Something I've always found annoying about the fixing of certain kinds of problem – particularly those around the house – is that it's very hard to take pleasure in having done it, because my brain quickly forgets the problem was ever there.

For instance, many years ago I lived in a house where the door handle kept falling off one of the kitchen cupboards. Every time I tried to use the cupboard, the handle would come off in my hand, and in order to get the cupboard open I'd have to reinsert it and then twist it at an angle so that the loose screw would apply friction to the inside of the screw hole. Eventually I lost my patience and filled the screw hole with superglue, and then it was fine.

In my ideal world, I would have liked this action to be followed by an active sense of satisfaction at a job well done every time I used the cupboard and didn't have to fiddle with the door handle. This ongoing sense of satisfaction ought properly, it seems to me, to have lasted for a length of time commensurate with the length of time for which I'd had to put up with the problem.

But in fact, in only a day or so I had almost completely forgotten the problem had ever existed. I think this is because I'd always been bad at remembering about it anyway: it was rare that I'd go to that cupboard and remember to twist the handle at the angle that made it not fall off, and more usually I'd pull the handle in the normal way, swear, put it back on and then try again more carefully. So I very quickly reached the point where I'd reflexively yank the door open as if its handle had always worked fine, and not think twice about it. So that sense of satisfaction at having fixed the problem was completely gone.

(None of my housemates commented on the door handle having started working either, which I guessed was for the same reason.)

Of course, that doesn't mean it wasn't worth fixing the problem. It had previously irritated me every time, and afterwards it didn't. Clearly that bit of work with superglue did improve my life. But it didn't feel as if it had made my life better, since to know your life is better you have to remember that it was previously worse.

There's a whole class of household (and other) irritations that have this same property for me: as long as they're unfixed, they annoy me, but as soon as they're fixed I forget about them too quickly to derive any real satisfaction. It's as if such problems find one last way, with their metaphorical dying breath, to annoy me again.

Newcomb's Cat: There's an opaque box containing a cat and some poison gas. There's also a transparent box, which you can see contains a live kitten. Depending on how you're about to decide, the poison gas might or might not have been released in the opaque box, and as a result you're in a superposition of states, mysteriously all of which involve cleaning up one sort of cat-related mess or another.

Pascal's Dilemma: There are two heretics imprisoned by the Inquisition, and they separately have to decide whether or not to recant and believe in God. The terms of the problem are set up so that it's invariably in each prisoner's selfish interest to believe in God, and yet for some reason they both turn out to decide it's all a load of rubbish.

The Chinese Demon: There's a room in which people are shuffling pieces of paper in the execution of a complex algorithm that answers questions in Chinese. However, the door to the room is guarded by an infinitesimal demon that only lets the most difficult questions through, and as a result the contents of the room become more and more disordered until nobody can find the pieces of paper they want any more.

(I accidentally invented one of these in the pub just now, and thought it was fun enough that I should add a couple more and post it.)

Privileged misinformation. Because you have inside knowledge of a situation, you're confident you understand it better than someone without that special knowledge. So you feel free to do things which would look utterly silly to that outsider, because you know why they're not such silly things to do after all, and the outsider doesn't.

Only, every so often, your inside knowledge turns out to be wrong. Then you have not only caused something bad to happen, but you've also made yourself look an utter fool to any watching outsiders. ‘I would have known,’ they think, ‘not to do that. What was he thinking?!’

If your inside knowledge had been right, then the results would have spoken for themselves: the outsider might have wondered what you were doing to start with, but when something obviously desirable happened in response, they would have understood that somehow you'd known it would and they hadn't. But if you try that and get it wrong, you'll never convince the watching outsiders that you weren't simply stupid.

If you're used to seeing an actor playing a particular character, it can be hard to put that character out of your mind when you see the same actor in a different role.

It's recently come to my attention that this goes at least triple if the character you're used to seeing them play is a master of disguise. Suddenly it doesn't even seem incongruous that they're not dressed the same way as usual!

I just got out of bed, and was slightly startled to find myself unshaven. That is of course the normal state in which I get out of bed, but this time it was surprising, because I was sure I could remember having done it already for some reason.

It was, of course, in one of my dreams.

I think that's the most irritating dream I've had in weeks. Shaving's an annoying chore at the best of times, and it seems particularly unfair to have done it already and still have to do it again. Bah!

‘A woman of wisdom,’ Brennan said, ‘once told me that it is wisest to regard our past selves as fools beyond redemption – to see the people we once were as idiots entire. I do not necessarily say this myself; but it is what she said to me, and there is more than a grain of truth in it. As long as we are making excuses for the past, trying to make it look better, respecting it, we cannot make a clean break.’

– http://www.overcomingbias.com/2008/05/eld-science.html

I stumbled across the above quotation the other day when chasing links from another blog, and it inspired me to get round to writing up something I've been thinking about for a while.

I can understand and agree with Brennan's observation that there is some truth in the quoted proposition; but where he says he doesn't ‘necessarily’ agree with it completely, I'd go further than that and say that I strongly disagree with it as a universal premise. One of the things I'm most pleased with about my own mind is my ability to trust my past self, when it's appropriate.

