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Comment Re:Grand Central Dispatch (Score 2, Interesting) 219

Porting libdispatch requires a generic event delivery framework, where the userspace process can wait for a variety of different types of event (signals, I/O, timers). ... Linux is the odd system out. All different types of kernel events are delivered to userspace via different mechanisms, so it's really hairy trying to block waiting until the next kernel event.

I don't understand this. It's true Linux does not have kqueue. (as I recall Linus thought it was "ugly" ... whatever) But in theory (because I haven't actually used them), to achieve the same effect under Linux, you would use timerfd() + signalfd() + (your normal i/o fds like sockets etc.) ... and then epoll_wait()/poll()/select() on all of the fds you were interested in. In this way, one thread could wait for multiple different types of events, including timers and signals.

Would you please point out the flaws w/the above that make it impossible or impractical to achieve the functionality needed by Grand Dispatch? I would be enlightened -- thanks in advance.

Comment Re:HAH! (Score 1) 387

I did run iBCS, and while it seemed to work well for what it did, it is not a panacea for everything.

For example, anything that was dynamically linked would still have dependencies on the original system libraries. So you get to copy all those over, worry about licensing issues (if you're trying to redistribute, anyway), and hope something didn't break on the way. In my experience, a c++ widget-generating app we were trying to run encountered both of those roadblocks, and we determined it was better to go another route -- java, hah!

Medicine

Wii Balance Board Gives $18,000 Medical Device a Run For Its Money 422

Gizmodo highlights a very cool repurposing effort for the Wii's Balance Board accessory. Rather than the specialized force platforms used to quantify patients' ability to balance after a trauma like stroke, doctors at the University of Melbourne thought that a Balance Board might serve as well. Says the article: "When doctors disassembled the board, they found the accelerometers and strain gauges to be of 'excellent' quality. 'I was shocked given the price: it was an extremely impressive strain gauge set-up.'" Games controllers you'd expect to be durable and at least fairly accurate; what's surprising is just how much comparable, purpose-built devices cost. In this case, the Balance Board (just under $100) was compared favorably with a test platform that costs just a shade less than $18,000.

Comment Re:Put the onus on financial institutions (Score 1) 168

You can lend friends money. Just not money you would mind losing. It's like gambling basically.

Side note: I once loaned a small amount of money to an annoying "friend" who then apparently fell off the face of the earth. It was worth the money. Although I suppose I could have achieved the same effect by just being a d*ck about his sob story, but that eats at your conscience a little more.

Comment Re:Concurrency? (Score 1) 173

Though I imagine the problem for larger computations could be that you're limited to writing functional-style code, at which point you might be better off using a language designed for it?

Point taken, assuming it has to be fast and there is that much critical code.

What optimizations does gcc actually do on pure functions, having identified them?

Well, it doesn't dispatch them :-) from what I read in the documents, all it might do now is common subexpression elimination.

Image

Magento Beginner's Guide Screenshot-sm 124

Michael J. Ross writes "The shopping cart systems that power online stores have evolved from simple homebrew solutions in the CGI era to far more powerful open source packages, such as osCommerce. But even the later systems are frequently criticized as suffering from poorly-written code and inadequate documentation — as well as for being difficult to install and administer, and nearly impossible to enhance with new functionality and improved site styling, at least without hiring outside help. These problems alone would explain the rapidly growing interest in the latest generation of shopping cart systems, such as Magento, purported to be outpacing all others in adoption. In turn, technical publishers are making available books to help developers and site owners get started with this e-commerce alternative, such as Magento: Beginner's Guide, written by William Rice." Read on for the rest of Michael's review.

Comment Re:Concurrency? (Score 1) 173

they have no mutable variables in the usual sense ... You can't do this in C or Java because it might be necessary for one function to see a variable modified by another.

I think the key word here is "might".

Nothing prevents a C compiler from figuring out "int foo(int a) { return a + 2; }" is pure. In fact gcc can do this to some extent; the relevant compiler flag (enabled by default w/optimization) is "-fipa-pure-const".

gcc also lets you specify the attribute 'const' to declare that a function is pure (in the sense that we're using it here).

Sure, it's coarse, and an afterthought, but it's also flexible.

Comment Re:It's their own fault (Score 2, Interesting) 420

Well, maybe both.

Yes I probably wouldn't enjoy being on a site that went on and on about "Windows Rocks/Linux Sucks" (as much as this site does the reverse, anyway).

But that kind of rhetoric is not really why I read this site. As an example, I found the (apparently) 1st-person accounts about air traffic and ATC procedures yesterday to be one of the most informative and entertaining bits I've read in awhile.

Slashdot has (more than?) its fair share of trolls, and troll articles, but there is (sometimes) a depth here that I haven't really found anywhere else yet; and that includes your local newspaper.

Robotics

Robot Controlled By Human Brain Cells 86

destinyland writes "There's a new experiment from the British researchers who created a robot controlled by cultured rat neurons. They're now using a line of human brain neurons to control robots. The neurons are placed onto a multi-electrode dish that registers the neurons' electric signals. 'Every time the robot nears an object, the electrodes generate signals to stimulate the brain. In response, the brain's output is used to drive the wheels of the robot left and right so that it avoids hitting objects. The robot has no additional control from a human or a computer — its sole means of control is from its own brain.'"

Comment Re:Version Control Systems all have one thing (Score 1) 268

I used ClearCase at my previous job, and the mode of use you mentioned, while interesting (files could change in your source tree as others checked in code, I believe), was impractical for me. Building out of one of those directories was like building out of an NFS-mounted directory ... an order of magnitude slower, too slow to be usable.

ClearCase also supported the typical 'check your workspace ("view"?) out to a local place on your hard drive, rebase it occasionally, make your changes, and check it in' model, and that seemed to work fine.

And yes we had a full-time administrator for the system. Would've been suicide not to.

Comment Re:And if you don't like marshmallows? (Score 1) 105

Well, let's pretend for a moment that the scientists didn't take that into account. If I didn't like something I might actually eat it just to get the experiment over with so I could get out of there and go play with some toys or something. I might hold out for a marshmellow, they're so-so. But if, for example, you gave me a peppermint (which I don't like) ... I would probably give it a "what is the point" look and then eat it.

I mean, the reward for waiting actually needs to be worth something.

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