On Friday, 15 May 2015 at 19:44:29 UTC, Jonathan M Davis wrote:
So, while I don't know how we're going to be handling STL types (I don't even know what the current state of C++ state support is, since it keeps improving), I really don't see why there's value in supported inheritance with value types. It would just be begging for bugs - which is why native D types don't support it.
I'm talking about support for C++ idioms in frontend code, so satisfactory interfacing with C++ can be done, native D types can stay as they are.
C++ value types are designed to be used as value types and usually provide automatic memory management via RAII and scoped destruction. Without RAII you have a more serious risk of resource leaks or code cluttered with delete operators, also using value types as D classes results in non-idiomatic code resembling more Java than D or C++, which can alienate C++ programmers and is confusing overall. See an example of such code: https://github.com/Syniurge/Calypso/blob/master/tests/calypso/qt5/qt5demo.d
Inheritance in C++ is not always for polymorphism, often it's just functionality inheritance, so if needed slicing can be prevented by preventing upcasts.
