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Installing Scipy and PyNIO on a Bare Cluster with the Intel Compiler

2 years ago I had the task of running a python-program using scipy on our university cluster, using the Intel Compiler. I needed all those (as well as PyNIO and some other stuff) for running TM5 with the python shell on the HC3 of KIT.

This proved to be quite a bit more challenging than I had expected - but it was very interesting, too (and there I learned the basics of GNU autotools which still help me a lot).

But no one should have to go to the same effort with as little guidance as I had, so I decided to publish the script and the patches I created for installing everything we needed.1

The script worked 2 years ago, so you might have to fix some bits. I won’t promise that this contains everything you need to run the script - or that it won’t be broken when you install it. Actually I won’t promise anything at all, except that if the stuff here had been available 2 years ago, that could have saved me about 2 months of time (each of the patches here required quite some tracking of problems, experimenting and fixing, until it provided basic functionality - but actually I enjoyed doing that - I learned a lot - I just don’t want to be forced to do it again). Still, this stuff contains quite some hacks - even a few ugly ones. But it worked.

Installing GNU Guix 0.6, easily

Org-Source (for editing)

PDF (for printing)

“Got a power-outage while updating?
No problem: Everything still works”

GNU Guix is the new functional package manager from the GNU Project which complements the Nix-Store with a nice Guile Scheme based package definition format.

What sold it to me was “Got a power-outage while updating? No problem: Everything still works” from the Guix talk of Ludovico at the GNU Hacker Meeting 2013. My son once found the on-off-button of our power-connector while I was updating my Gentoo box. It took me 3 evenings to get it completely functional again. This would not have happened with Guix.

Update (2014-05-17): Thanks to zerwas from IRC @ freenode for the patch to guix 0.6 and nice cleanup!

Intro

Installation of GNU Guix is straightforward, except if you follow the docs, but it’s not as if we’re not used to that from other GNU utilities, which often terribly short-sell their quality with overly general documentation ☺

So I want to provide a short guide how to setup and run GNU Guix with ease. My system natively runs Gentoo, My system natively runs Gentoo, so some details might vary for you. If you use Gentoo, you can simply copy the commands here into the shell, but better copy them to a text-file first to ensure that I do not try to trick you into doing evil things with the root access you need.

In short: This guide provides the First Contact and Black Triangle for GNU Guix.

Communicating your project: honest marketing for free software projects

Communicating your project is an essential step for getting the users you want. Here I summarize my experience from working on several different projects including KDE (where I learned the basics of PR - yay, sebas!), the Hurd (where I could really make a difference by improving the frontpage and writing the Month of the Hurd), Mercurial (where I practiced the minimally invasive PR) and 1d6 (my own free RPG where I see how much harder it is to do PR, if the project to communicate is your own).

Since voicing the claim that marketing is important often leads to discussions with people who hate marketing of any kind, I added an appendix with an example which illustrates nicely what happens when you don’t do any PR - and what happens if you do PR of the wrong kind.

If you’re pressed for time and want the really short form, just jump to the questionnaire.

Use the source, Luke! — Emacs org-mode beamer export with images in figure

I just needed to tweak my Emacs org-mode to beamer-latex export to embed images into a figure environment (not wrapfigure!). After lots of googling and documentation reading I decided to bite the bullet and just read the source. Which proved to be much easier than I had expected.

This tutorial requires at least org-mode 8.0 (before that you had to use hacks to get figure without a caption). It is only tested for org-mode 8.0.2: The code you see when you read the source might look different in other versions.

default answer to “I want to connect with you on [hip unfree service]”

I just decided to give a default answer when I get some email from people asking me to connect to them on some new unfree service:

Hello [Person],

You asked me to connect with you on some unfree service. If you still want that, just use a status.net-server. Those are federated, so you can use a number of different providers and still be connected to everyone on any other server.

Surprising behaviour of Fortran (90/95)

1 Introduction

I recently started really learning Fortran (as opposed to just dabbling with existing code until it did what I wanted it to).

Here I document the surprises I found along the way.

If you want a quick start into Fortran, I’d suggest to begin with the tutorial Writing a commandline tool in Fortran and then to come back here to get the corner cases right.

As reference: I come from Python, C++ and Lisp, and I actually started to like Fortran while learning it. So the horror-stories I heard while studying were mostly proven wrong. I uploaded the complete code as base60.f90.

timezones of tccon stations

Timezones of most active TCCON stations in UTC+x (without daylight saving time (DST). Because I needed it and could not find a simple list quickly.

anmyondo: +9,
ascension: 0,
bialystok: +1,
bremen: +1,
caltech: -8,
darwin: 9, # Timezones2008 says 9 1/2???

