Re: multi-thread problem

From:

"Scott McPhillips [MVP]" <org-dot-mvps-at-scottmcp>

Newsgroups:

microsoft.public.vc.mfc

Date:

Thu, 15 Jun 2006 22:28:26 -0400

Message-ID:

<#tnNxyOkGHA.5108@TK2MSFTNGP02.phx.gbl>

cdg wrote:

I think I got the code correctly written for the problem in the previous
post. I just created an object of the ActiveX class. However, I am getting
one error message now, that I am not sure how to correct. It is a problem
with the function being "static", and involving the result from the ActiveX
Prg.

error: illegal reference to data member 'CThreadTestDlg::lResult' in a
static member function

UINT CThreadTestDlg::Thread1(LPVOID lParam)
{
CThreadTestDlg* pDlg = (CThreadTestDlg *)lParam;

ActxCtrl m_xActxCtrl; //****Added this line****

m_xActxCtrl.Open(); // open ActxCtrl

lResult = m_xActxCtrl.MemFunction();

m_xActxCtrl.Close(); // close ActxCtrl

pDlg->PostMessage(UWM_THREAD_FINISHED, (WPARAM)0, (LPARAM) lResult);

return 0;
}

As you have learned, the thread function must be static. This is
required by the operating system.

A static function cannot access class members. This is a required by
the C++ language. But lResult is a class member.

In your above trivial problem it appears that there is no need to have
lResult be a class member. So make it a local variable instead.

The more general solution to the static thread function needing access
to class members was illustrated in the example you tried to copy
earlier, that used pDlg->Thread1(). But I don't think you understood
the technique, so it is best avoided for now if you can.

--
Scott McPhillips [VC++ MVP]