Re: [boost] unordered_map 32bit VS 64bit

Subject: Re: [boost] unordered_map 32bit VS 64bit
From: Andrey Semashev (andrey.semashev_at_[hidden])
Date: 2012-01-26 07:46:56

On Thu, Jan 26, 2012 at 3:29 PM, Daniel James <dnljms_at_[hidden]> wrote:
> On 26 January 2012 11:16, Andrey Semashev <andrey.semashev_at_[hidden]> wrote:
>> On Thu, Jan 26, 2012 at 12:16 PM, Daniel James <dnljms_at_[hidden]> wrote:
>>>
>>> Actually functional/hash doesn't. It's good enough for the standard,
>>> but no better. For numbers that fit into the hash value, it just
>>> returns them unchanged which is fine for a prime number of buckets but
>>> not for power of 2 containers.
>>
>> Well, we probably better fix functional/hash then?
>
> No, it's deliberate. It meets the standard's requirements. No more, no less.

I don't see why it shouldn't do better than required by the standard.
It's quite normal for Boost components to extend the standard and
provide superior solutions.

Anyway, if existing functional/hash functions are not suitable for the
task, we can add the bit mixing wrapper and recommend its usage with
Boost.Unordered.