Equal-Area Map Projections with Basemap and matplotlib/pylab

PDF (read as slides)

Org (reproduce)

Plotting global equal area maps with python, matplotlib/pylab and Basemap.

Table of Contents

information-disbalance creates a power-disbalance

→ a comment to You call it privacy invasion, I don't from Flameeyes.

What you state is a strong version of the “I’ve got nothing to hide” argument. If you’re interested in a thorough debunking, there is a very good article in the chronicle about that: Why Privacy Matters even if you have nothing to hide.

Thank you for your Flattr’s! | Danke für eure Flattr! | Dankon por vian Flattrn!

It’s always a great feeling to see a flattr - Thank you for your support!
You can find new free works for you enjoyment on draketo.de (infrequent and bursty) and 1w6.org (currently weekly but mostly in German).

ArneBab on Flattr

Es ist ein tolles Gefühl, geflattrd zu werden - Danke für eure Unterstützung!

Basic usecases for DVCS: Workflow Failures

If you came here searching for a way to set the username in Mercurial: just run hg config --edit and add
    [ui]
    username = YOURNAME <EMAIL>
to the file which gets opened. If you have a very old version of Mercurial (<3.0), open $HOME/.hgrc manually.

Update (2015-02-05): For the Git breakage there is now a partial solution in Git v2.3.0: You can push into a checked out branch when you prepare the target repo via git config receive.denyCurrentBranch updateInstead, but only if nothing was changed there. This does not fully address the workflow breakage (the success of the operation is still state-dependent), but at least it makes it work. With Git providing a partial solution for the breakage I reported and Mercurial providing a full solution since 2014-05-01, I call this blog post a success. Thank you Git and Mercurial devs!

Update (2014-05-01): The Mercurial breakage is fixed in Mercurial 3.0: When you commit without username it now says “Abort: no username supplied (use "hg config --edit" to set your username)”. The editor shows a template with a commented-out field for the username. Just put your name and email after the pre-filled username = and save the file. The Git breakage still exists.

Update (2013-04-18): In #mercurial @ irc.freenode.net there were discussions yesterday for improving the help output if you do not have your username setup, yet.

1 Intro

I recently tried contributing to a new project again, and I was quite surprised which hurdles can be in your way, when you did not setup your environment, yet.

So I decided to put together a small test for the basic workflow: Cloning a project, doing and testing a change and pushing it back.

I did that for Git and Mercurial, because both break at different points.

I’ll express the basic usecase in Subversion:

  • svn checkout [project]
  • (hack, test, repeat)
  • (request commit rights)
  • svn commit -m "added X"

You can also replace the request for commit rights with creating a patch and sending it to a mailing list. But let’s take the easiest case of a new contributor who is directly welcomed into the project as trusted committer.

dvcs-basic-svn.png

A slightly more advanced workflow adds testing in a clean tree. In Subversion it looks almost like the simple commit:

dvcs-basic-svn-testing.png

wisp: Whitespace to Lisp

» I love the syntax of Python, but crave the simplicity and power of Lisp.«

display "Hello World!" ↦ (display "Hello World!")
define : factorial n     (define (factorial n)            
    if : zero? n       ↦     (if (zero? n)                
       . 1                      1                      
       * n : factorial {n - 1}  (* n (factorial {n - 1}))))

Wisp basics

»ArneBab's alternate sexp syntax is best I've seen; pythonesque, hides parens but keeps power« — Christopher Webber in twitter, in identi.ca and in his blog: Wisp: Lisp, minus the parentheses
☺ Yay! ☺
with (open-file "with.w" "r") as port
     format #t "~a\n" : read port
Familiar with-statement in 25 lines.

