On Tuesday, 26 January 2016 at 15:53:39 UTC, Manu wrote:
So, you're saying that if you have an 'I' pointer, which may be
implemented by a C++ class, it still needs to be able to cast
to Object, and therefore fails? I wonder if a C++ class could
somehow be promoted to a D class when being derived in D, by
having an Object placed somewhere.
It helps that Object is a just a handful of virtual methods.
On Tuesday, 26 January 2016 at 16:25:35 UTC, Benjamin Thaut wrote:
For a D class the first entry in the vtable is the classinfo.
Thus the problem if you derive a D class from a extern(C++)
base class. I don't see any way to actually fix this, adjusting
the this pointer won't help. Once you derive a D class from a
extern(C++) base class it is no longer a fully functional D
class. For example monitor (e.g. synchronized methods) won't
work.
Calypso has "hybrid" D classes inheriting from C++, with this
layout:
- D vptr
- D monitor
{ start of C++ class }
- C++ vptr
- C++ fields...
- might be other vptr and fields if the C++ class has more than
one base
{ end of C++ class }
- D fields...
and when downcasted to the C++ base class the "this" pointer gets
adjusted to point towards the start of the C++ class.
