ATL Internals: Working with ATL 8

Tavares and his co-authors present a specialised guide to the latest version of Active Template Library. It's for the C++ programmer on a Microsoft machine, who is also familiar with the Component Object Model. The authors specifically state that you really do need expertise in the latter. The book deals with various legacy issues, mostly dating back to MFC, which is now largely deprecated. But there are also other aspects that are grubby and mostly unavoidable. For example, when dealing with character types, there is an abstraction called OLECHAR. Under Win32, it maps to wchar_t, while under Win16 [and the Mac] it maps to char. The need for this was due to the hardware improvements that took us from 16 bit CPUs to 32 bits. A transition that occurred mostly in the 80s. But for Microsoft, the legacy code remains in use. So there has to be low level logic that maps the character type to an actual appropriately sized memory allocation. By the way, don't think this issue is confined to Microsoft. C code from that era that was developed for Unix machines, and which might still be in use, often has a similar problem. C macros dealing with this are a notorious source of porting errors. The text deals with many other aspects of ATL. Some, like collections and enumerations, are very cleanly done. These classes are inherently meant to be high level abstractions. And the C++ code examples that use these are very easy to follow. The discussion of this also includes some sample Visual Basic code. (Most of the book has C++ code.)