 ↓ skip updates ↓

Update (2018-06-26): There is now a wisp tutorial for beginning programmers: “In this tutorial you will learn to write programs with wisp. It requires no prior knowledge of programming.”Learn to program with Wisp, published in With Guise and Guile
Update (2017-11-10): wisp v0.9.8 released with installation fixes (thanks to benq!). To start your own wisp-project, see the tutorial Starting a wisp project. For more info, see the NEWS file. To test wisp v0.9.8, install Guile 2.0.11 or later and bootstrap wisp:
wget https://bitbucket.org/ArneBab/wisp/downloads/wisp-0.9.8.tar.gz;
tar xf wisp-0.9.8.tar.gz ; cd wisp-0.9.8/;
./configure; make check;
examples/newbase60.w 123
If it prints 23 (123 in NewBase60), your wisp is fully operational.
That’s it - have fun with wisp syntax!
Update (2017-10-17): wisp v0.9.7 released with bugfixes. To start your own wisp-project, see the tutorial Starting a wisp project. For more info, see the NEWS file. To test wisp v0.9.7, install Guile 2.0.11 or later and bootstrap wisp:
wget https://bitbucket.org/ArneBab/wisp/downloads/wisp-0.9.7.tar.gz;
tar xf wisp-0.9.7.tar.gz ; cd wisp-0.9.7/;
./configure; make check;
examples/newbase60.w 123
If it prints 23 (123 in NewBase60), your wisp is fully operational.
That’s it - have fun with wisp syntax!
Update (2017-10-08): wisp v0.9.6 released with compatibility for tests on OSX and old autotools, installation to guile/site/(guile version)/language/wisp for cleaner installation, debugging and warning when using not yet defined lower indentation levels, and with wisp-scheme.scm moved to language/wisp.scm. This allows creating a wisp project by simply copying language/. A short tutorial for creating a wisp project is available at Starting a wisp project as part of With Guise and Guile. For more info, see the NEWS file. To test wisp v0.9.6, install Guile 2.0.11 or later and bootstrap wisp:
wget https://bitbucket.org/ArneBab/wisp/downloads/wisp-0.9.6.tar.gz;
tar xf wisp-0.9.6.tar.gz ; cd wisp-0.9.6/;
./configure; make check;
examples/newbase60.w 123
If it prints 23 (123 in NewBase60), your wisp is fully operational.
That’s it - have fun with wisp syntax!
Update (2017-08-19): Thanks to tantalum, wisp is now available as package for Arch Linux: from the Arch User Repository (AUR) as guile-wisp-hg! Instructions for installing the package are provided on the AUR page in the Arch Linux wiki. Thank you, tantalum!
Update (2017-08-20): wisp v0.9.2 released with many additional examples including the proof-of-concept for a minimum ceremony dialog-based game duel.w and the datatype benchmarks in benchmark.w. For more info, see the NEWS file. To test it, install Guile 2.0.11 or later and bootstrap wisp:
wget https://bitbucket.org/ArneBab/wisp/downloads/wisp-0.9.2.tar.gz;
tar xf wisp-0.9.2.tar.gz ; cd wisp-0.9.2/;
./configure; make check;
examples/newbase60.w 123
If it prints 23 (123 in NewBase60), your wisp is fully operational.
That’s it - have fun with wisp syntax!
Update (2017-03-18): I removed the link to Gozala’s wisp, because it was put in maintenance mode. Quite the opposite of Guile which is taking up speed and just released Guile version 2.2.0, fully compatible with wisp (though wisp helped to find and fix one compiler bug, which is something I’m really happy about ☺).
Update (2017-02-05): Allan C. Webber presented my talk Natural script writing with Guile in the Guile devroom at FOSDEM. The talk was awesome — and recorded! Enjoy Natural script writing with Guile by "pretend Arne" ☺

