Martin Geisler Online

I’ve just sent an email to the teaching assistant with the Object Spyglass project which I’ve been working on the last couple of weeks together with Peter Brandt in the Object-Oriented Software Construction class at the [ETH][].

It’s nice to have it done, and in the end it turned out quite well I think. Take a look for your self:

• Project Requirements: XHTML or PDF,
• User’s Guide: XHTML or PDF
• Developer’s Guide: XHTML or PDF.

You can also download everything, including the Eiffel source code, as object-spyglass.tar.gz or object-spyglass.zip if you’re interested.

An interesting thing (at least for me as a big [LaTeX][] fan) is the way the documentation was produced: the [XHTML][] documents were translated into beautiful LaTeX code in a fully automated way using eXtensible Stylesheet Language Transformations (XSLT). That is just way too cool, for now I have two versions for free! And both look quite good IMHO… :-) The stylesheet (which I didn’t write completely from scratch) is also included.

Once again it’s summer here in Switzerland! This time it’s for real: we’ve had temperatures of more than 30 °C (that’s 86 °F for you American guys…) the last couple of days. Stéphanie has switched from normal coffee to ice coffee and I’ve begun putting ice cubes in my milk…

The huge thunderstorm we had two days ago didn’t really cool things down as much as one could have hoped — the weather forecasts promise more thunder next week and a little lower temperatures, a “cool” 25°C :-)

Tonight we had a huge thunderstorm, which could be seen from our balcony. It was quite intensive, even though it was not directly over Buchs but nearby to the East.

I went out on our balcony, equipped with my trusty SONY DSC-V1 digital camera, wanting to see if I could capture a bolt of lightning with it. And I succeeded! I’ve never been able to shoot at the right moment before, but tonight was my lucky night :-)

The first photo is taken with a shutter speed of 2 seconds, and that’s why the sky has turned quite blue even though it’s half past ten in the evening.

The second photo was taken with a smaller exposure, just half a second. In both photos one can see the “skyline” of Buchs at the bottom :-) We actually have a really nice view from our balcony of our apartment — of nothing in particular, but nice anyway.

I’ve finally booked flights for me and Stéphanie for the summer! We’re going to the U2 Vertigo concert in Copenhagen on the 31th of July, and after that I’ll be going to Århus and Aalborg to visit friends and family while Stéphanie goes back.

We’ll arrive in Copenhagen on July the 31th with a flight from SWISS and Stéphanie will go back already on August the 2nd. I’ll then take a bus to Århus and Aalborg and first go back two weeks later on the 16th of July.

In those two weeks I hope to visit lots of people in both Århus and Aalborg!

That was the dates — now let me tell you about the booking experience… First of all: it’s a jungle trying to find the cheapest flight from A to B. There’s the cheap airlines like EasyJet and Ryanair, and I’ve flown with them before without any problems. But neither of them fly directly from Switzerland to Copenhagen which means that you’ll have to go by either London Stansted or Berlin and this complicates the whole thing, and is also likely to make the total cost higher than a direct flight.

About the total cost, then that’s a bit silly too: half of what you pay is called fuel, fees and taxes. And you’ll only see those at the end of your booking. I understand that the airline companies have to pay something to the airports to be allowed to land there, but could they not just include that in the price? That would make things more transparent when you’re comparing prices — ups, perhaps that’s why they haven’t done it! :-)

Finally a technical thing: the SWISS online booking system cannot handle two concurrent bookings made in the same browser. When trying to do so, you get this nice little warning:

Sorry: our system is unable to continue this transaction. Entering multiple inquiries or using the “Back” function of your browser can cause the system to freeze. Please close your internet window completely and start again.

I would suspect that they store the session data in a cookie, and thus the two tabs or browser windows will use the same cookie. That’s a shame, for making two concurrent bookings is exactly what I had to do in my case where Stéphanie and I will be flying back on different dates. And it’s not that it’s technically impossible to support multiple concurrent sessions in the same browser: it just requires that the session ID is embedded in the page and not in a cookie — EasyJet does it like this. A small detail in the implementation with a big impact on the functionality of the system as a whole.

Using Linux it was easy to overcome this limitation anyway: I simply logged in as another user, exported $DISPLAY to :0.0 and started another Firefox. Before doing this you’ll have to give the other user access to your X server, do this by copying your ~/.Xauthority file to the home directory of the other user. An alternative is to make a symbolic link to it and then ensure that the other user is able to read it (with root this works very nicely).

Another, more heavy-weight, solution would be to spawn a new display using something like GDM Flexiserver, but just copying or linking the ~/.Xauthority file is much easier, IMHO.

I was browsing through my old reports from way back in primary and high-school. That brought back some memories… I found lots of short stories from my Danish and English classes — it’s very cute to see a two-page summary of some English text which I now don’t even remember reading :-)

There were also bigger reports among my old stuff: a report from a class excursion to Nordjyllandsværket, our local power plant in Aalborg. Our class also made an excursion to Dansk Eternit where we made tests with breaking their fibre-cement roof elements. I might put those online someday if I can get them converted.

The reports and texts from my primary school days were all written in Microsoft Word — I had not yet seen [the light][LaTeX] back then… :-) During high-school I started using [LaTeX][], and now I’m glad I did: the DVI files still exactly like they did those five years ago!

With the Word files things are a bit more difficult: OpenOffice is able to open them all without problem and the text is there with the correct formatting. The embedded images are also there and OLE stuff like Equation Editor objects and vector drawings from the venerable CorelDRAW are generally there too, although some of them looked a little weird.

There’s also the problem that I no longer have programs like CorelDRAW, so I’m no longer able to edit those images — I have basically reached a dead-end in the upgrade path when I switched to Linux. With programs like MetaPost I don’t have to be afraid of that — it’s free so I’ll have access to MetaPost today, tomorrow and in ten years.

If you’re a normal Windows user, then you might be thinking something along the lines of “What about incompatibilities between new and old versions?” Fear not! Stability is a major concern for people in the LaTeX world (and MetaPost is primarily used with LaTeX). I believe this is so because LaTeX is a tool used for serious stuff where one would actually loose huge amounts of money if something “suddenly” changes. A twenty page document written in Word doesn’t count at serious stuff — a 1000 page book in LaTeX does.

There you want to be absolutely certain that everything looks the same as the first edition when you begin preparing a second edition. So TeX itself is now frozen and all changes to LaTeX are made with much care so as to not disturb existing documents.

Despite the grieves over MS Word it was an enjoyable tour through the good old days!