Re: [libxml++] node iterators

[Christophe de VIENNE <cdevienne alphacent com>]

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Le Vendredi 23 Mai 2003 18:57, andy glew amd com a écrit :
>
> In other words, I am agreeing with Murray that it is a separate
> class.


Me too (that's what I'm saying in the part of the message you didn't quote :-)

So I started implementing something this way. I have the following classes :
ChildrenList, ChildrenList::iterator and ChildrenList::const_iterator

The API is STL-like :

iterator       ChildrenList::begin();
const_iterator ChildrenList::begin() const;
iterator       ChildrenList::end();
const_iterator ChildrenList::end() const;

on the different iterators we have operators ++(), ++(int), ==(), !=(), *() 
and ->().
I plan to add rbegin() and rend() and ad-hoc iterators.

Node::get_children() returns a reference to a ChildrenList which is an 
attribute of Node initialised in constructor.


One problem I faced is the type return by iterator::operator*().
I first wanted to return a Node &. It is, I think, more logical, and avoid 
writing things like (*iter)->do_something().
However this change the use of dynamic_cast to 'test' the type of node. If the 
cast fail we have an exception instead of just returning a null pointer.

Moreover this will make a bit heavy the switching from a version to another 
(but this may be acceptable from a 1.0 to 2.0 version upgrade).

So the question is :
What do you expect as a return type for 
Node::ChildrenList::iterator::operator*() ?

remark:
One alternative I thought of is to have :
  Node * operator*()
and
  Node * operator->()
So we can both avoid complicating use of dynamic_cast and writing stuffs like 
(*iter)->do_something().
But I don't think this is a very standard behavior and would prefer not to do 
that.




Regards,

Christophe
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