Re: [boost] [uuid] uuid::create() function

From: Matthias Troyer (troyer_at_[hidden])
Date: 2007-06-12 04:11:28

On Jun 11, 2007, at 8:33 PM, Andy wrote:

> "Jos Hickson" <jos.hickson_at_[hidden]> wrote in
> news:fc03d05a0706060823v59628c64xd1bcda61e9fd5f48_at_[hidden]:
>
>> On 06/06/07, Peter Dimov <pdimov_at_[hidden]> wrote:
>>> Jos Hickson wrote:
>>>> On 05/06/07, Peter Dimov <pdimov_at_[hidden]> wrote:
>>>>> [snip] ... and if Engine
>>>>> is a template parameter, we probably need to support engines that
>>>>> only take a 32 bit seed anyway.
>>>>
>>>> Isn't it the case that the maximum seed size is related (equal?) to
>>>> the difference between the max and min values produced by a
>>>> particular engine and also that all the engines in Boost Random
>>>> provide the iterator version of seed?
>>>
>>> The seed for mt19937 is 624 words.
>> Aah, a bit bigger then!
>
> I have been thinking about this for awhile now, and maybe I should use
> Peter's suggestion and only support random number generators that  
> can be
> seeded with a single number.  And xor with rd_.

Please don't! As mentioned before that would only give 2^32 different  
UUIDs.

The best solution is just to allow any generator producing values of  
a specified type (e.g. unsigned int or unsigned char) to be used with  
create(), and leave the initialization of the generator to the user.

Matthias