Re: [boost] API Review request: XML API for C++, second round

From: Hamish Mackenzie (hamish_at_[hidden])
Date: 2003-06-26 09:44:43

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

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

// 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_ ); }
};

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

> > 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
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.

-- 
Hamish Mackenzie <hamish_at_[hidden]>