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• Ruby Summer of Code Project Ideas

  - by blatyo

  So, I'm thinking about applying for Ruby Summer of Code. However, I'm not sure what I want to propose. I was wondering if any of my fellow redditors had any good ideas? I've been programming in Ruby for about 3 years. I am primarily a web developer, but I do things related to bit torrent, data mining, and databases as well. I have a bit torrent related gem that I wrote for the hell of it. I've also got some projects on Github (username: blatyo). I am looking for ideas for me, but anything you can think of that would be awesome I would like to hear as well.

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• Determining default character set of platform in Java

  - by Anand

  I am programming in Java I have the code as: byte[] b = test.getBytes(); In the api it is specified that if we do not specify character encoding it takes the default platform character encoding. What is meant by "default platform character encoding" ? Does it mean the Java encoding or the OS encoding ? If it means OS encoding the how can i check the default character encoding of Windows and Linux ? Is there anyway we can get the default character encoding using command line ?

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• Seeking enlightenment - global variables in AppEngine (aeoid.get_current_user())

  - by jerd

  Hello This may be a 'Python Web Programming 101' question, but I'm confused about some code in the aeoid project (http://github.com/Arachnid/aeoid). here's the code: _current_user = None def get_current_user(): """Returns the currently logged in user, or None if no user is logged in.""" global _current_user if not _current_user and 'aeoid.user' in os.environ: _current_user = User(None, _from_model_key=os.environ['aeoid.user']) return _current_user But my understanding was that global variables were, ehm, global! And so different requests from different users could (potentially) access and update the same value, hence the need for sessions, in order to store per-user, non-global variables. So, in the code above, what prevents one request from believing the current user is the user set by another request? Sorry if this is basic, it's just not how i thought things worked. Thanks

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• Error Domain=SKErrorDomain Code=3 UserInfo=0x2a5a00 "Cannot connect to iTunes Store"

  - by SKk

  I am trying to implement InApp purchase in my application. I have implemented it as per Apple's programming guide and it(code) was working fine until I created new application, appid, provisioning profile and in-app products @ another developer account. Now, it gives me following error. Error Domain=SKErrorDomain Code=3 UserInfo=0x2a5a00 "Cannot connect to iTunes Store" Same code works fine if I use previous developer account's appid, pro-certificate and product ids. This is very strange issue, I double checked product id names and other things still facing same error. Any clue..?

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• iPhone Bluetooth application to connect to a Bluetooth printer

  - by Vijayanand

  Hi, Has anybody succeeded in developing a bluetooth application on the iPhone that prints to a Bluetooth printer? I have been investigating the feasibility of developing an iPhone application that could print to a Bluetooth-enabled printer. I've gone through the most of the postings in this thread and was confused by the mail exchanges. As per my analysis: Gamekit - can be used for bluetooth connectivity between iPhones and IPods ONLY Bonjour - can be used for wi-fi connectivity between iPhones/IPods and bonjour-enabled printer We can use an external accessory to connect to a third party Bluetooth-enabled printer provided the 3rd-party printer complies with the necessary regulations from Apple (registering for either “Made for iPod”/ “Works with iPhone”, and also customizing their printer with specific hardware/software, etc.) Could someone please share their experiences?

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• How can I listen to multiple Serial Ports asynchronously in C#

  - by Kamiel Wanrooij

  I have an application that listens to a piece of hardware on a USB to Serial converter. My application should monitor more than one serial port at the same time. I loop the serial ports I need to listen to, and create a thread for each port. In the thread I have my data handing routine. When I assign one port, it runs flawlessly. When I listen to the other one, it also works. When I open both ports however, the second port always throws an UnauthorizedAccessException when calling serialPort.Open(). It does not matter in what order I open the ports, the second one always fails. I listen to the ports using serialPort.ReadLine() in a while loop. Can .NET open more than one port at the same time? Can I listen to both? Or should I use another (thread safe?) way to access my serial port events?