This typically occurs when you've previously given some thought to a situation, and decided – dispassionately, carefully, and in a calm and collected fashion – what would be the best thing to do in that situation. But suppose the nature of the situation is … I want to say ‘emotionally loud’, by which I mean that it evokes some sort of strong concentration-disrupting emotions, possibly conflicting ones, when you're in it for real. Now your emotions are screaming at you to do something other than what you previously thought you should do, or perhaps even several contradictory other things. Worse still, they corrupt and seduce your rational thought processes, so that the wrong courses of action are not merely emotionally desirable, but now even seem sensible to you because your brain has got into a state where it's wilfully forgotten all the reasons why they're not.

At this sort of moment, the only thing arguing in favour of your pre-prepared choice is the memory that it's what you decided when you were thinking straight. To let that small quiet voice of memory, shorn of all its supporting reasoning and arguments, overrule all the reasons why the other courses of action seem obviously right to you right now takes a certain measure of stubbornness, a certain measure of self-control, but even more than both it takes something that I tend to think of as self-trust to motivate you in the first place to exercise that self-control and stubbornness: one is trusting one's past self to know better than one's current self, and consciously abdicating the attempt to decide on a course of action in favour of letting it decide for you.

It's even more difficult if you haven't considered the exact situation before, but have merely thought about things distantly related to it and worked out some general and extremely vague principles of wisdom (of the general level of vagueness of, say, ‘don't overreach’). To act on one of those principles when your emotions have seduced your rational thought processes into being convinced that the details of the current situation render the principle inapplicable requires considerable self-trust.

I don't claim to be outstanding at displaying this quality. But I manage it on a reasonably regular basis, and it's one of the things that makes me feel most pleased with myself afterwards: when my head is once again clear I'm able to look back on what I did in the middle of the chaos, remember all the reasons why it really was the right thing to do, and take pride in having managed to do it in spite of having forgotten all those reasons at the time I made the choice.

Science fiction occasionally writes about super-rational beings – whether AIs, aliens, superevolved humans or merely highly trained actual humans – which are capable of making the right decision for the right reasons by means of having their reasoning processes actually be unaffected by emotional pressure (except in that they can note the existence of those emotions and dispassionately treat them as another datum to reason with). In the absence of that highly desirable but frankly unrealistic capability, I tend to think that self-trust of this nature is the closest we poor mortals can come to achieving the same effects. The sage Brennan quotes above would have us throw out, with the bathwater of closed-minded unwillingness to revise an entrenched but wrong opinion, that not inconsiderable baby.

Normally I don't mind being got out of bed by a parcel delivery. It may lose me half an hour of sleep, but I get cool stuff to compensate, and in particular it means I don't have to find my way to some random parcel-company depot in Bar Hill a day or two later to get my cool stuff.

However, when the parcel turns out to contain the wrong item, I think I'm justified in being annoyed. I want my half hour of sleep back! (And my cool stuff, this time in the UK version.)

ThinkGeek has sold, for many years, a T-shirt reading ‘Go away or I will replace you with a very small shell script’.

I've said a number of times to friends, but never got round to actually writing down anywhere, that I've always thought that shirt would be improved by a backprint reading:

#!/bin/bash
case $((RANDOM % 3)) in
  0) echo "What?" ;;
  1) echo "I don't understand." ;;
  2) echo "Where's the tea?" ;;
esac

It just occurred to me this morning to wonder if ThinkGeek might like to hear that idea themselves. I looked around their website, and found they have a web form for submitting T-shirt ideas – and will even pay you if they use yours. Aha!

… not aha. It turns out that the terms and conditions for that programme require you to certify that you're in the USA or Canada. Apparently nobody anywhere else is capable of having worthwhile ideas.

It's common in problem-solving disciplines to find that once a problem is correctly stated, the solution can often become obvious.

On which basis: the trouble with snow is that it's white, cold, solid, and contains no caffeine.

He took his vorpal sword in hand;
Long time the manxome foe he sought…

It's just occurred to me to wonder: did the protagonist of ‘Jabberwocky’ perhaps take a few chocolate bars with him for sustenance during his long search?

He might well, after all, have anticipated the need for a Snickers snack.

eta: I forgot to say so specifically, but I hope the people who have ticked "something else interesting" will say what it was :-)

It's nice to hear that pretty much everybody else seems to have had a good Christmas. I, unfortunately, did not have a good Christmas, because I've spent most of this week basically incapacitated by flu.

So my Christmas Day largely involved me sitting on the sofa watching DVDs I'd seen before and trying not to move too much. The original plan had been that Mum would come to visit and I'd cook her a big Christmas roast dinner; instead, she came round and cooked me a small and inoffensive omelette, which was about all my beleaguered metabolism could cope with.

That made yesterday the first Christmas Day in my whole life (at least since I was old enough to remember them at all) which didn't involve some sort of appropriately Christmassy celebration. I feel surprisingly unhappy about that. It's not that anything's actually been lost, as such – Mum and I plan to have a postponed celebration at some later point once I'm well. And it's not even as if I've gone without Christmas dinner so far this year: I cooked an early one for Dad a week ago, and the Gallery did its usual excellent one the week before that. But, somehow, it isn't the same.

