Thorsten Ottosen wrote:
"Daniel James" <daniel@calamity.org.uk> wrote in message news:d0mtqf$98h$1@sea.gmane.org...
Peter Dimov wrote:
It is a deliberate design decision that the algorithms are fully specified. The goal is precisely to not allow you (as an implementor) to change them.. ;-)
Of course the fact that hash_range gives the same result as hash_value on the corresponding container is no accident, either.
Yes, the reason that this came up, is because this wasn't true for Jeremy's original implementation. But I think his hash function for strings was faster, which might be desirable.
Peter, I don't like that hasing a string is suboptimal. Likewise, I would like hasing of sub_range<string> or sub_range<vector<char>> to be really fast.
See my other post. When talking about hash functions, you really need to have a clear understanding of "suboptimal" in mind. I don't claim to be an expert, but at least I have tried to familiarize myself with the research done in this area. My advice is: if you are going to mess with a (standard) hash function, you better (a) understand what you are doing, (b) have an extensive test suite that benchmarks an unordered_map with a wide range of real-world key sets.