Problem of passing MFC pointers between DLL and EXE

There is a problem when pointers to MFC class objects are passed
between an application and a Dll.
Does any have a solution ?

0
7/12/2006 8:14:20 AM
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> There is a problem when pointers to MFC class objects are passed
> between an application and a Dll.

What problem is that? It works fine. Can you be more specific?

----
Ajay

0
ajaykalra (6842)
7/12/2006 1:21:24 PM
<charfeddine_ahmed@yahoo.fr> wrote in message 
news:1152692060.794841.20610@p79g2000cwp.googlegroups.com...

> There is a problem when pointers to MFC class objects are passed
> between an application and a Dll.
> Does any have a solution ?

This is usually caused by static linking of MFC or not making the DLL's 
MFC-extension DLLs.

Just a guess.

Dave
-- 
David Webber
Author MOZART the music processor for Windows -
http://www.mozart.co.uk
For discussion/support see
http://www.mozart.co.uk/mzusers/mailinglist.htm


0
dave1 (356)
7/12/2006 1:27:10 PM
> This is usually caused by static linking of MFC or not making the DLL's
> MFC-extension DLLs.

I dont know if static linking of MFC causes problems like this but
certainly I have had no issues (such as this) when using a Regular MFC
dll along with a MFC moudle and/or MFC extension DLL. 

---
Ajay

0
ajaykalra (6842)
7/12/2006 2:07:11 PM
Are the pointers to UI objects and the DLL running code in another thread? 
That always causes a problem.

Tom

<charfeddine_ahmed@yahoo.fr> wrote in message 
news:1152692060.794841.20610@p79g2000cwp.googlegroups.com...
> There is a problem when pointers to MFC class objects are passed
> between an application and a Dll.
> Does any have a solution ?
> 


0
tserface (3861)
7/12/2006 2:33:18 PM
<charfeddine_ahmed@yahoo.fr> wrote in message 
news:1152692060.794841.20610@p79g2000cwp.googlegroups.com...
> There is a problem when pointers to MFC class objects are passed
> between an application and a Dll.
> Does any have a solution ?
>

It's not a problem if both the .exe and .dll use MFC as a shared library. 
Both the .exe and .dll need to share the same instance of MFC so that MFC 
objects passed between the two are managed correctly.  For example, MFC 
keeps a map of CWnd derived objects with the HWND they encapsulate.  So if 
you don't use shared MFC libraries, and pass a pointer to a CWnd-derived 
class to the other module, then it's instance of MFC won't be able to find 
the HWND to that CWnd class, since the map is stored in the first module's 
instance of MFC.  But if you use shared MFC, then both the .exe and the .dll 
use the same map, and there is no problem.

-- David


0
dc2983 (3206)
7/12/2006 2:47:56 PM
"Ajay Kalra" <ajaykalra@yahoo.com> wrote in message 
news:1152713231.776564.303650@b28g2000cwb.googlegroups.com...

>> This is usually caused by static linking of MFC or not making the DLL's
>> MFC-extension DLLs.
>
> I dont know if static linking of MFC causes problems like this but
> certainly I have had no issues (such as this) when using a Regular MFC
> dll along with a MFC moudle and/or MFC extension DLL.

My understanding is the same as that expressed by David Ching.

Dave
-- 
David Webber
Author MOZART the music processor for Windows -
http://www.mozart.co.uk
For discussion/support see
http://www.mozart.co.uk/mzusers/mailinglist.htm



0
dave1 (356)
7/12/2006 3:16:21 PM
Depends.  For example, if you use static linking of the MFC runtime, there's a possibility
that you have multiple heaps and multiple maps, and the world falls apart.  But for
objects that don't involve object maps, or if you never use static linking, I'm not aware
of any problems.
					joe

On 12 Jul 2006 01:14:20 -0700, charfeddine_ahmed@yahoo.fr wrote:

>There is a problem when pointers to MFC class objects are passed
>between an application and a Dll.
>Does any have a solution ?
Joseph M. Newcomer [MVP]
email: newcomer@flounder.com
Web: http://www.flounder.com
MVP Tips: http://www.flounder.com/mvp_tips.htm
0
newcomer (15975)
7/12/2006 3:29:17 PM
This is the problem of mapped objects.  It isn't unique to DLLs; a different thread
running in the exectuable itself will exhbit the same problems if it tries to do any
operation that involves a handle map.  It doesn't "always" cause problems; it only causes
problems if a handle map is involved.
					joe

On Wed, 12 Jul 2006 07:33:18 -0700, "Tom Serface" <tserface@msn.com> wrote:

>Are the pointers to UI objects and the DLL running code in another thread? 
>That always causes a problem.
>
>Tom
>
><charfeddine_ahmed@yahoo.fr> wrote in message 
>news:1152692060.794841.20610@p79g2000cwp.googlegroups.com...
>> There is a problem when pointers to MFC class objects are passed
>> between an application and a Dll.
>> Does any have a solution ?
>> 
>
Joseph M. Newcomer [MVP]
email: newcomer@flounder.com
Web: http://www.flounder.com
MVP Tips: http://www.flounder.com/mvp_tips.htm
0
newcomer (15975)
7/12/2006 3:47:12 PM
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