Comparing CWinApp and main()
Scott Bloom -- sbloom@cris.com
Saturday, January 04, 1997
Environment: NT 4.0, Visual C++ 4.2b
I"m working on a conversion of a couple MFC Dialog Apps. All these
really do is start a bunch of server threads; The dialog allows the user
to shutdown, as well as keep CWinApp from terminating immediately
by creating a main window.
I'm converting these to services, and trying to decided if I need
any of the CWinApp related services. This new service app
will not need resources, but we will probably want access to
MFC classes and objects.
How much (if any) overhead is there when deriving your application
class from CWinApp as opposed to declaring a main() function?
What are the "gotchas" of either option?
Thanks,
Scott
Mike Blaszczak -- mikeblas@nwlink.com
Sunday, January 05, 1997
At 15:41 1/4/97 -0800, Scott Bloom wrote:
>Environment: NT 4.0, Visual C++ 4.2b
>How much (if any) overhead is there when deriving your application
>class from CWinApp as opposed to declaring a main() function?
You need to have a CWinApp object in either case, unless you're only
going to use the most trivial members of the most trivial MFC classes.
Since not having a CWinApp object doesn't make much sense, it's not
reasonable to make a comparison of efficiency or size between something
that doesn't work and something that does.
.B ekiM
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Scott Bloom -- sbloom@cris.com
Monday, January 06, 1997
>You need to have a CWinApp object in either case, unless you're only
>going to use the most trivial members of the most trivial MFC classes.
>Since not having a CWinApp object doesn't make much sense, it's not
>easonable to make a comparison of efficiency or size between something
>that doesn't work and something that does.
Is this because the static instance environment (HINSTANCE) aren't set
up correctly or another more obscure (to me) reason?
Thx,
Scott
Mike Blaszczak -- mikeblas@nwlink.com
Monday, January 06, 1997
At 00:28 1/6/97 -0800, Scott Bloom wrote:
>>You need to have a CWinApp object in either case, unless you're only
>>going to use the most trivial members of the most trivial MFC classes.
>>Since not having a CWinApp object doesn't make much sense, it's not
>>easonable to make a comparison of efficiency or size between something
>>that doesn't work and something that does.
>
>Is this because the static instance environment (HINSTANCE) aren't set
>up correctly or another more obscure (to me) reason?
Yes. MFC maintains lots of information for you on a per thread and
per module basis. If you've not initialized MFC (eg, you don't have
a CWinApp or CWinApp-derived object) you can make MFC sick. Sometimes,
you can get away without it, but you normally need it.
There are three or four KB articles on this subject.
.B ekiM
http://www.nwlink.com/~mikeblas/
Why does the "new" Corvette look like a 1993 RX-7?
These words are my own. I do not speak on behalf of Microsoft.
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