presentation (pdf, 16 slides) and its source (org).
Have fun with wisp syntax!
Update (2016-07-12): wisp v0.9.1 released with a fix for multiline strings and many additional examples. For more info, see the NEWS file. To test it, install Guile 2.0.11 or later and bootstrap wisp:
wget https://bitbucket.org/ArneBab/wisp/downloads/wisp-0.9.1.tar.gz;
tar xf wisp-0.9.1.tar.gz ; cd wisp-0.9.1/;
./configure; make check;
examples/newbase60.w 123
If it prints 23 (123 in NewBase60), your wisp is fully operational.
That’s it - have fun with wisp syntax!
Update (2016-01-30): I presented Wisp in the Guile devroom at FOSDEM. The reception was unexpectedly positive — given some of the backlash the readable project got I expected an exceptionally sceptical audience, but people rather asked about ways to put Wisp to good use, for example in templates, whether it works in the REPL (yes, it does) and whether it could help people start into Scheme. The atmosphere in the Guile devroom was very constructive and friendly during all talks, and I’m happy I could meet the Hackers there in person. I’m definitely taking good memories with me. Sadly the video did not make it, but the schedule-page includes the presentation (pdf, 10 slides) and its source (org).
Have fun with wisp syntax!
Update (2016-01-04): Wisp is available in GNU Guix! Thanks to the package from Christopher Webber you can try Wisp easily on top of any distribution:
guix package -i guile guile-wisp
guile --language=wisp
This already gives you Wisp at the REPL (take care to follow all instructions for installing Guix on top of another distro, especially the locales).
Have fun with wisp syntax!
Update (2015-10-01): wisp v0.9.0 released which no longer depends on Python for bootstrapping releases (but ./configure still asks for it — a fix for another day). And thanks to Christopher Webber there is now a patch to install wisp within GNU Guix. For more info, see the NEWS file. To test it, install Guile 2.0.11 or later and bootstrap wisp:
wget https://bitbucket.org/ArneBab/wisp/downloads/wisp-0.9.0.tar.gz;
tar xf wisp-0.9.0.tar.gz ; cd wisp-0.9.0/;
./configure; make check;
examples/newbase60.w 123
If it prints 23 (123 in NewBase60), your wisp is fully operational.
That’s it - have fun with wisp syntax!
Update (2015-09-12): wisp v0.8.6 released with fixed macros in interpreted code, chunking by top-level forms, : . parsed as nothing, ending chunks with a trailing period, updated example evolve and added examples newbase60, cli, cholesky decomposition, closure and hoist in loop. For more info, see the NEWS file.To test it, install Guile 2.0.x or 2.2.x and Python 3 and bootstrap wisp:
wget https://bitbucket.org/ArneBab/wisp/downloads/wisp-0.8.6.tar.gz;
tar xf wisp-0.8.6.tar.gz ; cd wisp-0.8.6/;
./configure; make check;
examples/newbase60.w 123
If it prints 23 (123 in NewBase60), your wisp is fully operational.
That’s it - have fun with wisp syntax! And a happy time together for the ones who merge their paths today ☺
Update (2015-04-10): wisp v0.8.3 released with line information in backtraces. For more info, see the NEWS file.To test it, install Guile 2.0.x or 2.2.x and Python 3 and bootstrap wisp:
wget https://bitbucket.org/ArneBab/wisp/downloads/wisp-0.8.3.tar.gz;
tar xf wisp-0.8.3.tar.gz ; cd wisp-0.8.3/;
./configure; make check;
guile -L . --language=wisp tests/factorial.w; echo
If it prints 120120 (two times 120, the factorial of 5), your wisp is fully operational.
That’s it - have fun with wisp syntax!
Update (2015-03-18): wisp v0.8.2 released with reader bugfixes, new examples and an updated draft for SRFI 119 (wisp). For more info, see the NEWS file.To test it, install Guile 2.0.x or 2.2.x and Python 3 and bootstrap wisp:
wget https://bitbucket.org/ArneBab/wisp/downloads/wisp-0.8.2.tar.gz;
tar xf wisp-0.8.2.tar.gz ; cd wisp-0.8.2/;
./configure; make check;
guile -L . --language=wisp tests/factorial.w; echo
If it prints 120120 (two times 120, the factorial of 5), your wisp is fully operational.
That’s it - have fun with wisp syntax!
Update (2015-02-03): The wisp SRFI just got into draft state: SRFI-119 — on its way to an official Scheme Request For Implementation!
Update (2014-11-19): wisp v0.8.1 released with reader bugfixes. To test it, install Guile 2.0.x and Python 3 and bootstrap wisp:
wget https://bitbucket.org/ArneBab/wisp/downloads/wisp-0.8.1.tar.gz;
tar xf wisp-0.8.1.tar.gz ; cd wisp-0.8.1/;
./configure; make check;
guile -L . --language=wisp tests/factorial.w; echo
If it prints 120120 (two times 120, the factorial of 5), your wisp is fully operational.
That’s it - have fun with wisp syntax!
Update (2014-11-06): wisp v0.8.0 released! The new parser now passes the testsuite and wisp files can be executed directly. For more details, see the NEWS file. To test it, install Guile 2.0.x and bootstrap wisp:
wget https://bitbucket.org/ArneBab/wisp/downloads/wisp-0.8.0.tar.gz;
tar xf wisp-0.8.0.tar.gz ; cd wisp-0.8.0/;
./configure; make check;
guile -L . --language=wisp tests/factorial.w;
echo
If it prints 120120 (two times 120, the factorial of 5), your wisp is fully operational.
That’s it - have fun with wisp syntax!
On a personal note: It’s mindboggling that I could get this far! This is actually a fully bootstrapped indentation sensitive programming language with all the power of Scheme underneath, and it’s a one-person when-my-wife-and-children-sleep sideproject. The extensibility of Guile is awesome!
Update (2014-10-17): wisp v0.6.6 has a new implementation of the parser which now uses the scheme read function. `wisp-scheme.w` parses directly to a scheme syntax-tree instead of a scheme file to be more suitable to an SRFI. For more details, see the NEWS file. To test it, install Guile 2.0.x and bootstrap wisp:
wget https://bitbucket.org/ArneBab/wisp/downloads/wisp-0.6.6.tar.gz;
tar xf wisp-0.6.6.tar.gz; cd wisp-0.6.6;
./configure; make;
guile -L . --language=wisp
That’s it - have fun with wisp syntax at the REPL!
Caveat: It does not support the ' prefix yet (syntax point 4).
Update (2014-01-04): Resolved the name-clash together with Steve Purcell und Kris Jenkins: the javascript wisp-mode was renamed to wispjs-mode and wisp.el is called wisp-mode 0.1.5 again. It provides syntax highlighting for Emacs and minimal indentation support via tab. You can install it with `M-x package-install wisp-mode`
Update (2014-01-03): wisp-mode.el was renamed to wisp 0.1.4 to avoid a name clash with wisp-mode for the javascript-based wisp.
Update (2013-09-13): Wisp now has a REPL! Thanks go to GNU Guile and especially Mark Weaver, who guided me through the process (along with nalaginrut who answered my first clueless questions…).
To test the REPL, get the current code snapshot, unpack it, run ./bootstrap.sh, start guile with $ guile -L . (requires guile 2.x) and enter ,language wisp.
Example usage:
display "Hello World!\n"
then hit enter thrice.
Voilà, you have wisp at the REPL!
Caveeat: the wisp-parser is still experimental and contains known bugs. Use it for testing, but please do not rely on it for important stuff, yet.
Update (2013-09-10): wisp-guile.w can now parse itself! Bootstrapping: The magical feeling of seeing a language (dialect) grow up to live by itself: python3 wisp.py wisp-guile.w > 1 && guile 1 wisp-guile.w > 2 && guile 2 wisp-guile.w > 3 && diff 2 3. Starting today, wisp is implemented in wisp.
Update (2013-08-08): Wisp 0.3.1 released (Changelog).

