Re: AfxBeginThread() with a function in the main class - C / C++ / MFC Discussion Boards

AfxBeginThread() with a function in the main class

Johpoke3-Aug-07 5:59

3-Aug-07 5:59

This is allways something wich i have had trouble with, usualy i end up doing some ugly trick to make it work.. But this time i cant.. (well ive been spending around 3 days trying..) I need a thread which is connected to the main class of my MFC Dialog based application. I looked at Code Project:Using AfxBeginThread...[^] In which i end up createing a new static function that seems to work with some functions.. But when i tried calling the function i wanted it to run, it couldnt since it wasnt a static function.. So i tried making it a static function, but then i got loads of error messages...

So how would i go about creating and running a thread that is connected to the main class (like "CThreadDemoDlg::OnStart()" ) ?

The function doesnt need any params or other advanced features, maybe i should start it using a differnt function?

Or how should i go about this?

thanks!

PS: Im not really that good at the terminology for c++, or c++ programming itself, so nothing too hightech or advanced unless its a must do..

//Johannes

Re: AfxBeginThread() with a function in the main class

led mike3-Aug-07 6:13

led mike

3-Aug-07 6:13

Well this is not a MFC thread but it can work in MFC applications and/or maybe it will help give you the idea

/** Win32 CreateThread class wrapper */
class base_w32thread{
protected:
    HANDLE    _handle;
    DWORD    _dwTID;
    base_w32thread():_handle(0), _dwTID(0L){}
    virtual ~base_w32thread()=0;

public:
    bool start(LPSECURITY_ATTRIBUTES psecattrs = NULL, DWORD dwCreateFlags = 0L);
    operator HANDLE(){ return _handle; }
protected:
    virtual void run()=0;
    virtual void onEndThread(){}
    static long WINAPI threadfnc( LPARAM lp);
};

#include "StdAfx.h"

#include "base_w32thread.h"
#include <winbase.h>
#include <assert.h>

base_w32thread::~base_w32thread(){}

/** start the thread */
bool base_w32thread::start(LPSECURITY_ATTRIBUTES psecattrs, DWORD dwCreateFlags){

    assert( !_handle);
    if( _handle)
        return false;

    _handle = ::CreateThread( psecattrs, 0, 
        (LPTHREAD_START_ROUTINE)threadfnc, this, dwCreateFlags, &_dwTID);
    return (_handle)?true:false;
}
/** Thread function */
long WINAPI base_w32thread::threadfnc( LPARAM lp){

    assert( lp);
    base_w32thread* pThis = (base_w32thread*)lp;
    if( pThis)
        pThis->run();

    pThis->_handle = 0L;        // thread exited
    pThis->onEndThread();
    return 0L;
}

Re: AfxBeginThread() with a function in the main class

David Crow3-Aug-07 6:15

David Crow

3-Aug-07 6:15

What's wrong with:

void CMyDlg::Process( void )
{
    // do whatever you need to in this non-static method
}
...
/* static */ UINT CMyDlg::Process( LPVOID pParam )
{
    CMyDlg *pDlg = (CMyDlg *) pParam;
 
    pDlg->Process();
 
    return 0;
}
...
AfxBeginThread(Process, this);

"A good athlete is the result of a good and worthy opponent." - David Crow

"To have a respect for ourselves guides our morals; to have deference for others governs our manners." - Laurence Sterne

Re: AfxBeginThread() with a function in the main class [modified]

Mark Salsbery3-Aug-07 6:20

Mark Salsbery

3-Aug-07 6:20

The thread procedure accepts a void pointer which you can pass when you create the thread.

If you pass a pointer to an object of a class then you will have access to that object from the
thread. If the thread proc is a static member function of that class, you have complete access
(to public/protected/private members).

class CThreadDemoDlg : public CDialog
{
<font face="Courier New">   static UINT __cdecl MyThreadProc(LPVOID pParam);</font>   
protected:
   <font face="Courier New">CWinThread *pAnotherThread; 
</font>public:
   void SomeThreadStarterFunc();
};

<font face="Courier New">void </font><font face="Courier New">CThreadDemoDlg::</font><font face="Courier New">SomeThreadStarterFunc()
{
   pAnotherThread = AfxBeginThread(&</font><font face="Courier New">CThreadDemoDlg::MyThreadProc, this);
}

UINT __cdecl </font><font face="Courier New">CThreadDemoDlg::MyThreadProc(LPVOID pParam)
{
   </font><font face="Courier New">CThreadDemoDlg *pMyDlg = (</font><font face="Courier New">CThreadDemoDlg *)pParam</font><font face="Courier New">;

   ...</font><font face="Courier New"><font><font></font></font>
}</font>

Mark

Last modified: 25mins after originally posted --

Mark Salsbery
Microsoft MVP - Visual C++
Java | [Coffee]

Re: AfxBeginThread() with a function in the main class

Johpoke3-Aug-07 6:39

Johpoke

3-Aug-07 6:39

Thank you all for you great replies Smile | :)

Im trying out Mark's code right now, but its giving me an error message i really dont understand..

