On Wed, May 12, 2021 at 6:43 PM Christian Schneider <cschn...@cschneid.com>
wrote:
> Am 11.05.2021 um 23:20 schrieb Larry Garfield <la...@garfieldtech.com>:
> > 3) Perhaps it should be named RandomSequence or similar? It's not truly
> generating random numbers. It's generating a repeatable but difficult to
> produce sequence off of a seed value. That's not the same thing as
> random_int() et al.
> >
> > So, at first pass, an API could be as simple as (pseudocode):
> >
> > class RandomSequence {
> > public function __construct(int $seed = time(), $algorithm =
> 'some_default') { ... }
> >
> > public function next(): int { ... }
> > }
> >
> > And that's it. That's nice and simple and predictable to use.
>
>
> Would the generated values fill the whole int range, i.e. 64 bit on modern
> systems?
>
> And would it make sense to add max and min for the generated values like
> we have with random_int()?
> Because mapping arbitrary int values to a specific range is error-prone:
> Just using modulo leads to bias in the resulting values.
>
>
What I initially proposed is an interface something like:
interface RandomSource {
public function next($length): string;
}
where the string returned would be of the specified length and made up of
random bytes.
I understood that internally, an 32/64 bit int is equivalent to 4 or 8
bytes and that various internal implementations already use ints and not
bytes to provide other constructs like shuffle() and array_rand() with
random behavior.
So I can understand if the function would return an int or an array of
ints. Maybe you can contradict me if I understood this wrong.
But to fulfill all the need for random, one can further use a wrapper class
that can be called RandomGenerator that takes a RandomSource as parameter
and have all types of handy methods:
generateInt($min = 0, $max = PHP_INT_MAX)
generateBoolean()
generateNumber() // float between 0 and 1
generateString($length, $characters = '')
RandomGenerator would take care of the uniform distribution of values
generated based on uniform distribution of source bytes/ints generated.
I think that keeping a simple way to generate random information is
important so that it can easily be reimplemented in various ways when
needed.
I like the byte approach more because generateString(4, 'abcd') could
consume only 1 byte from the random source.
Of course, in this picture, RandomSource implementations can be
serializable, if it makes sense.
BTW, this name proposal is inspired from this library:
https://github.com/paragonie/RandomLib as I'm not good with namings either.
Alex
