Tom Widmer <tom_usenet@hotmail.com> writes:
On Tue, 02 Mar 2004 09:23:36 -0500, David Abrahams <dave@boost-consulting.com> wrote:
Tom Widmer <tom_usenet@hotmail.com> writes:
If I'm misusing the code, is there some reason for this? It's inconvenient that the default constructor doesn't initialize pointers to some consistent value; the problem goes away when I change the indirect_iterator default constructor:
94c94,96 < indirect_iterator() {} ---
indirect_iterator() : super_t( Iterator() ) {}
That gives you a false sense of safety. Default initializing many iterator types is a no-op - they are still unusable (e.g. std::list::iterator).
or, in the same way, int*.
Default initializing an int* isn't a no-op, and you can equality compare such int*s. The same isn't true for std::list::iterator, which is why I chose it.
e.g. It i = It(); It j = It(); bool b = (i == j);
That's well defined for It=int* (and It=istream_iterator<T>), but UB for It=std::list<int>::iterator (since i and j are singular).
Right; I misread your point. I meant: int* p1; int* p2; bool b = (p1 == p2); // undefined behavior Same thing if we replace the int* by std::list::iterator. I guess std::list::iterator is a bit worse in some sense because of the point you're making. -- Dave Abrahams Boost Consulting www.boost-consulting.com