On comp.lang.c++.moderated, Peter Lundblad wrote:

  • I also don't see the need for gcnew. Why not use placement new, i.e.:
    T^ h = new (CLI::gc) T(14);
    This would require an extension allows placement new overloads to return something other than void* and a standard way to get to the raw storage where to construct the object. That extension, however, could be useful for other things as well, i.e. a new that returns a smart pointer so you don't have to have a public constructor on the smart pointer taking a raw pointer which is dangerous.

There are several reasons why we didn't use a form of placement new.

One reason is that we wanted to leave a door open in case in the future we wanted to allow placement and class-specific forms of gcnew. Having a parallel gcnew expression and operator best serves leaving that door open.

Another reason is that existing libraries, including GC libraries, already use placement forms of new, and so many of the possible placement names are taken. In particular, new (gc) X; is already taken by the Boehm collector. Yes, I know you suggested CLI::gc instead of plain gc, but in practice I'm still concerned that enough people are liable to frequently write using namespace CLI; (actually stdcli) to make this problematic.

Still another is one you cite: It's easier to teach that "the type of a new-expression (and operator new) is a *" today, and that "the type of a gcnew-expression is a ^".

Finally, a minor reason is that gcnew is slightly less typing than new (gc) or new (cli), and moderately less typing than new (stdcli::gc).