January 02
Hi, everyone.

I would like to have an interface that can be implemented and/or used from C++ in D. One of the things I would like to keep is the nice feature of D dynamic arrays in terms of bounding checks and "length" property.

Let's assume:

extern (C++) interface ICppInterfaceInD {
  ref const(int[]) indices() const;
}

class A: ICppInterfaceInD {
  private int[] m_indices;

  extern (C++) ref const(int[]) indices() const {
    return m_indices;
  }
}

All I want is keeping const correctness like in C++ so no one can modify m_indices and use that as property within const pointer. I thought it may be passed to C++ as some struct of sort:

struct wrappedArrray(T) {
  size_t length;
  T* ptr;
}

but it just don't want to be friendly with me.

How should I rethink the interface with being D-way efficient when using that interface inside of D?

January 02
On 2018-01-02 17:48, Void-995 wrote:
> Hi, everyone.
> 
> I would like to have an interface that can be implemented and/or used from C++ in D. One of the things I would like to keep is the nice feature of D dynamic arrays in terms of bounding checks and "length" property.
> 
> Let's assume:
> 
> extern (C++) interface ICppInterfaceInD {
>    ref const(int[]) indices() const;
> }
> 
> class A: ICppInterfaceInD {
>    private int[] m_indices;
> 
>    extern (C++) ref const(int[]) indices() const {
>      return m_indices;
>    }
> }
> 
> All I want is keeping const correctness like in C++ so no one can modify m_indices and use that as property within const pointer. I thought it may be passed to C++ as some struct of sort:
> 
> struct wrappedArrray(T) {
>    size_t length;
>    T* ptr;
> }
> 
> but it just don't want to be friendly with me.
> 
> How should I rethink the interface with being D-way efficient when using that interface inside of D?

I would recommend using a struct as above or pass the pointer and length separately. Then create a function on the D side that coverts between the struct and a D array.

Note that you cannot use a D array in a C++ interface, it will fail to compile.

-- 
/Jacob Carlborg