Re: MFC and threads

"Doug Harrison [MVP]" <>
Wed, 04 Apr 2007 15:40:28 -0500
On Wed, 04 Apr 2007 12:43:24 -0500, David Wilkinson <>

Yes, this is how I would do it also. IMHO, prejudice against
SendMessage() often leads to unnecessarily complex solutions.

The main thing the more complex solution has going for it is that it makes
it easier to multiplex events by replacing the WFSO with WFMO. Also, a
thread blocked by interthread SendMessage can still respond to sent
messages, so reentrancy issues may exist with SendMessage that cannot occur
with PostMessage/WFSO. However, since the sending thread apparently has no
windows, this is not a consideration. Note that the SendMessage approach
doesn't sacrifice the early return capability of the event approach,
because the target thread can use ReplyMessage in an equivalent way to
SetEvent. So there's little reason to use PostMessage/WFSO over
SendMessage. If you need to multiplex events, that's a reason to use
PostMessage/WFMO; for example, you may want the sending thread to be able
to detect a "quit" event.

Doug Harrison
Visual C++ MVP

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