I like programming with WTL and ATL. It's straight forward, clean and quite frankly, simple. I've worked a little with attributed ATL projects and attributes make certain functions a lot simpler.

I needed to recode an ActiveX component recently to work around Vista's IE protected mode. I decided to work with attribtued ATL. Since several dialogs were involved, I decided to drag in WTL to simplify the dialog code. That's when the problems began.

I didn't know this, but attributed ATL projects drag in atlstr.h, via the header file atlplus.h. You need to define _WTL_NO_CSTRING before including atlmisc.h. Otherwise, your component will attempt to compile WTL::CString and ATL::CString. The results are "unpredictable", but generally not fun to resolve.

Here's a reference: WTL CString Class Implemented with the Standard C++ Library

I've reproduced the key items:

1. WTL::CString is not compiled if you #define _WTL_NO_CSTRING before #include <atlmisc.h>
2. You will get ATL::CString support if you #include <atlstr.h> before #include <atlapp.h>
3. When ATL::CString is supported, WTL::CString should not be compiled.
4. If rule 2 does not apply, you will get WTL::CString support for classes defined after #define _WTL_USE_CSTRING
5. If rule 2 does not apply, you will get WTL::CString support for classes defined after #include <atlmisc.h>

Here's the order you need to use. Other headers should follow these four.