Hello Walter,
John Reimer wrote:
In D (windows) it would look like so (assuming you have done away
with the compilers internal detection of COM interfaces):
extern(C++) interface IUnknown:
{
extern(Windows):
int QueryInterface(nsIID* uuid, void **result);
int AddRef();
int Release();
}
I bet it would work fine and would be a good way to avoid the
special-cased interfaces providing COM support in D. Instead we've
special-cased for C++, which is, at least, a more general case. ;-)
There is one other problem. COM objects are not collected by the
garbage collector because they are reference counted. Deriving from
IUnknown means its a COM object which sets a flag in the ClassInfo,
directing the garbage collector to not collect it. In fact, COM
objects are allocated using malloc(). IUnknown.Release() uses free()
to deallocate them.
Okay, that is an important detail for me to know. But I assumed that a C++
interface must not be allocated in D either. In must acquire a pointer from
an external factory that handles the allocation outside of the gc range (C++
code must allocate/delete it's own objects).
This seems to me to be a somewhat equivalent process as for a COM object.
Is there a ClassInfo flag indicating no-gc-collection for extern(C++) interfaces
too?
-JJR
