From: David Abrahams (dave_at_[hidden])
Date: 2004-01-04 08:26:18
"Wyss, Felix" <FelixW_at_[hidden]> writes:
>> > I think it would be better to mandate that resize()
>> > 1) guarantees iterators remain valid
> [Wyss, Felix] I would argue that resize() is semantically an invariant
> operation on a hash table; it doesn't modify the content.
> It's an operation to adjust the memory consumption and lookup
> performance tradeoff at runtime.
Just like std::vector<T>::reserve? Should that guarantee that
iterators remain valid and not throw exceptions?
> As a previous poster pointed out,
> the SGI implementation guarantees that iterators remain valid.
>> > 2) provides the strong exception guarantee
> [Wyss, Felix] Same here, resize() is a semantically invariant operation.
I don't see why that should have any bearing.
> It's easy to implement a hash table that provides the strong exception
> guarantee for resize() by caching the hash code.
> This even increases performance for types with expensive compares.
> I thus dare asking: Why not?
It incurs a space cost that some people may not want to pay and
decreases performance for some types.
-- Dave Abrahams Boost Consulting www.boost-consulting.com
Boost list run by bdawes at acm.org, gregod at cs.rpi.edu, cpdaniel at pacbell.net, john at johnmaddock.co.uk