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• Android installation in a mobile

  - by Sundar

  Is it possible to install Android in a normal mobile phone? I have Sony Ericsson Naite which has only key pad interface (No touch). I would like to install Android in my phone for experimenting with it. It will be great if its possible to dual boot Android with Symbian :-). Do we need any other special hardware to install operating system in a mobile phone? Will Android work on a key-pad mobile? Any pointer/suggestion is appreciated. Thank you in advance.

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• Server Security

  - by mahatmanich

  I want to run my own root server (directly accessible from the web without a hardware firewall) with debian lenny, apache2, php5, mysql, postfix MTA, sftp (based on ssh) and maybe dns server. What measures/software would you recomend, and why, to secure this server down and minimalize the attack vector? Webapplications aside ... This is what I have so far: iptables (for gen. packet filtering) fail2ban (brute force attack defense) ssh (chang default, port disable root access) modsecurity - is really clumsy and a pain (any alternative here?) ?Sudo why should I use it? what is the advantage to normal user handling thinking about greensql for mysql www.greensql.net is tripwire worth looking at? snort? What am I missing? What is hot and what is not? Best practices? I like "KISS" - Keep it simple secure, I know it would be nice! Thanks in advance ...

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• Perl for a Python programmer

  - by fortran

  I know Python (and a bunch of other languages) and I think it might be nice to learn Perl, even if it seems that most of the people is doing it the other way around... My main concern is not about the language itself (I think that part is always easy), but about learning the Perlish (as contrasted with Pythonic) way of doing things; because I don't think it'll be worth the effort if I end up programming Python in Perl. So my questions are basically two: Are there many problems/application areas where it's actually more convenient to solve them in Perl rather than in Python? If the first question is positive, where can I found a good place to get started and learn best practices that is not oriented to beginners?

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• The Zen of Python distils the guiding principles for Python into 20 aphorisms but lists only 19. What's the twentieth?

  - by Jeff Walden

  From PEP 20, The Zen of Python: Long time Pythoneer Tim Peters succinctly channels the BDFL's guiding principles for Python's design into 20 aphorisms, only 19 of which have been written down. What is this twentieth aphorism? Does it exist, or is the reference merely a rhetorical device to make the reader think? (One potential answer that occurs to me is that "You aren't going to need it" is the remaining aphorism. If that were the case, it would both exist and act to make the reader think, and it would be characteristically playful, thus fitting the list all the better. But web searches suggest this to be an extreme programming mantra, not intrinsically Pythonic wisdom, so I'm stumped.)

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• tcp checksum and tcp offloading

  - by scatman

  i am using raw sockets to create my own socket. i need to set the tcp_checksum. i have tried a lot of references but all are not working (i am using wireshark for testing). could you help me please. by the way, i read somewhere that if you set tcp_checksum=0. then the hardware will calculate the checksum automatically for you. is this true? i tried it, but in wireshark the tcp_checksum gives a value of 0X000 and says tcp offload. i also read about tcp offloading, and didn't understand, is it only that wireshark is cannot check an offloaded tcp checksum, but there is a correct one??

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• glTexImage2D behavior on iPhone and other OpenGL ES platforms

  - by spurserh

  Hello, I am doing some work which involves drawing video frames in real time in OpenGL ES. Right now I am using glTexImage2D to transfer the data, in the absence of Pixel Buffer Objects and the like. I suspect that the use of glTexImage2D with one or two frames of look-ahead, that is, using several textures so that the glTexImage2D call can be initiated a frame or two ahead, will allow for sufficient parallelism to play in real time if the system is capable of it at all. Is my assumption true that the driver will handle the actual data transfer to the hardware asynchronously after glTexImage2D returns, assuming I don't try to use the texture or call glFinish/glFlush? Is there a better way to do this with OpenGL ES? Thank you very much, Sean

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• Email sent by ActionMailer is taking six hours to deliver mail.

  - by grg-n-sox

  So I have been asked to help maintain a website that uses Ruby on Rails. Now, let me just say I've been programming Ruby for awhile but I am still new to Rails. The first problem brought to my attention is how the activation email takes about six hours to arrive. It would be one thing if the email was not being sent due to errors but it is being send correctly, just slow. Also the server this is running on is also its own SMTP. I checked how the email was being formatted before calling the setup_email method and everything looks okay. I even dug into the ActionMailer lib and read through the files there and didn't see anything out of the ordinary. So what is most likely causing the email to take six hours to deliver?

