On Tue, Jun 9, 2009 at 11:57 PM, Dean Michael Berris<mikhailberis@gmail.com> wrote:
On Tue, Jun 9, 2009 at 9:49 PM, Vicente Botet Escriba<vicente.botet@wanadoo.fr> wrote:
Two bloom_filters with different hash functions are not comparable. Don't you think that the hash functions make part of the bloom_filter type?
bloom_filter<M, hash_1, ... hash_k>bf;
Thinking about it a little more, yes this makes sense. However, pending the formalization of variadic templates, I'm leaning towards supporting Fusion sequences in the collection of hash functions:
bloom_filter<Input, M, Sequence> bf;
This way I can deduce K from size<Sequence> and maybe even derive the bloom_filter linearly from the Sequence elements (to optimize the storage, using the compressed_pair trick). I'm still mulling it around in my head, and will be trying to implement this in the morning (PH time).
My only worry with this is that I'd have to define the Concept for hash function types. It shouldn't be too hard especially if I'll build upon the Boost.Hash concepts (if they're applicable).
This has also been addressed in the version that's in revision 53785 of the Boost Sandbox. :-)
If hash functions make part of the bloom_filter type there is no issue. No need to compare the hash functions at run-time. The compiler will do it for you.
Yup, this is true. Now I just have to implement it using Boost.Fusion -- this I'm worried about because this somewhat makes the bloom_filter implementation (and usage) a little more complex than I'd like, but if the requirements dictate it then there would be less reasons for me to avoid it. ;-)
And my worries were misplaced. :-) The implementation seems cleaner now IMO using Boost.Fusion internally. Fusion saves my day again. :-D
If hash functions make part of the bloom_filter type there is no issue, only the data must be serialized.
You're correct here. Now it's just a matter of me implementing it then. :-)
And this is already done too. :-) Thanks for the insights! :-D -- Dean Michael Berris | Software Engineer, Friendster, Inc. blog.cplusplus-soup.com | twitter.com/mikhailberis | linkedin.com/in/mikhailberis | profiles.friendster.com/mikhailberis | deanberris.com