Hi everyone,
I have encountered a problem compiling template classes using gcc
version 4.0.3. The code compiles and works fine under Visual Studio
8.0.
Below is a sample of the code that causes the issues. The
AVLTree::begin () function returns an Iterator by value. This Iterator
is created automatically by calling the constructor
"Iterator::Iterator (item_type* node_ptr);" below when I return the
item_type* pointer. Then, I would like to pass this newly created
object by reference by calling the "Iterator::Iterator <item_type>&
operator=(Iterator <item_type>& iter);" function. However, it seems
that gcc cannot pass the newly created Iterator object as reference.
At first I thought that I should overload the & operator for the
Iterator class but it didn't help.
I think the problem could be resolved by passing the Iterator from
AVLTree::begin () by reference (although I haven't tried) but in that
case I would have to worry about allocating/deallocating memory and
this would make my code less robust. Is there any way to tell the
compiler how to automatically convert
Iterator<item_type>
to
Iterator<item_type>&
with item_type
AVLTree<std::basic_string<char, std::char_traits<char>,
std::allocator<char> >, Task*>
?
The error message:
../../core/Task.cpp: In member function `virtual void
Task::visitor_update_task_avltree(TASK_AVLTREE*)':
../../core/Task.cpp:1787: error: no match for `operator=' in
`task_iter = AVLTree<key_type, item_type>::begin() [with key_type =
std::basic_string<char, std::char_traits<char>, std::allocator<char>
, item_type = Task*]()'
../../core/../datastructures/Iterator.cpp:104: note: candidates are:
Iterator<item_type>&
Iterator<item_type>::operator=(Iterator<item_type>&) [with item_type =
AVLTreeNode<std::basic_string<char, std::char_traits<char>,
std::allocator<char> >, Task*>]
../../core/../datastructures/Iterator.cpp:111: note:
Iterator<item_type>&
Iterator<item_type>::operator=(Const_Iterator<item_type>&) [with
item_type = AVLTreeNode<std::basic_string<char,
std::char_traits<char>, std::allocator<char> >, Task*>]
Code:
template <class item_type>
class Iterator
{
public:
Iterator () {};
Iterator (item_type* node_ptr);
Iterator (Iterator <item_type>& iter);
...
Iterator <item_type>& operator=(Iterator <item_type>& iter);
Iterator <item_type>& operator=(Const_Iterator <item_type>& iter);
...
Iterator <item_type>& operator& ();
...
};
template <class key_type, class item_type>
class AVLTree
{
AVLTree ();
...
Iterator <AVLTreeNode <key_type, item_type> > begin ();
...
};
void Task::visitor_update_task_avltree (TASK_AVLTREE* task_avltree)
throw (Exception)
{
TASK_AVLTREE::iterator task_iter;
for (task_iter = task_avltree -> begin (); task_iter != task_avltree
-> end (); ++task_iter)
{
...
}
}
Thanks,
Gabe
