*&

[danny van elsen]

hello all,

when a function has a '*&' parameter, as in
Gtk::TreeView::get_cursor(Gtk::TreePath&, Gtk::TreeViewColumn*&)

- what could be the reason for designing a function like this?
- how do I use this function? This doesn't work ...

Gtk::TreeModel:ath path;
Gtk::TreeViewColumn column;

....
treeview.get_cursor(path, &column);

error: no matching function for call to
`Gtk::TreeView::get_cursor(Gtk::TreePath&, Gtk::TreeViewColumn*)'
note: candidates are:
void Gtk::TreeView::get_cursor(Gtk::TreePath&, Gtk::TreeViewColumn*&)

bye, Danny.

 

[Rolf Magnus]

hello all,

when a function has a '*&' parameter, as in
Gtk::TreeView::get_cursor(Gtk::TreePath&, Gtk::TreeViewColumn*&)

- what could be the reason for designing a function like this?

That the function wants a pointer to be passed by reference, so that it can
change the pointer that the caller passed.

- how do I use this function? This doesn't work ...

Gtk::TreeModel:ath path;
Gtk::TreeViewColumn column;

...
treeview.get_cursor(path, &column);

This doesn't give an lvalue, i.e the caller can't change the value of
"&column".

Maybe this is what you need:

Gtk::TreeModel:ath path;
Gtk::TreeViewColumn* column;

treeview.get_cursor(path, column);

But it depends on what the function expects and what it does with the
parameter. Consult the documentation of that function.