Active Template Library

The Active Template Library (ATL) is a set of template-based C++ classes developed by Microsoft, intended to simplify the programming of Component Object Model (COM) objects. The COM support in Microsoft Visual C++ (MSVC) allows developers to create a variety of COM objects, OLE Automation servers, and ActiveX controls.

ATL is integrated with software wizards supplied with MSVC that facilitate automatic copy-and-paste programming for basic tasks, such as configuring the library's build options and setting up the primary structure of an ATL object definition. On the COM client side ATL provides smart pointers that deal with COM reference counting. The library makes heavy use of the curiously recurring template pattern and multiple inheritance.