| Andrew Cooke | Contents | Latest | RSS | Twitter | Previous | Next


Welcome to my blog, which was once a mailing list of the same name and is still generated by mail. Please reply via the "comment" links.

Always interested in offers/projects/new ideas. Eclectic experience in fields like: numerical computing; Python web; Java enterprise; functional languages; GPGPU; SQL databases; etc. Based in Santiago, Chile; telecommute worldwide. CV; email.

Personal Projects

Lepl parser for Python.

Colorless Green.

Photography around Santiago.

SVG experiment.

Professional Portfolio

Calibration of seismometers.

Data access via web services.

Cache rewrite.

Extending OpenSSH.

C-ORM: docs, API.

Last 100 entries

Re: Quick message - This link is broken; Adding Reverb To The Echo Chamber; Sox Audio Tools; Would This Have Been OK?; Honesty only important economically before institutions develop; Stegangraphy via PS4; OpenCL Mess; More Book Recommendations; Good Explanation of Difference Between Majority + Minority; Musical Chairs - Who's The Privileged White Guy; I can see straight men watching this conversation and laffing; When it's Actually a Source of Indignation and Disgust; Meta Thread Defending POC Causes POC To Close Account; Indigenous People Of Chile; Curry Recipe; Interesting Link On Marginality; A Nuclear Launch Ordered, 1962; More Book Recs (Better Person); It's Nuanced, And I Tried, So Back Off; Marx; The Negative Of Positive; Jenny Holzer Rocks; Huge Article on Cultural Evolution and More; "Ignoring language theory"; Negative Finger Counting; Week 12; Communication Via Telecomm Bids; Finding Suspects Via Relatives' DNA From Non-Crime Databases; Statistics and Information Theory; Ice OK in USA; On The Other Hand; (Current Understanding Of) Chilean Taxes / Contributions; M John Harrison; Playing Games on a Cloud GPU; China Gamifies Real Life; Can't Help Thinking It's Thoughtcrime; Mefi Quotes; Spray Painting Bike Frame; Weeks 10 + 11; Change: No Longer Possible To Merge Metadata; Books on Old Age; Health Tree Maps; MRA - Men's Rights Activists; Writing Good C++14; Risk Assessment - Fukushima; The Future of Advertising and Surveillance; Travelling With Betaferon; I think I know what I dislike so much about Metafilter; Weeks 8 + 9; More; Pastamore - Bad Italian in Vitacura; History Books; Iraq + The (UK) Governing Elite; Answering Some Hard Questions; Pinochet: The Dictator's Shadow; An Outsider's Guide To Julia Packages; Nobody gives a shit; Lepton Decay Irregularity; An Easier Way; Julia's BinDeps (aka How To Install Cairo); Good Example Of Good Police Work (And Anonymity Being Hard); Best Santiago Burgers; Also; Michael Emmerich (Vibrator Translator) Interview (Japanese Books); Clarice Lispector (Brazillian Writer); Books On Evolution; Looks like Ara (Modular Phone) is dead; Index - Translations From Chile; More Emotion in Chilean Wines; Week 7; Aeon Magazine (Science-ish); QM, Deutsch, Constructor Theory; Interesting Talk Transcripts; Interesting Suggestion Of Election Fraud; "Hard" Books; Articles or Papers on depolarizing the US; Textbook for "QM as complex probabilities"; SFO Get Libor Trader (14 years); Why Are There Still So Many Jobs?; Navier Stokes Incomplete; More on Benford; FBI Claimed Vandalism; Architectural Tessellation; Also: Go, Blake's 7; Delusions of Gender (book); Crypto AG DID work with NSA / GCHQ; UNUMS (Universal Number Format); MOOCs (Massive Open Online Courses); Interesting Looking Game; Euler's Theorem for Polynomials; Weeks 3-6; Reddit Comment; Differential Cryptanalysis For Dummies; Japanese Graphic Design; Books To Be Re-Read; And Today I Learned Bugs Need Clear Examples; Factoring a 67 bit prime in your head; Islamic Geometric Art; Useful Julia Backtraces from Tasks; Nothing, however, is lost with less discomfort than that which, when lost, cannot be missed; Article on Didion

© 2006-2015 Andrew Cooke (site) / post authors (content).

Using libxml (libxml2) with Namespaces

From: andrew cooke <andrew@...>

Date: Mon, 18 Jul 2011 11:31:46 -0400

This has just cost me more time than it should have - I was generating a
validating XML document in C, using libxml2 (via the tree API), but when I
wrote the document to a file, the xmlns namespace declaration was missing.
All the elements has a namespace prefix, but that prefix was not defined.

So an example file looked like:

  <?xml version="1.0" encoding="UTF-8"?>
    <stn:Station net_code="13050" sta_code="KIV1"/>
    <stn:Station net_code="z" sta_code="XYZ"/>

This is the same issue mentioned here
http://mail.gnome.org/archives/xml/2005-April/msg00116.html but the reply is
less than helpful.

Anyway... after much experimenting, it turns out that the following sequence

  1 - Create the document
  2 - Create the root node
  3 - Create the namespace, passing the root node as first argument
  4 - Set the namespace on the root node using xmlSetNs
  5 - Add the root node to the document

Not all of that is important (but I am describing it exactly as I know that
order works).  The root of the problem is that constructors for both nodes and
namespaces take namespaces and nodes as arguments (respectively) which gives a
chicken-and-egg situation.  xmlSetNS cuts the Gordian knot and creates the
primordial chicken.

Also, with the above, you should not free the namespace (before, when the two
were insufficiently connected, I was freeing the namespace; now, that causes a
double-free segfault).

The final document then looks like:

  <?xml version="1.0" encoding="UTF-8"?>
  <stn:StaMessage xmlns:stn="http://www.data.scec.org/xml/station/">
    <stn:Station net_code="13050" sta_code="KIV1"/>
    <stn:Station net_code="z" sta_code="XYZ"/>

(I still can't work out how to set a default namespace).


Using libxml (libxml2) with Namespaces

From: levent oturak <levent@...>

Date: Wed, 29 Jan 2014 16:45:28 +0100

Hi Andrew,
thank you for your Posting on http://www.acooke.org/cute/Usinglibxm0.html.
I am writing a simple Code to create a XML File.
How can I get your result root Element without Namespace
I mean following:

  <?xml version="1.0" encoding="UTF-8"?>
  <StaMessage xmlns:stn="http://www.data.scec.org/xml/station/">
    <stn:Station net_code="13050" sta_code="KIV1"/>
    <stn:Station net_code="z" sta_code="XYZ"/>

Thanx im Advance

Best regards

Comment on this post