Re: [Boost-users] seeking comments on 'weak_key_map' experiments

Is there some way that this can interface with boost::shared_ptr/weak_ptr better? weak_key_map m; boost::shared_ptr<int> k(new int(1)); m.insert(std::make_pair(k,5));

assert(*m.find(k) == 5);

k.reset();

assert(m.empty());

I'd also like that, but in this approach, I can't figure how to hook into the key shared_ptr deleter to have access to a notification of the smart_ptr deletion. I think we can currently get the current deleter of a shared_ptr, but we can't change it to combine it with another deleter. I rather suspect that the data structure would need to be implemented from

scratch. One of the nastier problems is how to deal with the case of: iterator invalidation. The safest solution is to make the presence of an iterator to a particular element guarantee that the key continues to exist.

That's a good point ! To make a parallel with Python, the iteration seems to be an issue : quote from Python doc *Note: Caution: Because a WeakValueDictionary is built on top of a Python dictionary, it must not change size when iterating over it. This can be difficult to ensure for a WeakValueDictionary because actions performed by the program during iteration may cause items in the dictionary to vanish "by magic" (as a side effect of garbage collection). * Reimplementing the whole map structure brings the task to another level of complexity...