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From: Stefan Monnier <monnier@iro.umontreal.ca>
To: Achim Gratz <Stromeko@nexgo.de>
Cc: emacs-devel@gnu.org
Subject: Re: random doesn't feel very random
Date: Sun, 26 Aug 2012 20:50:22 -0400	[thread overview]
Message-ID: <jwvsjb9mabt.fsf-monnier+emacs@gnu.org> (raw)
In-Reply-To: <87wr0livd4.fsf@Rainer.invalid> (Achim Gratz's message of "Sun, 26 Aug 2012 16:24:55 +0200")

> Therefore the PRNG should be seeded once at start-up, from a good
> source of entropy.

I tend to agree.

> Given the widespread use of (random t) it should probably be made a
> no-op and a separate API to provide a local state for application that
> wish to control it for whatever reason should be made available.

IIRC Emacs fails to seed its PRNG at start (IOW it is seeded with
a constant), which is why many packages use (random t).

So I think the right thing to do now is to do seed it at startup, then
make (random t) a no-op.

We could consider adding a way to get the PRNG state and reset it later,
but since the PRNG state is Emacs-wide and Emacs is more like an OS than
like an application w.r.t its packages, such an interface would need to
allow several named PRNGs, so you'd call (random N <id>) to get the next
"random" number from <id>'s stream.


        Stefan



  parent reply	other threads:[~2012-08-27  0:50 UTC|newest]

Thread overview: 43+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-08-24  5:47 random doesn't feel very random Ivan Kanis
2012-08-24  6:22 ` Tassilo Horn
2012-08-24 17:19   ` random doesn't feel very random, random doesn't feel very random, " Ivan Kanis
2012-08-24 18:50     ` Stephen J. Turnbull
2012-08-25  7:46       ` Ivan Kanis
2012-08-24  6:30 ` Leo
2012-08-24 22:48   ` Richard Stallman
2012-08-24 22:57     ` Andreas Schwab
2012-08-25 20:55       ` Richard Stallman
2012-08-25 23:25         ` Leo
2012-08-26 13:12           ` Richard Stallman
2012-08-26 14:24             ` Achim Gratz
2012-08-26 23:22               ` Leo
2012-08-27  0:50               ` Stefan Monnier [this message]
2012-08-27  6:31                 ` Simon Leinen
2012-08-27  3:41               ` Richard Stallman
2012-08-27  4:48                 ` Stefan Monnier
2012-08-31  9:41                   ` Eli Zaretskii
2012-08-31 15:06                     ` Stefan Monnier
2012-08-31 15:23                       ` chad
2012-08-31 17:50                       ` Eli Zaretskii
2012-08-31 19:43                         ` Stefan Monnier
2012-09-01  1:18                           ` Paul Eggert
2012-09-01  7:19                             ` Achim Gratz
2012-09-01 13:19                               ` Paul Eggert
2012-09-04 19:19                                 ` Nix
2012-09-04 20:07                                   ` Paul Eggert
2012-09-04 20:11                                     ` Nix
2012-09-02 12:27                               ` Jason Rumney
2012-09-02 13:08                                 ` Stefan Monnier
2012-09-01  7:22                             ` Ivan Kanis
2012-09-01 11:13                             ` joakim
2012-08-31 23:04                       ` Leo
2012-08-27  5:17                 ` Achim Gratz
2012-08-31  9:42                   ` Eli Zaretskii
2012-08-31 15:07                     ` Stefan Monnier
2012-08-31 17:50                       ` Eli Zaretskii
2012-08-26  9:06         ` Ivan Kanis
2012-08-24  7:03 ` Stephen J. Turnbull
2012-08-24  9:10   ` Paul Eggert
2012-08-24 17:45     ` Stephen J. Turnbull
2012-08-24 12:45 ` OT: appropriateness of "random" for playlist generation (was: random doesn't feel very random) Jeremiah Dodds
2012-08-24 14:37 ` random doesn't feel very random Drew Adams

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