Going from a simple Makefile to Autotools

Table of Contents

Links

Intro

I recently started looking into Autotools, to make it easier to run my code on multiple platforms.

Naturally you can use cmake or scons or waf or ninja or tup, all of which are interesting in there own respect. But none of them has seen the amount of testing which went into autotools, and none of them have the amount of tweaks needed to support about every system under the sun. And I recently found pyconfigure which allows using autotools with python and offers detection of library features.

Warning 2016: Contains some cargo-cult-programming — my current setup is cleaner thanks to using AC_CONFIG_LINKS in configure.ac.

Tail Call Optimization (TCO), dependency, broken debug builds in C and C++ — and gcc 4.8

TCO: Reducing the algorithmic complexity of recursion.
Debug build: Add overhead to a program to trace errors.
Debug without TCO: Obliterate any possibility of fixing recursion bugs.

“Never develop with optimizations which the debug mode of the compiler of the future maintainer of your code does not use.”°

UPDATE: GCC 4.8 gives us -Og -foptimize-sibling-calls which generates nice-backtraces, and I had a few quite embarrassing errors in my C - thanks to AKF for the catch!

1 Intro

Tail Call Optimization (TCO) makes this

def foo(n):
    print(n)
    return foo(n+1)
foo(1)

behave like this

def foo(n):
    print(n)
    return n+1
n = 1 while True: n = foo(n)

Test of the hg evolve extension for easier upstreaming

1 Rationale

PDF-version (for printing)

orgmode-version (for editing)

repository (for forking)

Currently I rework my code extensively before I push it into upstream SVN. Some of that is inconvenient and it would be nicer to have easy to use refactoring tools.

hg evolve might offer that.

This test uses the mutable-hg extension in revision c70a1091e0d8 (24 changesets after 2.1.0). It will likely be obsolete, soon, since mutable-hg is currently moved into Mercurial core by Pierre-Yves David, its main developer. I hope it will be useful for you, to assess the future possibilities of Mercurial today. This is not (only) a pun on “obsolete”, the functionality at the core of evolve which allows safe, collaborative history rewriting ☺

The dynamics of free culture and the danger of noncommercial clauses

NC covered works trick people into investing in a dead end

Free licensing lowers the barrier of entry to creating cultural works, which unlocks a dynamic where people can realize their ideas much easier - and where culture can actually live, creating memes, adjusting them to new situations and using new approaches with old topics.

But for that to really take off, people have to be able to make a living from their creations - which build on other works.

Neither Humble nor Indie Bundle

Update 2016: Later Bundles seem to have gotten better again.

Comment to New Humble Bundle Is Windows Only, DRM Games.

The new Humble Indie Bundle is no longer free, indie, cross-plattform or user-respecting.

When the first bundle had a huge boost in last-minute sales after the devs offered to free the source of 4 of the 5 games, I had hoped, they would keep that.

How to make companies act ethically

→ comment on Slashdot concerning Unexpected methods to promote freedom?

Was it really Apple who ended DRM? Would they have done so without the protests and evangelizing against DRM? Without protesters in front of Apple Stores? And without the many people telling their friends to just not accept DRM?

That “preaching” created a situation where Apple could reap monetary gain from doing the right thing.

Sending email to many people with Emacs Wanderlust

I recently needed to send an email to many people1.

Putting all of them into the BCC field did not work (mail rejected by provider) and when I split it into 2 emails, many did not see my mail because it was flagged as potential spam (they were not in the To-Field)2.

I did not want to put them all into the To-Field, because that would have spread their email-addresses around, which many would not want3.

