[Boost-announce] [review results] hash functions accepted

From: Thorsten Ottosen (nesotto_at_[hidden])
Date: 2005-03-21 10:48:19

Dear all,

I'm pleased to announce that Daniel James' hash-functions library
is accepted into boost. The review comments were generally positive,
a few bugs were fixed and in general we had a solid
discussion in favor of the current design.

Congratulations to James!

I would like to thank all who partcipated:

Dave Harris
Peter Dimov
John Maddock
Joaquin M.
Chris Jefferson
Caleb Epstein
Topher Cooper
David Abrahams
Alberto Barbati
Tobias Swinger
Jaap Suter
Rob Stewart
Bronek Kozicki

Below is a list of issue that was resolved; let us have a discussion
about any of them if I have misunderstood something. Also, feel free
to mention something if it was forgotten by me.

Issues and solutions:
---------------------

1. for those who don't want to include the whole std-lib, individual  headers
    can be put in hash/std/XX.hpp (but see 3)

2. update docs to reflect that ADL is used.

3. consider if the primary template should not take 1 range parameter and call 
hash_range;
    unordered containers can then be explicitly overloaded when they become 
available.
    this would also have the great effect that subranges like 
sub_range<string> "just works"
    by default

4. avoid too many zero hash values by defaulting to something other than 0

5. change implementation of hash values for pointers so undefined behavior is 
gone (and consider adding  x + (x >> 3) )

6. the design aim was predictibility and to minimize collision; for the latter 
part, I
    would like to know if similar values hash to similar buckets or not. If 
very different
    objects end up in the same buskets, wouldn't equality be much faster 
rejected?
    Should this be a concern?

7. the hash_ptr<> suggestion is better done with general indirected function

8. hash_range should be overloaded to take an initial seed

best regards

Thorsten, review manager

-- 
Thorsten Ottosen
----------------------------
www.dezide.com
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www.open-std.org/JTC1/SC22/WG21/