DLL will not unload...

[Paul Squires]

Hi Everyone,

I am using a PB DLL/6 created DLL in Visual Basic. When I run
my project in the VB IDE the DLL loads but it appears that when
I quit running my project the DLL stays loaded. This always
occurs - not only if I break out of the VB program prematurely.

Having the DLL remain in memory is a problem because when I restart
running the program again the DLL retains its info from the last
time thus returning error codes to me.

Has anyone else noticed this type of behavior when using Win32
DLLs in the VB IDE. If I quit VB the DLL unloads. It seems like
the VB IDE is determining when the DLL should unload and not
my program.

I have confirmed that the DLL stays loaded between compiles by
using a DLL spy program that lists running DLLs.

Any help is appreciated.

Thanks,




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Paul Squires
mailto:[email protected][email protected]</A>

[Edwin Knoppert]

All the time.
Be sure you attach your windowclasses to the dll, not the exe! (VB-IDE)

Use a proper unload, not the stop button.
Be sure? unload VB.

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[John Petty]

It's been that way since VB3 and PB/DLL1.1, if a PB DLL is called with a declare then it stays resident until the VB IDE is closed

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[Paul Squires]

Okay, I have found a fix.

In VB's unload event I call a function in my DLL (UnloadDLL). All
that function does is use the DLL's hInstance handle in a call
to the FreeLibrary API routine. The DLL unloads and is ready to
be used again.

All that is needed is for the VB programmer to remember to include
this call in the unload event.

Thanks,



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Paul Squires
mailto:[email protected][email protected]</A>

[Edwin Knoppert]

No, that not good.
The DLL is kept loaded because VB claims a reference to it somehow.

This is only when you have used a custom windowclass or *maybe* using a thread.

If the control is correctly unloaded from the form, the DLL WILL unload properly in the IDE.

Just be sure you terminate all 'connections' files etc..

That VB loads your DLL is logical.

I messed with this myself, i know it's something you do not clear up.
Tip: there's no need to unregister a windowclass.


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[Paul Squires]

Hi Edwin,

My DLL is a "helper" DLL. It just contains many functions that
are easier to perform in PB than VB. It does not contain any
windows, dialogs, message pumps, threads or anything like that.

The DLL does seem to unload because I used a DLL spy program that
lists all running DLL's and when I call the unload function the
DLL no longer shows in the list and I am able to restart the
VB program without any problems.

Maybe I am not understanding what it is you are trying to tell
me. Sorry.



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Paul Squires
mailto:[email protected][email protected]</A>

[Edwin Knoppert]

If it's for internall use, fine.
If you enable save files before run , you may encounter a GPF.

It's a simple test, place a msgbox in your libmain detach.
If it occurres while simply closing your app NOT using the stop button, it's all fine.


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