So I needed a different solution. Which I found in the extensibility of emacs and wanderlust4. It now carries the name wl-draft-send-to-multiple-receivers-from-buffer.

You simply write the email as usual via wl-draft, then put all email addresses you want write to into a buffer and call M-x wl-draft-send-to-multiple-receivers-from-buffer. It asks you about the buffer with email addresses, then shows you all addresses and asks for confirmation.

Then it sends one email after the other, with a randomized wait of 0-10 seconds between messages to avoid flagging as spam.

If you want to use it, just add the following to your .emacs:

(defun wl-draft-clean-mail-address (address)
  (replace-regexp-in-string "," "" address))
(defun wl-draft-send-to-multiple-receivers (addresses) (loop for address in addresses do (progn (wl-user-agent-insert-header "To" (wl-draft-clean-mail-address address)) (let ((wl-interactive-send nil)) (wl-draft-send)) (sleep-for (random 10)))))
(defun wl-draft-send-to-multiple-receivers-from-buffer (&optional addresses-buffer-name) "Send a mail to multiple recipients - one recipient at a time" (interactive "BBuffer with one address per line") (let ((addresses nil)) (with-current-buffer addresses-buffer-name (setq addresses (split-string (buffer-string) "\n"))) (if (y-or-n-p (concat "Send this mail to " (mapconcat 'identity addresses ", "))) (wl-draft-send-to-multiple-receivers addresses))))

Happy Hacking!


  1. The email was about the birth of my second child, and I wanted to inform all people I care about (of whom I have the email address), which amounted to 220 recipients. 

  2. Naturally this technique could be used for real spamming, but to be frank: People who send spam won’t need it. They will already have much more sophisticated methods. This little trick just reduces the inconvenience brought upon us by the measures which are necessary due to spam. Otherwise I could just send a mail with 1000 receivers in the BCC field - which is how it should be. 

  3. It only needs one careless friend, and your connections to others get tracked in facebook and the likes. For more information on Facebook, see Stallman about Facebook

  4. Sure, there are also template mails and all such, but learning to use these would consume just as much time as extending emacs - and would be much less flexible: Should I need other ways to transform my mails, I’ll be able to just reuse my code. 

Bootstrapping the Freenet WoT with GnuPG - and GnuPG with Freenet

Intro

When you enter the freenet Web of Trust, you first need to get some trust from people by solving captchas. And even when people trust you somehow, you have no way to prove your identity in an automatic way, so you can’t create identities which freenet can label as trusted without manual intervention from your side.

Proposal

To change this, we can use the Web of Trust used in GnuPG to infer trust relationships between freenet WoT IDs.

Practically that means:

  • Write a message: “I am the WoT ID USK@” (replace with the

Easily converting ris-citations to bibtex with emacs and bibutils

The problem

Nature only gives me ris-formatted citations, but I use bibtex.

Also ris is far from human readable.

The background

ris can be reformatted to bibtext, but doing that manually disturbs my workflow when getting references while taking note about a paper in emacs.

I tend to search online for references, often just using google scholar, so when I find a ris reference, the first data I get for the ris-citation is a link.

The solution

Emacs

Cross platform, Free Software, almost all features you can think of, graphical and in the shell: Learn once, use for everything.

» Get Emacs «

Emacs is a self-documenting, extensible editor, a development environment and a platform for lisp-programs - for example programs to make programming easier, but also for todo-lists on steroids, reading email, posting to identi.ca, and a host of other stuff (learn lisp).

It is one of the origins of GNU and free software (Emacs History).

In Markdown-mode it looks like this:

Emacs mit Markdown mode

A complete Mercurial branching strategy

This is a complete collaboration model for Mercurial. It shows you all the actions you may need to take, except for the basics already found in other tutorials like

Adaptions optimize the model for special needs like maintaining multiple releases1, grafting micro-releases and an explicit code review stage.

Summary: 3 simple rules

Any model to be used by people should consist of simple, consistent rules. Programming is complex enough without having to worry about elaborate branching directives. Therefore this model boils down to 3 simple rules:

3 simple rules:

(1) you do all the work on default2 - except for hotfixes.

(2) on stable you only do hotfixes, merges for release3 and tagging for release. Only maintainers4 touch stable.

(3) you can use arbitrary feature-branches5, as long as you don’t call them default or stable. They always start at default (since you do all the work on default).

Diagram

To visualize the structure, here’s a 3-tiered diagram. To the left are the actions of programmers (commits and feature branches) and in the center the tasks for maintainers (release and hotfix). The users to the right just use the stable branch.6

Overview Diagram
An overview of the branching strategy. Click the image to get the emacs org-mode ditaa-source.

