Hamish Mackenzie wrote:
>  Ok I think I understand the problem now.  What does node->document()
>  return and what does it point to???

it returns a dom::document_ptr, which behaves exactly the same way
as the other _ptr types, i.e. it has reference semantics.

>  Well I think as with the node->parent() it should return a proxy
>  object.  Something like...

that's what it does indeed.


>  // non owning reference
>  class document_ref
>  {
>  public:
>    // Define document related methods here
>  protected:
>    document_ref() : raw_( 0 ) {}
>    xmlDoc * raw_;
>  };
>  
>  // non owning pointer
>  class document_ptr
>  {
>  public:
>    document_ptr( document_ref * );
>    document_ref operator *() { return ref_; }
>    document_ref * operator ->() { return &ref_; }
>  private:
>    document_ref ref_;
>  };
>  
>  // owning object with deep copy
>  class document : public document_ref
>  {
>  public:
>    explicit document( const std::string & file );
>    document( document_ref source )
>    {
>      // Deep copy here
>    }
>    ~document() { xmlFreeDoc( raw_ ); }
>  };

I don't really understand why we need three different classes to
manage documents. In particular I don't understand why you provide
a 'document_ptr' that is a wrapper around document_ref.

And I don't use a 'document' class, as that is managed implicitely
by my dom::document_ptr:

dom::document_ptr document; // create new document;
dom::document_ptr doc(document); // create second reference to it
dom::document_ptr doc2 = document.clone(); // clone it, i.e. make deep
                                               copy

>  root->document() can return document_ptr or document_ref.

indeed, that's what it does.

>  
>  
> >>value_types could exist but it would require a deep copy to be
> >>consistent.  If you do want to define it then I suggest
> >
> >you mean if I do *not* want to define it ?
>  
>  
>  Yes, you could
>  1) define a deep copy value_type

that doesn't work as there is no way to copy nodes 'out of the
document'.

>  2) typedef void value_type;
>  3) leave it undefined
>  
>  
> >>Your iterator types look good.  Why is there an extra level of
> >>indirection in basic_element_const_iterator?
> >
> >the const iterator is non-functional right now. I'v been wondering
> >how to provide one. It seems I would need to define a 'const_node_ptr'
> >set of classes.
>  
>  
>  I think that is right.  I would prefer it to be
>  
>  typedef node_pointer< node_ref > node_ptr;
>  typedef node_pointer< const_node_ref > const_node_ptr;
>  
>  In fact you will probably need const_ versions for all your reference,
>  pointer and iterator types. Though the pointers and iterators should
>  just be additional instances of template classes.

yes

Stefan




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