C11 function overloading

About four years ago, the ISO 9899:2011 "C11" standard was announced. At the time, I had a short look at (a draft version of) the standards document, and found a few interesting bits in there. Of course, however, due to it only very recently having been released, I did not have much hope of it being implemented to any reasonable amount anywhere yet. Which turned out to be the case. Even if that wasn't true, writing code that uses C11 features and expecting it to work just about anywhere else would have been a bad idea back then.

We're several years down the line now, however, and now the standard has been implemented to a reasonable extent in most compilers. GCC claims its "support [for C11] is at a similar level of completeness to (...) C99 support" since GCC 4.9.

Since my laptop has GCC 4.9, I looked at one feature in C11 that I have been wanting to use for a while: Generic selection.

#include <stdint.h>
#include <inttypes.h>
#include <stdio.h>

void say32(uint32_t i) {
    printf("32-bit variable: %" PRId32 "\n", i);

void say64(uint64_t i) {
    printf("64-bit variable: %" PRId64 "\n", i);

void sayother(int i) {
    printf("This is something else.\n");

#define say(X) _Generic((X), uint32_t: say32, uint64_t: say64, default: sayother)(X)

int main(void) {
    uint32_t v32 = 32;
    uint64_t v64 = 64;
    uint8_t v8 = 8;


Output of the above:

32-bit variable: 32
64-bit variable: 64
This is something else.

or, "precompiler-assisted function overloading for C". Should be useful for things like:

#define ntoh(X) _Generic((X), int16_t: ntohs, uint16_t: ntohs, int32_t: ntohl, uint32_t: ntohl)(X)
#define hton(X) _Generic((X), int16_t: ntohs, uint16_t: htons, int32_t: ntohl, uint32_t: htonl)(X)

... and if one adds the ntohll found here, it can do 64 bit as well.

LOADays 2015 talk done

I just uploaded my LOADays 2015 slides to slideshare. The talk seems to have been well received; I got a number of positive comments from some attendees, which is always nice.

As an aside, during the talk I did a short demo of how to sign something from within Libreoffice using my eID card. Since the slides were made in Libreoffice Impress, the easiest thing to do was just to sign the slides themselves, which worked perfectly well. So, having uploaded, downloaded, and verified these slides, I can now say with 100% certainty that slideshare does not tamper with files you upload. They may reformat them so it's easier to view on a website, but if you click on the download link, you get the original, untampered version.

At least that's the case if you sign documents, of course; it's always possible that they check for that and special-case such things. Would surprise me, though.

Youn Sun Nah 5tet: Light For The People

About a decade ago, I played in the (now defunct) "Jozef Pauly ensemble", a flute choir connected to the musical academy where I was taught to play the flute. At the time, this ensemble had the habit of goin on summer trips every year; sometimes these trips were large international concert tours (like our 2001 trip to Australia), but that wasn't always the case; there have also been smaller trips, like the 2002 one to the French Ardennes.

While there, we went on a day trip to the city of Reims. As a city close to the front in the first world war, it has a museum dedicated to that subject that I remembered going to. But the fondest memory of that day was going to a park where a podium was set up, with a few stacks of fold-up chairs standing nearby. I took one and listened to the music.

That was the day when I realized that I kindof like jazz. I had come into contact with Jazz before, but it had always been something to be used as a kind of musical wallpaper; something you put on, but don't consciously listen to. Watching this woman sing, however, was a different kind of experience altogether. I'm still very fond of her rendition of "Besame Mucho".

After having listened to the concert for about two hours, they called it quits, but did tell us that there was a record which you could buy. Of course, after having enjoyed the afternoon so much, I couldn't imagine not buying it, so that happened.

Fast forward several years, in the move from my apartment above my then-office to my current apartment (just around the corner), the record got put into the wrong box, and when I unpacked things again it got lost; permanently, I thought. Since I also hadn't digitized it yet at the time, I haven't listened to it anymore in quite a while.

But that time came to an end today. The record which I thought I'd lost wasn't, it was just in a weird place, and while cleaning yesterday, I found it sitting among a bunch of old stuff that I was going to throw out. Putting on the record today made me realize again how good it really is, and I thought that I might want to see if she was still active, and if she might perhaps have made another album.

It was great to find out that not only had she made six more albums since the one I bought, she'd also become a lot more known in the Jazz world (which I must admit I don't really follow all that well), and won a number of awards.

At the time, Youn Sun Nah was just a (fairly) recent graduate from a particular Jazz school in Paris. Today, she appears to be so much more...