generic refcounted object perl binding

[YangXi <jiandingzhe msn com>]

Hi, everyone!

I'm asking a question about how to wrapping a refcounted class inside perl. I ask the question here because Gtk is such kind of system.

I have some experience on embedding perl in C++, but have little knowledge on perl XS, and I found perldoc perlxs really puzzled.

Firstly, I have an simple refcounted C++ base class like this:

class Referenced {

public:

    Referenced():refcnt(0) { }

    virtual ~Referenced() {}

    void refInc() { refcnt++; }

    void refDec() {

        if (--refcnt<=0) delete this;

    }

protected:

    int refcnt;

};

In my wrapper, I want to have following functions:

- able to construct my object within perl, like My::Class->new();

- able to construct my object in C++, and pass it to perl sub as argument;

- handle ref count correctly;

So, is these things correct for my XS:

Referenced::new(class)

    PREINIT:

        const char* class;

        Referenced* obj;

        SV* obj_wrap;

        SV* sv;

    CODE:

        // create object

        obj = new Referenced;

        obj->refInc();

        

        // store pointer as unsigned int?

        obj_wrap = newSV(0);

       &nb sp;sv_setuv(obj_wrap, (uv)obj);

        // we always wrap 2 layers SVs for a class? Should I do these things manually?

        sv = newSVrv(obj_wrap, class);

        RETVAL = sv;

    OUTPUT:

        RETVAL

// is this correct?

// I don't really understand when would Perl do automatic scalar conversion, and when should I manually do that.

Referenced::DESTROY(self)

    PREINIT:

        Referenced* self;

    CODE:

        self->refDec();