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To: Andrea Faulds <ajf@ajf.me>, internals@lists.php.net
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Date: Tue, 31 Jan 2017 14:07:35 +0100
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Subject: Re: Reseeding rand()/mt_rand()
From: cmbecker69@gmx.de ("Christoph M. Becker")

On 30.01.2017 at 17:29, Andrea Faulds wrote:

> Christoph M. Becker wrote:
> 
>> Just a quick idea:
>>
>> <?php
>>
>> class PNRG {
>>     public function __construct($seed = null) {…}
>>     public function get() {…}
>> }
> 
> I've long favoured an API along these lines. One size does not fit all,
> you need two APIs for (non-crytographic) random numbers:
> - automatically-seeded, non-reproducible numbers (a global function like
> rand())
> - manually-seeded, reproducible number sequences (objects)
> 
> Currently we mix these two, and it's a mess. The easy solution would be
> a random number-generating object like you propose, to cover the second
> use-case. We could also introduce a non-manually-seedable global PRNG
> also, if desired. Perhaps as a static method of that class.
> 
> One thought: it'd be nice if you had two different methods, one that
> mutates in places, and one that doesn't, i.e.:
> 
> $prng1 = new PRNG(SEED);
> [$randomNumber, $prng2] = $prng2->getWithNewPRNG();
> 
> v.s.:
> 
> $prng = new PRNG(SEED);
> $randomNumber = $prng->get();
> $randomNumber2 = $prng->get();

Thanks, Andrea!  I like all your suggestions, and I'd be happy to see a
respective RFC – unfortunately, I won't have time to do this myself in
the near future.

-- 
Christoph M. Becker