Calling D from C++

[Loopback]

On 2011-07-19 12:39, Loopback wrote:
> On 2011-07-19 05:46, Johann MacDonagh wrote:
>>>
>>> What is the best method to accomplish this, and are there any
>>> limitations with this method (do I have to allocate the class with
>>> malloc instead etc.)?
>>
>> Your C++ class "Base" is not compatible with your D "Foo" class. The
>> v-tables are not guaranteed to be identical. I'm not even sure if D's
>> thiscall is the same as C++'s thiscall. It's just not going to work.
>> Most languages don't support this. This is why we use C bindings.
>> Everyone supports C ;)
>>
>> Now, you can do something like this:
>>
>> struct Foo
>> {
>> int x;
>> float y;
>> }
>>
>> extern(C) void* GetNewFoo()
>> {
>> // Note: Don't use new here otherwise the GC may clean it up
>> return cast(void*) core.memory.GC.malloc(Foo.sizeof);
>> }
>>
>> extern(C) float Foo_DoSomething(Foo* foo)
>> {
>> return foo.x + foo.y;
>> }
>>
>> extern(C) void FreeFoo(Foo* foo)
>> {
>> core.memory.GC.free(foo);
>> }
>>
>> I haven't tried this, but something like this should work. Structs are
>> inherently compatible between languages. Of course, you won't be able to
>> do any kind of polymorphism.
>>
>> Does this help?
>
> Very interesting!
>
> This might help depends; are you able to have structures with functions?
> Are they still analogous if you implement them?
>
> Also, how come the class-interface inheritance didn't work to
> communicate with C++. Is the "Interface to C++" doc's outdated?
>
> "Calling D Virtual Functions From C++"
>
> http://www.digitalmars.com/d/2.0/cpp_interface.html
I noticed that function seems to work functions with structures.
Are there any restrictions worth knowing or is it just like any other
structure when D and C++ communicate?

Can I have private variables, public, properties etc?

And just not to forget, why the C++ and interface class didn't work?