(noob) Question about classes

**abachler** · 09-21-2007

I have a class that as part of its initialize function needs to start a thread that is specific to the instantiation of the class.

so for example

Code:

CClass* pClass;
 
pClass = new CClass();
 
pClass->Initialize();

and the Class function -

Code:

class CClass {
     private:
          HANDLE hThread;
          DWORD ThreadId;
     public:
          void Initialize();
          DWORD WINAPI Thread(LPVOID);
     };
 
CClass::Initialize(){
     hThread = CreateThread(NULL , 0 , &Thread , NULL , 0 , &ThreadId);
     return;
     }
 
CClass::Thread(LPVOID lParam){
     // thread code goes here
     return 0;
     }

My question is will the call to pClass->Initialize() properly start a thread based on the class specific function?

**Wraithan** · 09-21-2007

If you aren't sure, you can always specify a member function via 'this', ie this->Thread.

**CornedBee** · 09-21-2007

No, it won't, and simply compiling would have told you that. You can't pass a member function where a C callback is expected.

I recommend you use Boost.Thread for threading, as it handles member functions (via bind) properly, without you having to jump through the hoop of stub functions.

**Wraithan** · 09-21-2007

Didn't think about that, I don't typically use win32 so it didn't cross my mind lol.

**Codeplug** · 09-21-2007

Here's an example of a Win32 thread "object" implementation that can "bind" to class member or regular functions. It's a couple of years old, but not too far from what I still use today. Contains a bit of hoop-jumping so it'll work with MSVC 6.0.

http://cboard.cprogramming.com/showthread.php?t=59695

gg

**abachler** · 09-21-2007

Could you please explain to me how Boost is going to fix the issue of starting a thread based on a member function? No offence, but I dont throw black boxes at problems.

Added -

On looking through Codeplugs code, I noticed that he declares the thread function using the static keyword, this fixed the problem with my compiler throwing an error. Thanks CP.

Now of course its giving link errors, but I think thats just because I put the functions in the header file instead of in their own source file.

Added- moving the functions out of the header fixed that problem too.

**CornedBee** · 09-22-2007

Boost.Thread contains an internal proper starting point for the thread, which is passed a pack holding the starting point you specified. Because this pack is, basically, a Boost.Function object, it can call any callable C++ entity: normal functions, bound member functions, complicated bindings, or in fact any function object you want.
This comes with a tiny bit of overhead, but compared to the thread starting overhead of the OS, it is negligible.

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