On 05/26/2010 09:37 AM, Michel Fortin wrote:
On 2010-05-25 18:27:32 -0400, Andrei Alexandrescu
<[email protected]> said:
There are a bunch of "soft" primitives. Those are meant to put a stop
to the iterator invalidation problems experienced in the STL. The
container implementor may alias softXyz to xyz if she knows the
operation won't mess the ranges currently iterating the container
(which is the case for most node-based containers). I haven't yet
discussed subtler cases in which a range starts with a removed element
etc., but I plan to.
Looks good, but I think something is missing. While I agree with the
idea of having distinguishable "soft" operations, to pass it to other
functions you should be able to make a "soft" shell around your
container and pass that shell mapping non-soft functions to soft ones,
ensuring only soft functions can be called. It could look like this:
insertAtRandomPlace(myContainer.soft, element);
Now you know insertAtRandom won't and *can't* invalidate your
iterators/ranges, and you don't need to write a separate
"softInsertAtRandom" that only calls soft functions.
Initially I thought containers that naturally support soft (well,
"stable" since 5 minutes ago) operations would simply alias the
non-stable versions and the stable versions to the same call.
But now you got me thinking that a container might want to take
advantage of both to implement slightly different approaches. I haven't
met such a container yet, but that doesn't mean they aren't possible.
Andrei
