Hi Andrea, On Mon, Jan 12, 2015 at 9:05 AM, Andrea Faulds <a...@ajf.me> wrote:
> > On 11 Jan 2015, at 23:56, Jordi Boggiano <j.boggi...@seld.be> wrote: > > > > On 11/01/2015 22:12, Andrea Faulds wrote: > >> * Make mt_srand() and srand() do nothing and produce a deprecation > notice > > > > That is the only point with which I disagree. Looking at > http://3v4l.org/FLHBV we see that while indeed across PHP versions the > result has not always been the same, it generally is, and especially within > one given version setting a seed means you get predictable results. > > > > This has benefits in some cases like fixtures generation where it might > not be important if the output changes when you upgrade PHP, but you don't > want entirely different fixtures every single time. Obviously if we could > guarantee the algo won't change it would be even better. > > > > Bottom line is I think it's important to have the ability to set the > seed yourself. > > > > > On 11 Jan 2015, at 23:57, Yasuo Ohgaki <yohg...@ohgaki.net> wrote: > > > > However, I object removal of srand. > > Game programmers need "the same random sequence" on occasion. > > There should be srand to get the same sequence for repeatable behaviors. > > > > rand()/srand() may be renamed to sys_rand()/sys_srand() (or whatever > > suitable name for them) in case user needs system random sequence > > for whatever reasons. I don't insist to keep system's rand/srand, though. > > I don’t disagree with having some mechanism for predictable random number > generation from a seed, but I think the global random number generator is > the wrong place to do it. It’s not guaranteed to be predictable, and > everything uses it, so some library you’re using might advance it without > you realising. > > Much better would be to add a new, OOP API that gives you your own number > generator (no global state) and requires explicitly specifying the > algorithm (cross-version compatibility), with a guarantee that it won’t > break in new PHP versions. > > Something like this, maybe: > > $numgen = new RandomNumberGenerator(RAND_MERSENNE_TWISTER, time()); // > could auto-seed with time() > $randInt1 = $numgen->getInt(0, 100); // gets random integer and > advances this generator > list($randInt2, $numgen) = $numgen->newGetInt(0, 100); // gets random > integer and returns a new, advanced generator > $serialised = $numgen->serialiseState(); // Or maybe > $numgen->getSeed() ? > > Does that work? It works, but I prefer to have procedural API also (and OO API if it is needed.) I like multi paradigm programming language. Pseudo random number generator is pseudo. We are better off with real random generator when cryptographic random number is needed. So renaming mt_rand() -> rand() / rand() -> sys_rand() and keeping mt_rand() alias would be enough. IMO. BTW, difference between 32bit and 64bit platforms would not be a problem as long as it is documented. Regards, -- Yasuo Ohgaki yohg...@ohgaki.net
