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Tag: XML

WW challenge 1: learning better C by working on XJot

Since the beginning of this month (October 2021), I become officially jobless, after 6 years at YTEC. That’s not so much of a problem for a software developer in 2021—especially one in the Dutch IT industry, where there has been an enormous shortage of skilled developers for years. However… I don’t (yet) want a new job as a software developer, because: in the programming food pyramid, I’m a mere scripter. That is, the language in which I’m most proficient are all very high-level languages: Python, PHP, XSLT, Bash, JavaScript, Ruby, C# (in order of decreasing (recency of) experience. I have never mastered a so-called systems language: C, C++, Rust.

Now, because of the circumstances in which YTEC and I decided to terminate the contract, I am entitled to government support until I find a new job. During my last job, I’ve learned a lot, but almost all I learned made me even more high-level and business-leaning than I already was. I’ve turned into some sort of automation & integration consultant / business analyst / project manager. And, yes, I’ve sharpened some of my code organization, automated testing skills as well. Plus I now know how to do proper monitoring. All very nice and dandy. But, what I’m still missing are ① hardcore, more low-level technical skills, as well as ② front-end, more UX-oriented skills. Only with some of those skills under my belt will I be able to do the jobs I really want to do—jobs that involve ① code that has to actually work efficient on the hardware level—i.e., code that doesn’t eat up all the hardware resources and suck your battery (or your “green” power net) empty; and I’m interested in making (website) application actually pleasant (and accessible!) to use.

If I start applying for something resembling my previous job, I will surely find something soon enough. However, first I am to capture these new skills, if I also wish to continue to grow my skill-level, my self-respect, as well as my earning (and thus tax paying) potential. Hence, the WW challenge. WW is the abbreviation for Wet Werkeloosheid, a type of welfare that Dutchies such as myself get when they temporarily are without job, provided that you were either ⓐ fired or ⓑ went away in “mutual understanding” (as I was). If ⓒ you simply quit, you don’t have the right to WW (but there are other fallbacks in the welfare state of the NL).

Anyways, every month, I have to provide the UWV—the governmental organization overseeing people in the WW—with evidence of my job-seeking activities. Since I decided that I want to deepen my knowledge instead of jumping right back into the pool of IT minions, I will set myself challenges that require the new skills I desire.

My first goal is to become more comfortable with the C programming language. I have some experience with C, but my skill level is rudimentary at best. My most recent attempt to become more fluent in C was that I participated in the 2020 Advent of Code challenge. I didn’t finish that attempt, because, really, I’m a bread programmer. Meaning: before or after a 8+-hour day at the office, I have very little desire to spend my free time doing even more programming. To stay sane (and steer clear of burnout), that time is much-needed for non-digital activities in social space, in nature, and by inhabiting my physical body.

So now I do have time and energy to learn some new skills that really require sustained focus over longer periods of time to acquire. On the systems programming language level, besides C, I’m also interested in familiarizing myself with C++ and Rust. And it is a well-known facts that C knowledge transfers very well to these two languages.

Okay, instead of doing silly Christmas puzzles, this time I’ve resumed my practice by writing an actual program in C that is useful to me: xjot-to-xml. It will be a utility to convert XJot documents to regular XML. XJot is an abbreviated notation for XML, to make it more pleasant to author XML documents—especially articles and books.

Installing XML catalogs on Archlinux

It took me forever to find the packages on Archlinux that contained the XML catalogs files for HTML and XHTML. So:

aur/html-docs
aur/xhtml-docs

It installs a file in /etc/profile.d and sets SGML_CATALOG_FILES, so be sure to su – or login again.

Styling XML SVN logs with CSS

My friend, Wiebe, keeps his website in Subversion. (Always keep your project files in version management or you’ll be sorry.) He used to manually track the date with the last significant change in each file (because who cares about typos, right?). But, of course, he kept forgetting to update this when he actually made such changes. So, he decided that he wanted to publish the full SVN log for each page.

The raw SVN logs are a bit raw, reason enough to try to turn it in something prettier. Luckily, there’s no need to parse the log files, because svn log has a command-line option, --xml. This option causes the log file to be printed in a simple XML format:

<?xml version="1.0"?>
<log>
<logentry revision="345">
<author>halfgaar</author>
<date>2009-05-25T10:50:07.560914Z</date>
<msg>Added very useful note to index about an awkward sentence.
</msg>
</logentry>
<!-- Snipped the rest of the logentry elements -->
</log>

Now we can use any number of ready-to-use XML tools to process this log, but I figured that, maybe, a very simple solution could work: CSS. Cascasing Stylesheets can be used for more than just styling HTML. One of the few differences is that with non-HTML XML, there are no defaults for the CSS properties (and aren’t we always trying to discover and override the various browser-specific CSS defaults anyway?)

