[Newbies] Randomness
michael rice
nowgate at yahoo.com
Thu Apr 7 12:20:54 UTC 2011
And I can acquire the new behavior by updating Squeak?
Michael
--- On Thu, 4/7/11, Bert Freudenberg <bert at freudenbergs.de> wrote:
From: Bert Freudenberg <bert at freudenbergs.de>
Subject: Re: [Newbies] Randomness
To: "A friendly place to get answers to even the most basic questions about Squeak." <beginners at lists.squeakfoundation.org>
Date: Thursday, April 7, 2011, 6:19 AM
The new behavior is that you get a different stream of random numbers each time you start the image. Or at least it's really really unlikely you get the same sequence again.
- Bert -
On 07.04.2011, at 02:54, michael rice wrote:
So it was a problem? The old behavior was: if I saved a project and quit the image without saving it, the next time I bought up the image and loaded the project I would get the same stream of random numbers. What is the new behavior?
Michael
--- On Wed, 4/6/11, David T. Lewis <lewis at mail.msen.com> wrote:
From: David T. Lewis <lewis at mail.msen.com>
Subject: Re: [Newbies] Randomness
To: "A friendly place to get answers to even the most basic questions about Squeak." <beginners at lists.squeakfoundation.org>
Date: Wednesday, April 6, 2011, 8:35 PM
I made the update in Squeak trunk similar to the Etoys image, but used
the existing seed generator in Random>>initialize on the
theory that if
the generator is good enough for a new Random, it should be good enough
for an existing one too ;)
Michael, thanks for spotting the problem.
Dave
On Tue, Apr 05, 2011 at 01:16:31PM +0200, Bert Freudenberg wrote:
>
> On 05.04.2011, at 02:32, Levente Uzonyi wrote:
>
> > On Mon, 4 Apr 2011, michael rice wrote:
> >
> >> I forgot to mention, I'm using the random number tile and scripting. Does that make it more difficult?
> >
> > Not really, RandomNumberTile uses the global random number generator of Collection. I don't know how/why is it serialized/restored
>
> It is not stored in the project. But in trunk, the seed does not get re-initialized when starting up. In the Etoys image, Collection class has a startUp method
>
> startUp
> RandomForPicking seed: Time totalSeconds hash asFloat.
>
> IMHO we should adopt something like this for trunk (maybe with your "more" random approach below).
>
> - Bert -
>
> > but here's a method which should help:
> >
> > RandomNumberTile >> #comeFullyUpOnReload: smartRefStream
> >
> > | seed |
> > [
> > seed := (Time millisecondClockValue bitAnd: 16r3FFFFFFF) bitXor: self hash.
> > seed := seed bitXor: (Time totalSeconds bitAnd: 16r3FFFFFFF).
> > seed := seed bitXor: 16r3FFFFFFF atRandom.
> > seed = 0 ] whileTrue. "Try again if ever get a seed = 0"
> > Collection mutexForPicking critical: [
> > Collection randomForPicking
seed: seed ].
> > ^super comeFullyUpOnReload: smartRefStream
> >
> > It's drawback is that it will reseed the rng for every RandomNumberTile. The best solution would be if Etoys would use a custom Random instance or a subclass where this is done by default.
> >
> >
> > Levente
> >
> >>
> >> Michael
> >>
> >> --- On Mon, 4/4/11, Levente Uzonyi <leves at elte.hu> wrote:
> >>
> >> From: Levente Uzonyi <leves at elte.hu>
> >> Subject: Re: [Newbies] Randomness
> >> To: "A friendly place to get answers to even the most basic questions about Squeak." <beginners at lists.squeakfoundation.org>
> >> Date: Monday, April 4, 2011, 8:08 PM
> >>
> >> On Mon, 4 Apr 2011, michael rice wrote:
> >>
> >>> I just noticed that when I load a morphic project I get the same stream of random numbers each time. Is there a simple way to install a new different random seed each time the project is loaded?
> >>
> >> If you serialize the Random object, then it will have the same state when it's restored. I guess you should create a subclass of Random, which implements #comeFullyUpOnReload:. That method can reinitialize the seed of the random number generator. You may want to check UUIDGenerator >> #makeSeed if you don't know how to get a good seed for your rng.
> >>
> >>
> >> Levente
>
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