History
COM objects can also be created with Microsoft Foundation Classes (MFC), but this leads to larger binaries that require support DLLs. ATL, on the other hand, is a more lightweight alternative in situations where the graphical user interface parts of MFC are not required. In ATL version 7 (Visual Studio 2003), which directly succeeded version 3 (Visual Studio 6.0), a number of MFC classes like CString were made available in ATL, or more precisely moved to an ATLMFC common layer which is shared by both libraries. ATL version 7 also introduced attributes in C++ in an attempt to provide something similar to CLI attributes, however these have not been particularly successful, and have been deemphasized in ATL version 8 (Visual Studio 2005); the various wizards no longer generate them by default. Version 7 also introduced new string conversion classes. On July 28, 2009, Microsoft released a patch to ATL to fix a bug that could allow ActiveX controls created using ATL to be vulnerable to a remote code execution security flaw. Since Visual Studio 2013, ATL code in Visual C++ 2013 is static, eliminating the DLL.Support classes
ATL includes many RAII classes to simplify management of COM types. The most commonly used classes include: *CComPtr general-purpose smart-pointer,
* CComBSTR BSTR wrapper,
* CComVariant VARIANT wrapper, and
* CComSafeArray SAFEARRAY wrapper.
Compiler COM support
Although not formally part of ATL, Microsoft Visual C++ also includes additional C++ RAII classes to simplify management of COM types. These ''compiler COM support'' classes can be used as replacement for or in combination with ATL, and includes: *_com_ptr_t smart-pointer that decorates the COM interface name with a "Ptr" suffix,
* _bstr_t BSTR wrapper,
* _variant_t VARIANT wrapper, and
* _com_errorMicrosoft MSDNSee also
* ATL Server *References
External links