Re: GCC 4.0 Ada.Containers Cursor danger.

[Matthew Heaney <matthewjheaney@earthlink.net>]

"Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de> writes:

> Right, and what should "Replace" mean for a hashed set? Is it
> Remove/Insert? Which influence does it have on iterations?

There is some debate about the exact semantics of Replace.  If you don't
change the equivalence class of the key, then Replace simply replaces
the key/element with a new value.  

The current AI-302 draft does allow you to change the equivalence class
of the key (semantics I don't like), in which case the element is
reinserted at a different position, not unlike a Delete followed by an
Insert (the difference is that Replace can reuse the same memory).  The
equivalence class of the key is what determines its relative order.

So if the equivalence class stays the same, then the order of elements
as returned during iteration won't change.  If the equivalence class
changes, then the order of elements during iteration will change (one
element will have moved to another position).