On Wednesday, 7 October 2015 at 15:13:40 UTC, Jonathan M Davis
wrote:
std.typecons.RefCounted aside, it's quite possible as-is to
implement smart pointers in D with structs, thus providing
deterministic destruction for reference types. I don't know why
RefCounted wasn't implemented to work with classes, and I don't
know why Walter and Andrei think that something like DIP 74 is
necessary to support ref-counting.
There's a lot of hassles with a wrapper, the biggest blocker
being how it interacts with inheritance.
interface Base {}
class Foo : Base {}
void test(RefCounted!Base b) {}
RefCounted!Foo foo = initialized;
test(foo);
What happens? Well, you could alias this to Base... but what
about to Object? We'd need multiple alias this to get it all
working right, and then it'd still be kinda a pain.
Also, what about covariant method overriding? Base class returns
RefCounted!this and child class does too... will it be accepted?
Library refcounting is cool and great for a great many things,
but it doesn't play well with classes at all, inheritance just
makes it too complicated.
The magic of dip74 is that most the language remains the same so
those cases are already covered.
