bearophile wrote:
Walter Bright:
No, it is done with one indirection.<
If even Andrei, a quite intelligent person that has written big books on C++,
may be wrong on such a basic thing, then I think there's a problem.
It can be good to create an html page that explains how some basic things of D are
implemented in the front-end. Such page can also contain box & arrow images
that show how structures and memory are organized for various of such data
structures.
Such html page is useful for both normal programmers that want to understand
what's under the hood, and for people that may want to fix/modify the front-end.
Bye,
bearophile
I agree, the ABI documentation on digitalmars.com is far from complete,
I had to learn a lot of it through trial and error. What was especially
confusing was the interface reference vs the interface info vs the
interface's classinfo vs the referenced object, I wrote an internal
wrapper struct to make most of the casts go away:
struct Interface {
Object object() const {
return cast(Object)(cast(void*)&this - interfaceinfo.offset);
}
immutable(InterfaceInfo)* interfaceinfo() const {
return **cast(InterfaceInfo***)&this;
}
immutable(ClassInfo) classinfo() const {
return interfaceinfo.classinfo;
}
}
immutable struct InterfaceInfo {
ClassInfo classinfo;
void*[] vtbl;
ptrdiff_t offset;
}
These two made implementing D internals a whole lot easier! I think only
InterfaceInfo is in druntime (and its confusingly named Interface in there).
