Re: MFC and number of times COM intialized

From:
"David Ching" <dc@remove-this.dcsoft.com>
Newsgroups:
microsoft.public.vc.mfc
Date:
Fri, 20 Jul 2007 14:16:35 GMT
Message-ID:
<7t3oi.40108$Um6.29965@newssvr12.news.prodigy.net>
"one-trick-pony" <worldofpain.aamir@gmail.com> wrote in message
news:1184937416.597873.59090@n2g2000hse.googlegroups.com...

Greetings,

I was told that COM should be intialized only once in application or
once per thread. I was reading SDK samples and it says:

"CoInitialize could be called more than once in an application. The
first successful call will return NOERROR; subsequent successful calls
will return S_FALSE. Each successful nested call to CoInitialize must
be matched with a corresponding call to CoUninitialize. CoUninitialize
frees resources the COM libraries have allocated and unloads the
libraries themselves. "

I have a working MFC based application which intializes COM only once
and it works great. So my conclusion is that it can be done multiple
times too. That is, both approaches are correct. Please, if someone
can verify that if both approaches are correct. Thanks.


I think you need to call CoInitialize() or better yet
CoInitializeEx()/OleInitialize(), on the thread which performs the COM. I
once created a secondary ui thread that used a CDHtmlDialog (which uses a
CWebBrowser control), and this required me to call OleInitialize() from the
secondary thread. In my case, calling it once per app was not enough. COM
initialization and shutdown seems to be a per-thread (not per-process)
thing.

-- David

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