0 Professional Edition
 * Microsoft Visual Basic 4.0 32-Bit Enterprise Edition

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This article was previously published under Q149049



SYMPTOMS
A request for an object provided by both a compiled OLE server dynamic-link library (DLL) and an instance of the OLE server running in the Visual Basic for Windows integrated design environment (IDE) is filled by the compiled DLL.



WORKAROUND
It is possible to test the execution of what will become an OLE DLL in the IDE when you have a previously compiled DLL. To accomplish this functionality temporarily unregister the previously compiled DLL using Regsvr32.exe. Then reregister the DLL by using Regsvr32.exe. For example:

Unregister the previously compiled DLL as follows:

regsvr32.exe -u DLLName.DLL

Reregister the DLL as follows:

regsvr32.exe DLLName.DLL

If you make a new DLL while still working, Visual Basic for Windows registers it when the DLL is made with the "Make OLE DLL" command.

Steps to reproduce problem
 Start an instance of the 32-bit edition of Visual Basic 4.0 for Windows. Click Class Module on the Insert menu to add a class module to the project.  Change the following properties on the new class module to the following: Instancing: 2 - Creatable Multiuse Public:    True   Add the following code to the class module: Public Sub Test MsgBox "In DLL" End Sub  Click Module on the Insert menu to insert a new code module.  Add the following code to the code module: Public Sub Main 'do nothing End Sub </li> Click Options on the Tools menu to open the Options dialog box. Switch to the Project tab and change the following settings:

Startup Form: Sub Main

Project Name: DLLandIDE

Startmode: OLE Server

</li> Click "Make OLE DLL File..." on the File menu to create a compiled OLE DLL.</li> Click Options on the Tools menu to again open the Options dialog box. Switch to the Project tab and type in the name of the DLL generated in step 8 in the Compatible OLE Server text box.</li> Click "Make OLE DLL File..." to recompile the DLL.</li> Change the line of code in the Test subroutine contained in the class module from "In DLL" to "In IDE."</li> Press F5 or click Start on the Run menu to run the server in the IDE.</li>  Start another instance of the 32-bit edition of Visual Basic for Windows, and add the following code in the Form_Click event to the default form, Form1: Private Sub Form_Click Dim MyObj As Object

Set MyObj = CreateObject("DLLandIDE.Class1") MyObj.Test End Sub </li> Step through the code in the client program and see that the text of the message box displayed by the Test method contains "In DLL" and not "In IDE."</li></ol>

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MORE INFORMATION
Generally, OLE automation clients receive objects from an instance of an OLE server running in the Visual Basic for Windows IDE before they receive objects from a compiled server. Visual Basic for Windows accomplishes this functionality by temporarily adding or modifying registry keys when an IDE server is started and then restoring the original settings when the server is stopped. This was done to make debugging of OLE servers as easy as possible. However, if a server has previously been compiled into an OLE DLL, then objects are provided from that compiled DLL before they are provided by a server running in the IDE.

The reason for this behavior is rooted in the search path OLE uses when attempting to create an object. This search path is listed below:


 * Inprocess server of same bitness
 * 32-bit local server (for 16-bit clients under a Microsoft Win32 operating system)
 * Local server of same bitness
 * Local server of other bitness

Servers running in the IDE are always out-of-process. When a request for an object is made, OLE encounters the previously compiled in-process server before it encounters the one running in the IDE, and so it creates the object from that DLL.

Keywords: kbprb KB149049

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