Table of Contents

Practial Actions

Now we can look at all the actions you will ever need to do in this model:7

  • Regular development

    • commit changes: (edit); hg ci -m "message"

    • continue development after a release: hg update; (edit); hg ci -m "message"

  • Feature Branches

    • start a larger feature: hg branch feature-x; (edit); hg ci -m "message"

    • continue with the feature: hg update feature-x; (edit); hg ci -m "message"

    • merge the feature: hg update default; hg merge feature-x; hg ci -m "merged feature x into default"

    • close and merge the feature when you are done: hg update feature-x; hg ci --close-branch -m "finished feature x"; hg update default; hg merge feature-x; hg ci -m "merged finished feature x into default"

  • Tasks for Maintainers

    • Initialize (only needed once)

      • create the repo: hg init reponame; cd reponame

      • first commit: (edit); hg ci -m "message"

      • create the stable branch and do the first release: hg branch stable; hg tag tagname; hg up default; hg merge stable; hg ci -m "merge stable into default: ready for more development"

    • apply a hotfix8: hg up stable; (edit); hg ci -m "message"; hg up default; hg merge stable; hg ci -m "merge stable into default: ready for more development"

    • do a release9: hg up stable; hg merge default; hg ci -m "(description of the main changes since the last release)" ; hg tag tagname; hg up default ; hg merge stable ; hg ci -m "merged stable into default: ready for more development"

That’s it. All that follows are a detailed example which goes through all actions one-by-one, adaptions to this workflow and the final summary.


  1. if you need to maintain multiple very different releases simultanously, see or 10 for adaptions 

  2. default is the default branch. That’s the named branch you use when you don’t explicitely set a branch. Its alias is the empty string, so if no branch is shown in the log (hg log), you’re on the default branch. Thanks to John for asking! 

  3. If you want to release the changes from default in smaller chunks, you can also graft specific changes into a release preparation branch and merge that instead of directly merging default into stable. This can be useful to get real-life testing of the distinct parts. For details see the extension Graft changes into micro-releases

  4. Maintainers are those who do releases, while they do a release. At any other time, they follow the same patterns as everyone else. If the release tasks seem a bit long, keep in mind that you only need them when you do the release. Their goal is to make regular development as easy as possible, so you can tell your non-releasing colleagues “just work on default and everything will be fine”. 

  5. This model does not use bookmarks, because they don’t offer benefits which outweight the cost of introducing another concept: If you use bookmarks for differenciating lines of development, you have to define the canonical revision to clone by setting the @ bookmark. For local work and small features, bookmarks can be used quite well, though, and since this model does not define their use, it also does not limit it.
    Additionally bookmarks could be useful for feature branches, if you use many of them (in that case reusing names is a real danger and not just a rare annoyance) or if you use release branches:
    “What are people working on right now?” → hg bookmarks
    “Which lines of development do we have in the project?” → hg branches 

  6. Those users who want external verification can restrict themselves to the tagged releases - potentially GPG signed by trusted 3rd-party reviewers. GPG signatures are treated like hotfixes: reviewers sign on stable (via hg sign without options) and merge into default. Signing directly on stable reduces the possibility of signing the wrong revision. 

  7. hg pull and hg push to transfer changes and hg merge when you have multiple heads on one branch are implied in the actions: you can use any kind of repository structure and synchronization scheme. The practical actions only assume that you synchronize your repositories with the other contributors at some point. 

  8. Here a hotfix is defined as a fix which must be applied quickly out-of-order, for example to fix a security hole. It prompts a bugfix-release which only contains already stable and tested changes plus the hotfix. 

  9. If your project needs a certain release preparation phase (like translations), then you can simply assign a task branch. Instead of merging to stable, you merge to the task branch, and once the task is done, you merge the task branch to stable. An Example: Assume that you need to update translations before you release anything. (next part: init: you only need this once) When you want to do the first release which needs to be translated, you update to the revision from which you want to make the release and create the “translation” branch: hg update default; hg branch translation; hg commit -m "prepared the translation branch". All translators now update to the translation branch and do the translations. Then you merge it into stable: hg update stable; hg merge translation; hg ci -m "merged translated source for release". After the release you merge stable back into default as usual. (regular releases) If you want to start translating the next time, you just merge the revision to release into the translation branch: hg update translation; hg merge default; hg commit -m "prepared translation branch". Afterwards you merge “translation” into stable and proceed as usual. 

