[armedbear-devel] Fixing PRINT.RANDOM-STATE.1

[Theam Yong Chew]

On 16-Jul-2011 5:00 AM, "Erik Huelsmann" <ehuels at gmail.com> wrote:
>
>
> Today I was looking at fixing some of our PRINT.* failures in the ansi test suite.
>
> Hoping to get an easy start, I started looking PRINT.RANDOM-STATE.1

...

> there's no way to extract a 'seed' value from the object to be used
> to initialize an object into the same state.
>
> So, I'm now pondering what action to take. I'm seeing several options:
>
> 1. build our own pseudo random number generator with its own random state
> 2. serialize the Random object to a byte array and use that array as
> some sort of printed representation (sure, we'll definitely need to
> look into ways to load)
>
> The advantage of (1) is that we can create it all in Lisp, however,
> it's pure additional code, since we won't be leveraging what's
> already there.

You are talking about leveraging Java, but what about leveraging Lisp?
I'm not sure about speed, but this is often cited on the
web/newsgroups,

http://www.ccs.neu.edu/home/dorai/notes/mrg32k3a.lisp

and there're the ones from SBCL too.

> The advantage of (2) is that we can use what Java maintains for us
> and even better: we can use the random number generator shared
> between Lisp and Java code. I imagine the disadvantage of this
> solution is that the serialization of the random state can differ
> between Java versions and implementations.




I would tend to favour Lisp solutions, but yeah...

Yong.