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• Create a permalink with Javascript

  - by Jon Romero

  I have a textbox where a user puts a string like this: "hello world! I think that __i__ am awesome (yes I am!)" I need to create a correct url like this: hello-world-i-think-that-i-am-awesome-yes-i-am How can be done using reg expressions? Also, is it possible to do it with Greek (for example)? "Ge?a s?? ??sµe" turns to geia-sou-kosme In other programming languages (python/ruby) I am using a translation array. Should I do the same here?

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• append a numpy array to a numpy array

  - by Fraz

  I just started programming in python and am very new to numpy packages.. so still trying to get a hang of it. I have a an numpy_array so something like [ a b c] And then I want to append it into anotehr numpyarray (Just like we create a list of lists) How do we create an array of numpy arrays containing numpy arrays I tried to do the following without any luck >>> M = np.array([]) >>> M array([], dtype=float64) >>> M.append(a,axis=0) Traceback (most recent call last): File "<stdin>", line 1, in <module> AttributeError: 'numpy.ndarray' object has no attribute 'append' >>> a array([1, 2, 3])

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• Looking for calculator source code, BSD-licensed

  - by Horace Ho

  I have an urgent project which need many functions of a calculator (plus a few in-house business rule formulas). As I won't have time to re-invent the wheel so I am looking for source code directly. Requirements: BSD licensed (GPL won't help) in c/c++ programming language 32-bit CPU minimum dependency on platform API/data structure best with both RPN and prefix notation supported emulator/simulator code also acceptable (if not impossible to add custom formula) with following functions (from wikipedia) Scientific notation for calculating large numbers floating point arithmetic logarithmic functions, using both base 10 and base e trigonometry functions (some including hyperbolic trigonometry) exponents and roots beyond the square root quick access to constants such as pi and e plus hexadecimal, binary, and octal calculations, including basic Boolean math fractions optional statistics and probability calculations complex numbers programmability equation solving

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• Roadblocks in creating a custom operating system

  - by Dinah

  It seems to me that the most common overly ambitious project that programmers (esp. Comp. Sci. grads) try to tackle is building your own operating system. (Trying to create your own programming language + compiler is probably even more common but not nearly as ambitious.) For those (like myself) foolish enough to try: aside from the sheer size, what are the biggest *gotcha*s or unexpected roadblocks you've encountered in trying to create your own OS from the ground up? Edit: A great OS question: http://stackoverflow.com/questions/43180/how-to-get-started-in-operating-system-development/

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• Asynchronous operations performance

  - by LicenseQ

  One of the features of asynchronous programming in .NET is saving threads during long running operation execution. The FileStream class can be setup to allow asynchronous operations, that allows running (e.g.) a copy operation without virtually using any threads. To my surprise, I found that running asynchronous stream copy performs not only slower, but also uses more processing power than synchronous stream copy equivalent. Is there any benchmark tests were done to compare a synchronous vs asynchronous operation execution (file, network, etc.)? Does it really make sense to perform an asynchronous operation instead of spanning separate thread and perform synchronous operation in server environment if the asynchronous operation is times slower than the synchronous one?

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• Clojure editor/IDE recommendations on OS X

  - by Julien Chastang

  I am starting to learn the Clojure programming language. Are there any recommendations for Clojure editors/IDEs on OS X? Update 2009-9-23: The clojure space has changed tremendously since I originally posted this question. Many of the links below, especially those that refer to clojure-mode with emacs, are out-of-date. The best clojure IDE I found was the enclojure Netbeans plugin which was recently released (2009-08-25). Update 2010-4-30: Here is another very good link on this subject by Lau B. Jensen. Also, for my own clojure development, I have actually moved to emacs / swank-clojure.

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• A strong case for WF

  - by Pita.O

  Hi guys, I have struggled for so long to find a compelling use case for workflow (ie: WF) as against regular imperative programming. Each time I fall back to the conclusion that I should just leave WF out or defer getting into it until later. But I keep having this nagging feeling that there's something am missing. Does anyone know any book that truly makes a strong case for the Workflow way? The book has to (i) teach WF well, and (ii) show using appropriate use cases that WF made an implementation easy to do than if we just did our regular straight coding. I will appreciate it.