On this line:
CThreadDemoDlg *pMyDlg = (CThreadDemoDlg *pParam);

error C2146: syntax error : missing ')' before identifier 'pParam'
error C2059: syntax error : ')'

Ive renamed all the classes to the class on my program, so its not that... What could this be?

Thank you all!

Smile | :)

//Johannes

Re: AfxBeginThread() with a function in the main class

Mark Salsbery3-Aug-07 6:45

Mark Salsbery

3-Aug-07 6:45

Fixed. Sorry about that Smile | :)

It should be

<font face="Courier New">CThreadDemoDlg *pMyDlg = (</font><font face="Courier New">CThreadDemoDlg *)pParam</font><font face="Courier New">;</font>

Mark Salsbery
Microsoft MVP - Visual C++
Java | [Coffee]

Re: AfxBeginThread() with a function in the main class

Johpoke3-Aug-07 6:52

Johpoke

3-Aug-07 6:52

Ah yes now it compiles, thanks.

But when i add a function to it (one that is connected to CThreadDemoDlg) i get the cant call a nonstatic member function..

error C2352: 'CThreadDemoDlg::SomeFunction' : illegal call of non-static member function
see declaration of 'SomeFunction'

So how should i go about calling the function?

thanks again!

//Johannes

Re: AfxBeginThread() with a function in the main class

David Crow3-Aug-07 6:54

David Crow

3-Aug-07 6:54

Johpoke wrote:
So how should i go about calling the function?

Can you at least bother to show the code that is producing this error? Roll eyes | :rolleyes:

"A good athlete is the result of a good and worthy opponent." - David Crow

"To have a respect for ourselves guides our morals; to have deference for others governs our manners." - Laurence Sterne

Re: AfxBeginThread() with a function in the main class

Johpoke3-Aug-07 6:59

Johpoke

3-Aug-07 6:59

Doh,

UINT __cdecl CThreadDemoDlg::MyThreadProc(LPVOID pParam)<br />
{<br />
   CThreadDemoDlg *pMyDlg = (CThreadDemoDlg *)pParam;<br />
<br />
   MyFunction();<br />
<br />
   return 1;<br />
}

It looks exactly like that, except the names are different

//Johannes

Re: AfxBeginThread() with a function in the main class

David Crow3-Aug-07 7:05

David Crow

3-Aug-07 7:05

Hint: Ever wonder what pMyDlg is being used for?

"A good athlete is the result of a good and worthy opponent." - David Crow

"To have a respect for ourselves guides our morals; to have deference for others governs our manners." - Laurence Sterne

Re: AfxBeginThread() with a function in the main class [Solved]

Johpoke3-Aug-07 7:12

Johpoke

3-Aug-07 7:12

I was thinking i must use it to gain access to the rest of the functions so i like tried :: on it but that didnt work. Now i tried -> on it and all my functions come up Big Grin | :-D

Thanks alot for the help. The only downside with this is im probably gonna have to go through loads of old programs and get rid of their ugly methods and add this. But i guess its worth it Big Grin | :-D

Thanks again Smile | :)

//Johannes

Re: AfxBeginThread() with a function in the main class

Ahmad Al-Maraghi4-Aug-07 1:50

Ahmad Al-Maraghi

4-Aug-07 1:50

u don't understand the problem Frown | :(

Re: AfxBeginThread() with a function in the main class

led mike3-Aug-07 7:08

led mike

3-Aug-07 7:08

Johpoke wrote:
but its giving me an error message i really dont understand..

You don't understand a syntax error message but you are working with multi threading *sigh* different day same old garbage

Re: AfxBeginThread() with a function in the main class

Mark Salsbery3-Aug-07 7:32

Mark Salsbery

3-Aug-07 7:32

led mike wrote:
*sigh* different day same old garbage

This[^] should cheer you up.