First, we want to add a <?xml-stylesheet?> processing instruction to the log file:

svn log --xml example_file.xhtml | sed -e '/<\?xml / a<?xml-stylesheet type="text/css" media="screen" href="/css/svn-log.css"?>'

The XML file now references the CSS file that we’re going to make:

<?xml version="1.0" encoding="UTF-8"?>
<?xml-stylesheet type="text/css" media="screen" href="svn-log.css"?>
<!-- snip -->

svn-log.css:

log {
 :;
 :('http://svn.collab.net/repos/svn/trunk/notes/logo/256-colour/subversion_logo-200x173.png');
 :;
 :;
 :;
 :;
 : 2em 204px 2em 5ex;
}
 
logentry {
 :;
 :;
 : 1em;
 :;
 :;
 : #999;
}
 
author {
 :;
}
 
date {
 :;
 : 10ex;
  /* If Firefox would support font families even when you force a font,
     I could use 'overflow: hidden' to hide everything except the date part of <date>. */
 :;
 :; 
 :;
 :;
 : 110%;
 : #7488a7;
}
 
msg {
 :;
 : pre-wrap;
 :;
}

We now have a nicely formatted log file. Other things you could do:

  • Add styles for printing (in a separate stylesheet or by using @media blocks).
  • Display the revision author instead of hiding it.

Of course, you could do all this and much more with XSLT, but that’s just all too obvious. 🙂

If you want to see the stylesheet in action, take a look at Wiebe’s website and look for a View revision log of this page link in the footer of any of his pages.

XML SVN log styled with CSS

XML SVN log styled with CSS

Moved from Mnemosyne to FlashcardDB

When I was studying Spanish last year, I had to choose a flashcard program to memorize new words. At the time, I couldn’t find any on-line program that just did the job and did it well. In a comment on my blog post from last year, however, I was pointed by Jeff to his amazing FlashcardDB.

The program I ended up with last year was Mnemosyne. Mnemosyne is not based on your regular Leitner system, but rather on a concept where, after each card, you have to indicate yourself how well you have remembered it. I found that, in the end, having to tell the system in which box to put the card instead of just saying if my answer was right or wrong was taking me more effort than the actual recollection of the information. Also, as someone who rarely remains at one place for very long, a desktop program just isn’t as practical for me as an online program.

Mnemosyne
With Mnemosyne, I had to constantly remind myself of a complicated grading system.

Now to FlashcardDB. The site is pretty social, which means that you can study (and sometimes even edit) card sets made by other users. When you sign up, you can also create card sets yourself. Card sets can be tagged and you can study these tags instead of individual card sets if you wish. If you already have cards somewhere else, import is easy as well.

The user interface is very slick, especially for such a new program. Thoughtful usage of AJAX means that you’re never distracted by page reloads when this would interrupt your flow of thought. Simple key bindings making studying an easier affair than in most desktop programs. The right arrow is used to show the answer, the up arrow (thumbs up) to mark the answer as correct, the down arrow (thumbs down) to mark the answer incorrect and the left arrow to go back to the previous card. Also the interface for adding cards is very pleasant. It’s just a matter of filling in the front of the card, pressing Tab, filling in the back of the card, pressing Tab, then Enter and on the next card.

Before going on to the conclusion, I want to add that also the Leitner system is very well implemented in FlashcardDB, including pretty diagrams to make it instantly clear to everyone how the system works. Now for my conclusion: My advice if you ever need to make flashcards yourself is that you really should take a look at FlashcardDB before looking at anything else.

Finally, the following Ruby code is a quick hack I used to convert Mnemosyne’s XML export to CSV data which can be imported by FlashcardDB:

#!/usr/bin/ruby
 
require 'rexml/document'
require 'csv'
 
xmldoc = REXML::Document.new($stdin)
 
CSV::Writer.generate($stdout) do |csv|
  xmldoc.each_element('//item') do |el|
    csv << [  el.elements[1,'Q'].text, el.elements[1,'A'].text  ]
  end
end

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