  10. If you want to adapt the model to multiple very distinct releases, simply add multiple release-branches (i.e. release-x). Then hg graft the changes you want to use from default or stable into the releases and merge the releases into stable to ensure that the relationship of their changes to current changes is clear, recorded and will be applied automatically by Mercurial in future merges11. If you use multiple tagged releases, you need to merge the releases into each other in order - starting from the oldest and finishing by merging the most recent one into stable - to record the same information as with release branches. Additionally it is considered impolite to other developers to keep multiple heads in one branch, because with multiple heads other developers do not know the canonical tip of the branch which they should use to make their changes - or in case of stable, which head they should merge to for preparing the next release. That’s why you are likely better off creating a branch per release, if you want to maintain many very different releases for a long time. If you only use tags on stable for releases, you need one merge per maintained release to create a bugfix version of one old release. By adding release branches, you reduce that overhead to one single merge to stable per affected release by stating clearly, that changes to old versions should never affect new versions, except if those changes are explicitely merged into the new versions. If the bugfix affects all releases, release branches require two times as many actions as tagged releases, though: You need to graft the bugfix into every release and merge the release into stable.12 

  11. If for example you want to ignore that change to an old release for new releases, you simply merge the old release into stable and use hg revert --all -r stable before committing the merge. 

  12. A rule of thumb for deciding between tagged releases and release branches is: If you only have a few releases you maintain at the same time, use tagged releases. If you expect that most bugfixes will apply to all releases, starting with some old release, just use tagged releases. If bugfixes will only apply to one release and the current development, use tagged releases and merge hotfixes only to stable. If most bugfixes will only apply to one release and not to the current development, use release branches. 

Recipes for presentations with beamer latex using emacs org-mode

I wrote some recipes for creating the kinds of slides I need with emacs org-mode export to beamer latex.

Update: Read ox-beamer to see how to adapt this to work with the new export engine in org-mode 0.8.

PDF recipes The recipes as PDF (21 slides, 247 KiB)

org-mode file The org-mode sources (12.2 KiB)

Below is an html export of the org-mode file. Naturally it does not look as impressive as the real slides, but it captures all the sources, so I think it has some value.

Note: To be able to use the simple block-creation commands, you need to add #+startup: beamer to the header of your file or explicitely activate org-beamer with M-x org-beamer-mode.

«I love your presentation»:

PS: I hereby allow use of these slides under any of the licenses used by worg and/or the emacs wiki.

Der Kohlenstoffkreislauf | The carbon cycle (slides)

I did a 10 minute talk about the basics of the carbon cycle. Since I think that it worked out quite well, I’m publishing the slides here under the GPL (=licensed free and copyleft).

Ich habe einen 10 Minuten Vortrag zu den grundlegenden Mechanismen des Kohlenstoff­kreislaufs gehalten. Da er meiner Meinung nach gut geworden ist, veröffentliche ich ihn hier unter der GPL (=frei und copyleft lizensiert).
 

Carbon Cycle, a short overview
The carbon cycle, a short overview (pdf)

Dieser Text ist mir was wert:


If you want to use it, you can directly work on my source files:

Falls ihr ihn nutzen wollt, könnt ihr direkt meine Quelldateien verwenden:


Remember: GPL means: name previous authors, publish your source files and put what you create with it under the GPL, too.

Denk daran: GPL heißt: Nennt die Vorautoren, veröffentlicht eure Quellen und stell damit erstelltes auch unter die GPL.


  1. Die Bilder stammen aus Battle for Wesnoth 

Open Letter to Julia Hilden on her article about pay-per-use

I just read your article on per use payments.

I think there are two serious flaws in per use payments:

(a) Good works of art need to last

As you stated correctly, I define myself partly through the media I "consume".

This does mean, that I want to have the assurance, that I can watch a great movie again a few years in the future.

Imagine this scenario:

  • I found a really great book, read it and got entranced.
  • It's 20 years later, now. and I want to read the book to my children.

Background of Freenet Routing and the probes project (GSoC 2012)

The probes project is a google summer of code project of Steve Dougherty intended to optimize the network structure of freenet. Here I will give the background of his project very briefly:

The Small World Structure

Minimal example for literate programming with noweb in emacs org-mode

If you want to use the literate programming features in emacs org-mode, you can try this minimal example to get started: Activate org-babel-tangle, then put this into the file noweb-test.org:

Minimal example for noweb in org-mode

* Assign 

First we assign abc:

#+begin_src python :noweb-ref assign_abc
abc = "abc"
#+end_src

* Use

Then we use it in a function:

#+begin_src python :noweb tangle :tangle noweb-test.py
def x():
  <<assign_abc>>
  return abc

print(x())
#+end_src

noweb-test.org

The ease of losing the spirit of your project by giving in to short-term convenience

Yesterday I said to my father

» Why does your whole cooperative have to meet for some minor legalese update which does not have an actual effect? Could you not just put into your statutes, that the elected leaders can take decisions which don’t affect the spirit of the statutes? «

He answered me

» That’s how dictatorships are started.«

With an Ermächtigungsbescheid.

I gulped a few times while I realized how easy it is to fall into the pitfalls of convenience - and lose the project in the process.

Inhalt abgleichen
Willkommen im Weltenwald!
((λ()'Dr.ArneBab))



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