On Thursday, 28 June 2018 at 18:43:11 UTC, Andre Pany wrote:
Hi,
I try to write a binding for the GRPC core. There is a struct
which has some ugly fields:
(https://github.com/grpc/grpc/blob/master/src/core/lib/surface/call.cc#L229)
struct grpc_call {
gpr_refcount ext_ref;
gpr_arena* arena;
...
grpc_core::ManualConstructor<grpc_core::SliceBufferByteStream>
sending_stream;
grpc_core::OrphanablePtr<grpc_core::ByteStream>
receiving_stream;
ManualConstructor is defined as:
https://github.com/grpc/grpc/blob/50cecca24d4826dea4595b514a332fca5783074b/src/core/lib/gprpp/manual_constructor.h#L168
template <typename Type>
class ManualConstructor {
public:
Type* get() { return reinterpret_cast<Type*>(&space_); }
const Type* get() const { return reinterpret_cast<const
Type*>(&space_); }
My C / C++ knowledge is very limited and I also do not know how
much D matured regarding C / C++ integration. Is it possible to
write a binding in D for these constructs or isn't it supported
by D?
Kind regards
André
No, unfortunately D cannot interface with C templates, only C++
templates. But just by coincidence this is C++ source code (and
so the templates).
So it is possible but there is few catches.
- template functions/methods could be inlined by compiler, which
means you may (or may not) have to implement it in D (either
copy-paste and adapt, or make own ABI compatible implementation)
- most of the methods in this particular template is purely C++
specific convenience helpers, all of this isn't strictly needed
in D, just for example operator-> could simply be replaced with
alias this.
- the only data member in this template is the
std::aligned_storage, which you can probably ignore completely
and instead just use fixed-size ubyte[] array with align, again
just make struct with alias this and align its content same way
as aligned_storage does.
And much more-more other things to keep in mind.
But the most important thing, are you absolutely sure this is a
part of the public API and not the implementation specific
internals? Because normally you don't #include anything other
than .h* files, this is a source file, and it is not even sits in
the include folder.
