Effect of DoEvents in Visual Basic OLE Server DLLs (138063)
The information in this article applies to:
- Microsoft Visual Basic Standard Edition, 32-bit, for Windows 4.0
- Microsoft Visual Basic Professional Edition, 16-bit, for Windows 4.0
- Microsoft Visual Basic Professional Edition, 32-bit, for Windows 4.0
- Microsoft Visual Basic Enterprise Edition, 16-bit, for Windows 4.0
- Microsoft Visual Basic Enterprise Edition, 32-bit, for Windows 4.0
This article was previously published under Q138063 SUMMARY
A DoEvents statement inside a inproc OLE server might cause reentrancy
problems.
MORE INFORMATION
If you make a call to an inproc OLE server by say, clicking a command
button on a form on some client and that call uses DoEvents, Visual Basic
will yield to process other pending messages. If now due to some user
action another inproc call or the same one is made to the same DLL server,
there is nothing to prevent the DLL code from being re-entered. This might
cause unforeseen problems depending on the situation, so this scenario is
best avoided. Another problem with DoEvents in a DLL is that you are
processing messages for the host (.exe file) in your message loop. The host
may have special code in its message loop to handle some messages, and
problems may occur when this code is not executed.
| Modification Type: | Major | Last Reviewed: | 12/9/2003 |
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| Keywords: | KB138063 |
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