maradydd: (Default)
Dear LJ Genie,

I am thinking about spending some quality time with Scala. What would you recommend, resource-wise, for a Java expert (I taught it for two years) with a reasonable amount of functional programming experience? I've looked over a bunch of the references on the Scala website, and they make good sense; what I'm particularly looking for are resources of the sort that make lightbulbs go off in one's head.

maradydd: (Default)
Dear LJ Genie,

I need to have two boxes, one 19 pounds and the other 23 pounds, shipped from Portland to Belgium. Each box is 24" x 24" x 24". Apparently the sizes of the boxes put them into some horrible no-man's-land whereby costs are computed by "volume weight" rather than actual weight -- apparently I could ship 83 pounds worth of stuff for the same price. For the prices that I am being quoted, I could buy one of you Portlanders a ticket to Belgium and have the Portlander in question bring the boxes in lieu of checked luggage. While this idea amuses me enormously, I do not currently have a spare $700 to do this with -- or to ship boxes, natuerlich.

The boxes can arrive pretty much anytime prior to the heat death of the universe (well, okay, sometime this year would be nice), and they'll be full of (well-packed) glass and thus can't be banged around too horribly, but other than that, my main concern is getting them here on the cheap.

maradydd: (Default)
Dear LJ Genie,

What's the best way to hang a pegboard on an exposed (indoor) brick wall?
maradydd: (Default)
Has anyone reading this used Scrapy, the Python HTML-scraping framework, programmatically as part of a larger system? I'm interested in using it to replace BeautifulSoup in a project I'm working on which involves extracting specific, XPath-targetable tags from the contents of a whole bunch of different URLs. BeautifulSoup can do it, but the CPU and memory load is really heavy and I'd like to find a lighter-weight solution. (Scrapy supports XPath out of the box, which was a great design decision on their part.)

The specific problem I'm having with Scrapy is that despite the fact that it supports writing custom scrapers, it's designed as a command-line-driven tool to the exclusion of anything else. I want to instantiate a scraper from within a routine, run it, and hand the contents of the tags it collects off to another routine all within the same process, without having to invoke a separate process or touch the disk -- this system has to consume a lot of network data and I can't afford for it to become I/O bound. (I can queue the inbound network data -- in fact, since my current architecture is completely synchronous, I already am -- but not having to do so is preferable. Scrapy is asynchronous and that's a plus.)

Since it's written in Python, I can trace the control flow and figure out what specific pieces I need to import and/or customise to get it to do what I want, but it's a pretty densely layered system and it would be nice to have some examples to use for guidance. The documentation is unfortunately useless in this regard -- all the examples are for command-line invocation -- and neither Google Code Search nor turn up anything useful.

N.B.: I'm reluctant to just use libxml2, because most of the pages I'm scraping are not XHTML-compliant. In fact, a surprisingly large number of them have HTML so malformed that BeautifulSoup chokes on them and I have to use an exponential-backoff approach to parse only a piece of the document at a time. (And in practice, that means I sometimes lose data anyway; this is annoying, but frustratingly necessary. Dear web developers who cannot be bothered to make their content machine-readable without lots of massaging: die in a fire.) It is my understanding that Scrapy is quite tolerant of bad markup, but if I'm wrong about that, please correct me.
maradydd: (Default)
Dear LJ Genie,

Here is a picture of an audio cable:

an audio cable

I know that I can go to Radio Shack and buy a screw-together or snap-together end for an audio cable, but the friend on whose behalf I am asking doesn't need an audio cable; he needs to provide more mechanical stability for a join, and layered heat-shrink tubing doesn't look nice. Is there a name for the thick plastic part of the cable that one holds onto while inserting the male end into a socket, such that I could search for it on digi-key?

ETA: It's a strain relief boot. Thanks, [ profile] grepmaster and [ profile] tikiking!
maradydd: (Default)
Anyone in the bay area got a spare GSM phone (unlocked, or locked to T-Mobile) they're not using and want to get rid of / are willing to loan for a week or three?

Lemme know.
maradydd: (Default)
Dear LJ Genie,

Thanks for all the great advice about accelerometers and uCs! I've now got a line on a local electronics supplier (walking distance, for long values of walking) and will be visiting there soon. Now for a research question -- I don't think I'll be following up on this anytime soon, but it'll help to have my eyes open.

What's a good, affordable, entry-level FPGA for a reasonably competent programmer who can already build arbitrary logic gates from transistors, but doesn't have a lot of other fundamentals down yet? (I do not, for instance, have all that great of a grasp of the intricacies involved in CPU design -- tradeoffs, pitfalls, that kind of thing. Okay, any grasp, really. But I'd like to learn, and have some suitably horrifying ideas about defining something that resembles a fitness function for a processor and doing awful, awful things with Verilog and code generation...)

Alternately, is there a software-based FPGA simulator/emulator that's worth a damn?
maradydd: (Default)
Oh mighty LJ Genie: what is the physically smallest one-axis accelerometer I can source? (Preferably one that also has a development version available in DIP so that I don't have to jack around with breakout boards. I am willing to hand solder up to QFP .5mm pitch.)

Also needed: tiny 8-bit microcontroller. SOaCs with integral accelerometer acceptable if they're smaller than the amount of space required for an accelerometer and micro together. AVR preferred, Freescale completely acceptable, will learn PIC if required.

ETA: yes, I will be outsourcing fabrication, but would like to prototype on larger-scale equivalents, kthx
maradydd: (Default)
I'm building a C++ project for an unusual platform, and am having some confusing problems with my libstdc++. For some reason which I cannot fathom, I am getting an absurd number of "undefined reference to..." linker errors for symbols which are indeed undefined in libstdc++.a, but which are definitely defined in libc.a and libgcc.a. Yes, I am linking to both of those. (I know I am, because earlier I was getting some undefined-reference errors to symbols in libgcc.a from the code I'm actually compiling, and when I added -lgcc they went away.)

Any idea what's going on here? Do I need to compile libstdc++ from scratch rather than using the provided binary? (Please, God, let the answer to that be "no".)

ETA: enigmatic ld ordering issues for the lose. Thanks, [ profile] tangaroa!
maradydd: (Default)
A dear friend is thinking about going to grad school (could be an MS, could be a PhD, depends on what they'll let him get away with), focusing on database internals (the query planner and executor, to be precise). Aside from "Tom Lane's office", anybody got any tips on places he should be considering? He has a bachelor's in CS from McGill and several years of solid industry experience; I figure he should be a shoo-in for a top program. However, I do not know what the top programs are.

[ profile] jrtom, you were saying good things about UC Irvine, weren't you? I know Berkeley has some interesting work going on with streaming databases, but is that just something they specialise in, or do they have a solid database-backend team?


maradydd: (Default)

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