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• String Formatting Tricks/Docs

  - by Meltemi

  Was reading the response by Shaggy Frog to this post and was intrigued by the following line of code: NSLog(@"%@", [NSString stringWithFormat:@"%@:%*s%5.2f", key, padding, " ", [object floatValue]]); I know string formatting is an age old art but I'm kinda doing the end around into Cocoa/Obj-C programming and skipped a few grades along the way. Where is a good (best) place to learn all the string formatting tricks allowed in NSString's stringWithFormat? I'm familiar with Apple's String Format Specifiers page but from what I can tell it doesn't shed light on whatever is happening with %*s or the %5.2f (not to mention the 3 apparent placeholders followed by 4 arguments) above?!?

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• Language Design: Combining Gotos and Functions

  - by sub

  I'm designing and currently rethinking a low-level interpreted programming language with similarities to assembler. I very soon came across the functions/loops/gotos decision problem and thought that while loops like while and for would be too high-level and unfitting, gotos would be too low level, unmaintainable and generally evil again. Functions like you know them from most languages that have return values and arguments aren't fitting in the language's concept either. So I tried to figure out something between a function and a goto which is capable of Recursion Efficient loops After some thinking I came up with the idea of subroutines: They have a beginning and an end like a function They have a name but no arguments like a goto You can go into one with jump and go out of it again before its end with return (doesn't give back any result, only stops the subroutine) Handled just like normal code - Global scope like goto So I wanted to know: Is the idea above good? What are the (dis)advantages? Would there be a better combination of function and goto or even a completely new idea?

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• Aaron Hillegass Chapter 18 Challenge Question

  - by jasonbogd

  I am working through Aaron Hillegass' Cocoa Programming for Mac OS X and am doing the challenge for Chapter 18. Basically, the challenge is to write an app that can draw ovals using your mouse, and then additionally, add saving/loading and undo support. I'm trying to think of a good class design for this app that follows MVC. Here's what I had in mind: Have a NSView-subclass that represents an oval (say JBOval) that I can use to easily draw an oval. Have a main view (JBDrawingView) that holds JBOvals and draws them. The thing is that I wasn't sure how to add archiving. Should I archive each JBOval? I think this would work, but archiving an NSView doesn't seem very efficient. Any ideas on a better class design? Thanks.

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• Resizing screenshots/screen captures for inclusion in Beamer

  - by Stephen

  Sorry, this may or may not be a programming question directly, but I am trying to resize screenshots with Imagemagick and Gimp to include in a Beamer presentation, but it comes out even blurrier than the resizing done by LaTeX. For instance, in Beamer I might have a command to rescale the image \includegraphics[width=.5\textwidth]{fig.png}. Using something like \begin{frame} \message{width = \the\textwidth} \message{height = \the\textheight} \end{frame} I have gotten the \textwidth and \textheight parameters in points (345.69548, 261.92444). So I have a script (in Python) that sends a system call to Imagemagick: 'convert %s -resize %.6f@ resized_%s' % (f,a,f) where a is calculated as \textwidth*\textheight*0.5**2. When I then go back into my Beamer presentation and include the resized figure, \includegraphics{resized_fig.png}, the size looks approximately correct but it's super-blurry. I also tried resizing in Gimp (using the GUI) but no luck either... help? Thanks...

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• iPhone Foundation - performance implications of mutable and xxxWithCapacity:0

  - by Adam Eberbach

  All of the collection classes have two versions - mutable and immutable, such as NSArray and NSMutableArray. Is the distinction merely to promote careful programming by providing a const collection or is there some performance hit when using a mutable object as opposed to immutable? Similarly each of the collection classes has a method xxxxWithCapacity, like [NSMutableArray arrayWithCapacity:0]. I often use zero as the argument because it seems a better choice than guessing wrongly how many objects might be added. Is there some performance advantage to creating a collection with capacity for enough objects in advance? If not why isn't the function something like + (id)emptyArray?

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