Re: VS2010 and HINSTANCES
"David Ching" <dc@remove-this.dcsoft.com> wrote in message
news:A4B0B11D-7081-4A87-B8AB-072F221E1E76@microsoft.com...
Initializing static variables has worked reliably for me....
There *are* circumstances when it doesn't, but not very often. Nevertheless
I've been caught by it and am wary.
However it is all fixed now,...
But the 0xcccccccc is said to be used for *local* variables, not static
members. I'm not sure if that is significant, but it may mean the scope of
your variable is not what it appears to be?
.... and it wasn't that.
I would set a breakpoint...
Yes. Among other places, I set a breakpoint in some initialisation code,
and found it wasn't being called. The missing initialisation was actually
in a DLL. Searching for references to it in the VS 2008 code and the VS
2010 revealed a line I had inadvertently over looked in the DllMain (telling
it to remember its hInstance in a static class variable). The variable I
should have been initialising was therefore NULL (as it was declared so) and
code which included if( hInstance) { ... } was failing to run, resulting in
another local hInstance NOT being initialised, resulting in the problem.
I now have written out 1000 times:
"When creating a new MFC solution and importing old code, check very
carefully ALL the functions which the App Wizard provides for you!
Especially DllMain!"
I looked very hard but couldn't find one. I think once I wrote something
like:
if ( hInst && hInst != 0xcccccccc )
AfxSetResourceHandle(hInst);
I wondered about that, but explicitly checking for 0xcccccccc seemed wrong.
I immediately think that in the next version of the compiler, the debugger
might initialise to 0xabcdabcd or some other number, and start worrying
about hostages to fortune. Now if there was something like
#define UNINITIALISED_VARIABLE 0xcccccccc
in the Microsoft headers, I'd consider it fair game to check against
UNINITIALISED_VARIABLE (especially inside passages with _DEBUG defined).
I haven't checked to see if there is such a thing.
Which fixed my logic but of course I went back and cleaned that up prior
to shipping. BTW, does your code work OK in Release mode (where
uninitialized variables are left uninitialized and not set to 0xcccccccc)?
I would think it would work randomly well based on whether hInst happened
to be initialized to 0 or not.
It would have crashed, but I found the bug before checking the release
version.
Dave
--
David Webber
Mozart Music Software
http://www.mozart.co.uk
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