Well, that's pretty much it. Four weeks ago I began a four-week break from work; so tomorrow I'll be back in the office, probably struggling through a month of email backlog to begin with and then resuming the big project I was in the middle of implementing when my sabbatical began. (Which was pretty silly timing, but sabbaticals are booked six months in advance and the big project came up on shorter notice than that…)

When my company introduced the sabbatical scheme, I'm sure I remember them trying to encourage people to use the break to do something constructive or at least purposeful. Last time I had one, four years ago, I used it to do some serious PuTTY development including porting some big chunks of PuTTY to Unix, which seemed pretty constructive to me.

Nowadays the company doesn't seem to be emphasising that angle so much; I suppose they must have accustomed themselves to the idea that if you give people four weeks off work it's going to take more than well-meaning encouragement to stop most of them from treating it as a four-week holiday. When I left work four weeks ago they just said ‘enjoy your break’. Regardless of this, I wanted to do something useful with my time, and I had laid plans for some far-reaching PuTTY infrastructure renovation. Unfortunately, it was not to be.

I spent the first week lying on the sofa watching DVDs, punctuated by an occasional walk to Blockbuster to rent a succession of films I'd recently failed to go and see in the cinema. By the end of that week I was feeling rested and energetic enough to want to do something useful, which was pretty much how I'd planned it. But at that point the machine on which I read my email changed its spam-filtering configuration and I suddenly found myself deluged with a flood of Japanese newsletters and stock-market scam mail from which it was quite difficult to pick out anything legitimate; so I hastily changed direction and devoted a couple of weeks to writing some spam-filtering code which would solve my immediate problems. As a result, my inbox is now quieter than it's been in months and I have some reasonably convenient ways to make it quieter still as necessary, but PuTTY's data storage infrastructure remains stubbornly unrenovated.

I suppose I should be glad that the spam emergency came up when I did have time and energy available to devote to it; if I hadn't been on sabbatical last month then I might still be struggling with it now. But I can't help feeling somewhat peeved that a bunch of spammers stopped me from having the time and energy to do what I really wanted to do with that month of freedom.

Still; aside from that annoyance it hasn't been a bad month. Even though I haven't written the code I'd hoped to write, I have at least reassured myself that I can still write useful code in contexts other than work; and I've had time to laze around, time to sort out various things that have needed sorting out, and time left over to spend with a variety of nice people who I don't see nearly enough of. So, could have been a lot worse really.

‘Captain Waterhouse? You are to proceed to the Mansion,’ says the guard who had spoken on the telephone. ‘You can't miss it.’

Waterhouse walks for about fifty feet and finds that the Mansion is, indeed, tragically unmissable. He stands and stares at it for a minute, trying to fathom what the architect had been thinking. It is a busy piece of work, with an excessive number of gables. He can only suppose that the designer wanted to build what was really a large, single dwelling, but sought to camouflage it as a line of at least half a dozen wildly mismatched urban row-houses inexplicably crammed together in the middle of six hundred acres of Buckinghamshire farmland.

– Neal Stephenson, Cryptonomicon

As part of beckyc's birthday celebrations, I was part of a bunch of about ten people who went to the Bletchley Park museum yesterday. I'd never been there before, although I had of course read Enigma and Cryptonomicon so it was a familiar setting in my imagination if not in reality.

One of the major things I noticed on getting there was that the above quotation is all absolutely true. The crowning touch, I feel, is the gable and cupola which interpenetrate in a manner which suggests they were accidentally overlaid in a ray-tracing program by somebody who wasn't paying quite enough attention to their coordinates. It's a monstrosity, and that's coming from somebody who doesn't usually have enough interest in architecture to express any strong opinions about it at all.

As for the rest of the park, well, it was good, but somehow more museumy than I'd have hoped. As a museum it's definitely good – many of the display cases and information boards tell you genuinely interesting stuff – but somehow I felt that you could have set up a conventional glass-cases-and-posters museum about Bletchley Park anywhere you liked, and if you were going to do something on the site itself then you surely ought to make use of that in a more creative fashion, such as by trying to reconstruct the interiors of the huts in a way that actually gave an impression of what it might have been like to be involved in the codebreaking efforts. Hut 4, for example, should have been cramped, crowded, and full of filing cabinets and exasperated naval intelligence officers dashing back and forth with small slips of paper, or failing that at least given the impression that said officers had just popped out for an important meeting and would be very busy again as soon as they came back. Instead, it was a largely empty shell containing a lecture room.

I got into an argument with the tour guide at one point, over a technical point about the codebreaking procedure. I did some quick calculations using my watch's calculator mode to support my claims, but he said some of my assumptions were faulty. I went away and thought about that; it occurred to me that if I had a computer handy instead of a piffling little calculator then I ought to be able to knock together a real demonstration of my point pretty quickly. Then it occurred to me that the hands-on exhibits in the history-of-computing museum included a BBC micro, so I wandered over there and quickly typed in a twenty-line program which tested my assertion; the tour guide came back half an hour later while we were eating lunch and I was able to cite the results of that program as part of my argument :-) He eventually conceded my point after discovering that he'd misunderstood it. (Phew.)

It hadn't occurred to me, but clearly should have with hindsight, that Bletchley Park's visitors would be likely to contain a high proportion of geeks. While I was hacking on the Beeb, a random old guy came over to watch what I was doing, and then said in a slightly puzzled voice ‘You don't look old enough to know how to program a BBC’. This struck me as slightly odd, since I didn't even encounter a BBC until about seven years after starting to learn to program, by which time it wasn't about to present me with any conceptual difficulties; but I suppose if (as he did) you'd programmed the things yourself when you were forty, you might be slightly surprised that a teenager would have been doing the same things.

Still, a good day out all round. A tiring one, though, so it's a good job I have today to recover from it before going back to work!