Is D so powerfull ??

[Daniel Murphy via Digitalmars-d]

On 9/11/2015 5:54 PM, Jeremy DeHaan wrote:

>>
>> Didn't you say constructors and destructors are missing? What should
>> one do in those cases?

Constructors and destructors do not match the C++ ABI, but they are 
still generated, so they can only be called from the language they were 
written in.  So if you write your classes in D you must new and delete 
(or GC) them from D.  You can still create them from C++ (or create 
C++-written classes from D) if you use a forwarding function:

X makeX() { return new X(); }

>
> Additionally, should we use new in this case? Wouldn't new create a
> pointer to a C++ class? Or does it work differently for extern(c++)
> classes?

New in D will allocate a class instance on the GC heap and return a 
reference to it, just like when it's used with D classes.

These two functions have the same ABI:

// D

extern(C++) class X {}

extern(C++) void func(X x);

// C++

class X {}

void func(X *x);


You can find several examples of C++ interop in dmd's test\runnable\cppa.d