Convinience class for safe disconnection. Iterators must not be used beyond the lifetime of the list they work on. A connection object can be created from a slot list iterator and may safely be used to disconnect the referred slot at any time (disconnect()). If the slot has already been destroyed, disconnect() does nothing. empty() or operator bool() can be used to test whether the connection is still active. The connection can be blocked (block(), unblock()).
This is possible because the connection object gets notified when the referred slot dies (notify()).