General Class Design Philosophy
The new home for Visual Studio documentation is Visual Studio 2017 Documentation on docs.microsoft.com.
The latest version of this topic can be found at General Class Design Philosophy.
Microsoft Windows was designed long before the C++ language became popular. Because thousands of applications use the C-language Windows application programming interface (API), that interface will be maintained for the foreseeable future. Any C++ Windows interface must therefore be built on top of the procedural C-language API. This guarantees that C++ applications will be able to coexist with C applications.
The Microsoft Foundation Class Library is an object-oriented interface to Windows that meets the following design goals:
Significant reduction in the effort to write an application for Windows.
Execution speed comparable to that of the C-language API.
Minimum code size overhead.
Ability to call any Windows C function directly.
Easier conversion of existing C applications to C++.
Ability to leverage from the existing base of C-language Windows programming experience.
Easier use of the Windows API with C++ than with C.
Easier to use yet powerful abstractions of complicated features such as ActiveX controls, database support, printing, toolbars, and status bars.
True Windows API for C++ that effectively uses C++ language features.
For more on the design of the MFC Library, see: