Bike light design

Sep. 20th, 2017 08:12 pm
jack: (Default)
[personal profile] jack
For a while I had the impression my back bike light remembered whether it was on or not when you removed and replaced the battery. And I wondered how that worked. A push-button that moved a physical toggle between three positions seemed implausible. But so did some tiny bit of persistent memory. My best guess is that there was a capacitor which held charge for a short time.

Now, I think I was completely wrong. I think that when you put the battery in, it *always* comes on. I just assumed that it would usually be off and didn't actually check that was true. So I got the impression it was lit *sometimes* on battery-connect, and connected that to the state it had before the battery was removed.

Wow, it's really easy to manufacture evidence for something even when you think you're avoiding that.

Presumably the "power on lit" is so that loose connections don't turn it off. OTOH, that would mean if it has a loose connection when it's being carried about, it might come on and drain the battery. Or maybe no-one thought about it and this just happened to be the case. Or maybe there's a regulation? I don't know.

English usage

Sep. 18th, 2017 07:24 pm
damerell: NetHack. (Default)
[personal profile] damerell
Note: food eaten between supper and breakfast is incorrectly referred to as a midnight snack. The correct term is "dark lunch".
jack: (Default)
[personal profile] jack
Removing code is good! But everywhere I've worked has had a "pile of makefiles" build system, which have invariably had problems when you remove a file, because the .d files are still hanging around, and make chokes on a source file because it doesn't have the headers it needed last time, even though they're actually not necessary to actually build the file.

And it's a matter of culture whether it's "when you check out code, you often need to make clean or make undepend somewhere to get it to compile" or "when you check in code, you need to find a workaround to make it build cleanly even if you've removed files".

Do people with more recent build tools than "make" avoid this problem?

However, after thinking it through carefully I eventually decided on one of the ways to makefiles cope with this correctly.

The trick

You still do "-include $(OBJ_FILES:%.c=%.d)" or equivalent.

But when you produce a .d file with gcc (usually as a side effect of producing a .o file via -MMD), add an extra line at the end of the recipe, a perl script which edits the .d file in-place and replaces each "filename.o: header1.h header2.h..." with "filename.o $(wildcard: header1.h header2.h...)"

That way, if any dependency has *changed* a rebuild is forced as normal. But only dependencies that actually exist become dependencies within the makefile. (Deleting a header file doesn't trigger a rebuild, but it doesn't with the old system either since the .o file already exists.)

I can share the exact script if anyone wants to see.

Yuletide nominations

Sep. 14th, 2017 10:40 pm
jack: (Default)
[personal profile] jack
I nominated for Yuletide. After lots of "how could I possibly choose", I decided that I might as well pick three works I liked and thought would make good fic, and not feel like I had to pick the BEST three. I can probably dredge up more obscure things I loved, and would really love to see fic from, but I find it hard to bring to mind things I've not thought of for ages.

There's lots of things I love, things like webcomics and webfiction which might deserve attention. I eventually chose three I thought would make good stories.

Elements (experiments in character design), the tarot-like cards showing a character for each chemical element. They're just so pretty, each looks like it tells a story. I was sad the physical cards seemed to be sold out and never for sale. They were nominated two years ago, and I was sad to see not last year.

And two webcomics, Leftover Soup (from Tailsteak, the author of the awesome 1/0, ooh, maybe I should submit that instead), and YAFGC (Yet Another Fantasy Gamer Comic, like Oglaf, very not safe for work, but sort of in a surprisingly wholesome way).

Did other people manage to nominate things?

I am also basking in the disconcertingly competent assumption that, I expect to be able to, just get a story done, without a whole lot of putting it off. I'm not at all used to signing up to something with a deadline and not assuming I'll panic but it's worth it!

I looked at my notes from last year for "what might I be interested in nominating next year". It was mostly the same sorts of things. Although one was, "Steven Universe, if it doesn't exceed the limit of number of works", I guess that must have happened now :) Although I find it really hard to predict. I went to look up Vorkosigan, the universe I was surprised was still eligible when I wrote for it two years ago, and it looks like there's more than a 1000 fics on ao3 from before that, am I misremembering how eligibility/search works?


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