Turns out they hadn't taken it away permanently; they were just replacing it with a newer (and, mysteriously, smaller and uglier) model. How silly.

You know you're in serious trouble, in programming, when you find you need to use the word ‘ontology’ in a technical discussion.

I've been running my personal alarm clock program on my Chumby for over seven months now, and this is the first morning on which it's occurred to me that it might have been a bad idea for the ‘SNOOZE’ and ‘SHUT UP’ buttons on the touch-screen to be the same size, shape and colour and to have legends starting with the same letter.

I thought I'd hit Snooze this morning, and had certainly meant to hit Snooze, but the next thing I knew I was waking up half an hour later and going to be late for work, so apparently I hit shut-up instead. Some redesign required.

This morning I was woken from a dream by my alarm clock, right in the middle of the bit of the dream that made the least possible sense. Under the influence of the resulting sense of confusion I got into the shower, washed myself, realised I hadn't used nearly enough shower gel and had to wash myself again. Then I pulled the shower curtain rail down in a fit of total incompetence.

When you realise it's one of those days before you've even got dressed, it's going to be a bad one.

Just now I went to the company kitchen for coffee, and dropped a corporate mug on the floor, breaking it in half. It broke beautifully: a single straight break in a vertical plane, dividing the half with the handle from the half opposite the handle with an absolute minimum of small shrapnel. If I had my camera here I'd have taken a picture, that's how prettily it broke. Unfortunately, it didn't do anything to dispel the sense of it being one of those days.

Last Sunday evening – that is, about eight and a half days ago – I was out in the street on foot, and I walked around the back of a large van parked by the roadside. I found out slightly too late and the hard way that the van had a tailboard sticking a foot out of the back at mid-shin height, which was almost invisible in the shadows. So I did the obvious thing: hopped up and down for a couple of minutes clutching my shin and cursing, then went on my way.

Since then my shin has given the occasional mild twinge in the place where I hit it, but it's looked undamaged, and not actually inconvenienced me. I had expected it to get completely better soon.

I am therefore somewhat startled, over a week later, to find that my shin has now, fairly suddenly, developed a visible bruise and become inconveniently tender to the touch. Bodies make no sense!

Yesterday I got a travel brochure through the door addressed to a previous occupant. So I stuck a ‘return to sender’ label on it, and left it by the front door to repost the next time I went out. Today I left the house to go to work; I picked up the brochure on the way, and walked four houses down the street to the incredibly convenient nearby postbox.

Or rather, to where the postbox used to be. It's vanished, with not even an obvious scar where it was uprooted. I stood and stared at the empty space for a couple of minutes, unable to believe I hadn't just made a silly mistake of some sort.

Bah! Suddenly the niceness of the location of my house has gone down. Not that the convenient postbox contributed at all to my purchase decision – I didn't even notice it was there until after completion – but I've been finding it thoroughly useful while it was there, and now they've taken it away. Humph.

(So now I need to find my next nearest postbox. A quick google turns up four or five websites which purport to be able to show me a map of where all the nearest postboxes are to a given location; but they're all rubbish as far as I can tell, and in particular they all have incomplete data.)

The Tesco near work has recently been teching-up the price labels attached to its shelves. In several aisles, the old-fashioned pieces of paper with product details and price printed on them have been replaced with little electronic gizmos with LCDs of comparable size, and the same product and price information is displayed on those.

I have to assume the useful feature of this system is that they can update the prices at the touch of a button from their lair central control room; they can introduce special offers, rescind special offers, or just keep prices generally in line with the current economic conditions without having to send a henchman stock control operative out in person to physically replace lots of labels.

I am therefore at a loss to explain why they have two different types of gizmo, one with a beige case for normal prices and one with a red case for special offers. Surely this precisely defeats the purpose – now they have to send someone round to replace the gizmos again whenever they want to start or stop a special offer!

When you compile a source file and get multiple compile errors, there are two conflicting principles governing the order in which you go through the source file fixing them.

On the one hand, you want to fix the errors from the top downwards, because of the possibility that some errors are cascades from others: fixing earlier errors may cause later ones to turn into non-errors or shed light on what the problem really was.

On the other hand, if you fix an early error in a way that changes the number of lines in the source file, then you have to mentally adjust all the line numbers in the subsequent error messages. Do this multiple times and you're looking at keeping a running track of the cumulative change to the file's line count as you edit, which you didn't really want to have to hold in your head at the same time as the more important state regarding the problems you're fixing.

The solution is simple. Line numbers in source files should be indexed backwards from the end, with line 0 being the part of the file after the final newline, line 1 the line before that, and so on. If compilers reported errors using those line numbers, and programmers' text editors displayed the same line numbers, then there would no longer be a conflict: you'd fix compile errors from the top of the file downwards, each error message would have a correct line number when you reached it, and you'd only see cascade errors after fixing the primary error that caused them.