The New C++

Visual C++ 2005 completely reworks the interaction between C++ and the .NET Common Language Runtime. Specifically, it introduces a “New C++” syntax for managed code that is designed to fix shortcomings of the Managed Extensions to C++ (commonly referred to as Managed C++, or MC++), introduced in 2002 as part of Visual C++ .NET.

Shown here are two code samples that perform the same function, using the older Managed C++ syntax (left) currently supported in Visual C++ 2003 and the New C++ syntax (right) planned for Visual C++ 2005. Both samples define a very simple class that represents a credit account and which has an integer property that represents the account’s credit limit.

As shown in the code sample on the left, Managed C++ uses the ANSI standard method of adding new keywords to the C++ language: all new keywords began with two underscores (__property, for example). The sample illustrates several disadvantages of this approach. First, the presence of leading underscores in the keywords __gc and __property on lines 1, 4, 5, and 10 is unattractive and makes the code hard to read. It is also hard to write: developers complained, as Visual C++ architect Stanley Lippman said, “Particularly after the 2000th time they type __gc.” Second, the credit limit property is not integrated into the language: its definition appears to be two unrelated functions on lines 4 and 5 and setting its value is done by what appears to be a function call on line 11.