Re: [boost] [optional] operator<(optional<T>, T) -- is it wrong?

Subject: Re: [boost] [optional] operator<(optional<T>, T) -- is it wrong?
From: Olaf van der Spek (ml_at_[hidden])
Date: 2014-12-01 13:48:25

On Mon, Dec 1, 2014 at 7:45 PM, Gottlob Frege <gottlobfrege_at_[hidden]> wrote:
> On Sun, Nov 30, 2014 at 6:20 PM, Gavin Lambert <gavinl_at_[hidden]> wrote:
>> On 29/11/2014 08:01, Gottlob Frege wrote:
>>>
>>> There are still reasons to use std::map over unordered_map.  Lack of a
>>> cryptographically safe hash is one of them.  There are others (that
>>> I've forgotten, but I've asked the same question to committee members
>>> before, and there were a few reasons that sounded valid to me.)
>>
>>
>> Why should the lack of a cryptographically safe hash matter when you are not
>> doing cryptography?
>>
>> It doesn't really matter what hash is used in internal data structures.
>> (Although obviously there are desirable properties such as having uniform
>> spread to minimise bucket collisions and improve lookup speed.)
>>
>
> Denial of Service attack - I carefully force the input data such that
> the hashes collide and you get worse-case hash-table performance.
> This is a real attack.  Python and a few other languages have already
> fixed their hashes, we have not.

True, but maps suffer from the same problem don't they?
Is a fix even available for maps?

-- 
Olaf