D - more or less power than C++?

Sat Mar 4 00:13:19 PST 2006

Here is the real life example:

This is C++ wrapper of  DOM element
from my HTMLayout SDK:

It wraps HELEMENT which is in fact reference counted
handler of HTML DOM object.

namespace dom
{
    class element
    {
    protected:
      HELEMENT he;

      void use(HELEMENT h) { he = (HTMLayout_UseElement(h) == HLDOM_OK)? h: 
0; }
      void unuse() { if(he) HTMLayout_UnuseElement(he); he = 0; }
      void set(HELEMENT h) { unuse(); use(h); }

    public:

      element(): he(0) { }
      element(HELEMENT h)    { use(h); }
      element(const element& e) { use(e.he); }
      operator HELEMENT() const { return he; }
      ~element()                { unuse(); }

      element& operator = (HELEMENT h) { set(h); return *this; }
      element& operator = (const element& e) { set(e.he); return *this; }

     ....
  }
}

Usage of this in C++ (code of DOM element event handler, aka "behavior"):

virtual BOOL on_mouse(HELEMENT he, HELEMENT target,
     UINT event_type, POINT pt, UINT mouseButtons, UINT keyboardStates )
    {
        dom::element el = he;
            // 'use' handler - add_ref it to prevent from deletion
        if(!el.is_valid())
             return false;

       dom::element root = el.root(); // get root element (<html>)
       dom::element editbox = root.find_first("input[type='text']");
           // get first edit box using CSS selector
       editbox.text("Hello world!"); // set text to it
       .....
    }

As you may see it is mission critical here to have ctor/dtors/assignment in 
structs.
It is simply not feasible (realisticly) to call manually each time use/unuse 
methods for all objects
in the function. Dead corner.

I really don't know how to design lightweight wrapper for HTMLayout for D. 
<g>

Any real advices?

Andrew.