Beer | [beer]

Mark Salsbery
Microsoft MVP - Visual C++
Java | [Coffee]

Re: AfxBeginThread() with a function in the main class

led mike3-Aug-07 7:43

led mike

3-Aug-07 7:43

Good Grief Sigh | :sigh:

Happy Friday Beer | [beer]

Re: AfxBeginThread() with a function in the main class

Johpoke3-Aug-07 7:59

Johpoke

3-Aug-07 7:59

lol, that dancing dude is funny/weird.

My program now works perfectly, thank you all for you help.

How does one make that dude anyway? i cant find him...

//Johannes

Re: AfxBeginThread() with a function in the main class

led mike3-Aug-07 8:09

led mike

3-Aug-07 8:09

Johpoke wrote:
My program now works perfectly

If it works, do it.

If it works, do it it works

  seems to work      probably
     ^                  ^
If it   works, do it it    works

  seems to work      probably
     ^                  ^
If it   works, do it it    works
	
(and might work again)

Cogito ergo sum

(although, admittedly, that is an assumption)

Re: AfxBeginThread() with a function in the main class

Mark Salsbery3-Aug-07 8:14

Mark Salsbery

3-Aug-07 8:14

Johpoke wrote:
How does one make that dude anyway? i cant find him...

It's right next to the Beer | [beer]

one.

With a little ingenuity, you'll find it Smile | :)

Mark Salsbery
Microsoft MVP - Visual C++
Java | [Coffee]

Re: AfxBeginThread() with a function in the main class

Johpoke3-Aug-07 8:27

Johpoke

3-Aug-07 8:27

Maybe its like a gold-member only emotion. or maybe it doesnt like me...

Ah well doesnt matter im happy anyway Smile | :)

//Johannes

Re: AfxBeginThread() with a function in the main class

Mark Salsbery3-Aug-07 8:34

Mark Salsbery

3-Aug-07 8:34

Johpoke wrote:
Maybe its like a gold-member only emotion.

Nope. I was so proud when I found it all by myself, since I know nothing about web programming Smile | :)

Mark Salsbery
Microsoft MVP - Visual C++
Java | [Coffee]

Re: AfxBeginThread() with a function in the main class

Johpoke3-Aug-07 8:40

Johpoke

3-Aug-07 8:40

//Johannes

Re: AfxBeginThread() with a function in the main class

Mark Salsbery3-Aug-07 8:57

Mark Salsbery

3-Aug-07 8:57

Mark Salsbery
Microsoft MVP - Visual C++
Java | [Coffee]

Re: AfxBeginThread() with a function in the main class

Mark Salsbery3-Aug-07 8:13

Mark Salsbery

3-Aug-07 8:13

Mark Salsbery
Microsoft MVP - Visual C++
Java | [Coffee]

PostThreadMessages lost in DLL

PaulCammy3-Aug-07 5:54

PaulCammy

3-Aug-07 5:54

I have a DLL that has a class derived from CWinApp.

I have another class in the DLL that needs to trigger an asynchronous process within that same DLL. Since the DLL has no window I use PostThreadMessage to trigger the process as follows:

<code>void CMyClass::TriggerAsyncProc() const
{
AfxGetApp()->PostThreadMessage(WMU_MYMSG, 0, 0L) ;
}</code>

In my class derived from CWinApp, I have tried two different methods to trap WMU_MYMSG. The first was to override PreTranslateMessage, and the second was to try to use the CWinApp message map (via ON_THREAD_MESSAGE).

The DLL is being used by a dialog application, and the TriggerAsyncProc is definately sending the message because PostThreadMessage(WMU_MYMSG, 0, 0L) returns non-zero.

The only thing I can think of is that my message is going through the message map of the dialog application instead of my class derived from CWinApp in the DLL.

Please can someone tell me why I'm losing the message, and suggest either how I correct this or an alternative method?

Thanks.
Confused | :confused:

Re: PostThreadMessages lost in DLL

Mark Salsbery3-Aug-07 6:07

Mark Salsbery

3-Aug-07 6:07

This doesn't sound like it would work.

A DLL that has a CWinApp object is supported, but that CWinApp object doesn't have its own message pump.
I wouldn't expect any messages to be processed in the DLL's CWinApp object unless you've tweaked something
to do so.

Here's what the docs state about this situation:

"Note that the CWinApp::Run mechanism does not apply to a DLL, because the application owns the main message pump.
If your DLL brings up modeless dialogs or has a main frame window of its own, your application's main message pump must
call a DLL-exported routine that calls CWinApp::PreTranslateMessage."

Mark

Mark Salsbery
Microsoft MVP - Visual C++
Java | [Coffee]

Use Ctrl+Left/Right to switch messages, Ctrl+Up/Down to switch threads, Ctrl+Shift+Left/Right to switch pages.