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• Locking a file to verify a single execution of a service. How reliable?

  - by Camilo Díaz

  Hello, I am deploying a little service to an UNIX(AIX) system. I want to check if there is no active instance of that service running when starting it. How reliable is to implement that check like this? Try to acquire a lock on a file (w/ FileChannel) If succeeds, keep lock and continue execution If fails, exit and refuse to run the main body I am aware of software like the Tanuki wrapper, however, I'm longing for a simpler(maybe not portable) solution. Regarding PIDFILE(s): I want to avoid using them if possible, as I don't have administrative rights on the machine, neither knowledge in AIX's shell programming.

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• whats faster, more efficient, loading a js file with arrays or populating arrays from tables

  - by Leigh

  I am rebuilding an ecom site where the product data is stored in a multidimensional JS array that gets loaded on page load. This data is constantly being accessed with JS due to the nature of the site, to update prices based on user selections. There are many options that affect final price. From a programming standpoint, a DB table is much easier to maintain and update than are JS arrays, and since I am porting the site over to PHP and MYSQL, I have been considering moving these arrays into tables. So, would it be better to populate an array from the DB on load so that the pricing data is always available to the JS, or stay with hard coded JS files? I considered getting data via ajax as needed, but since this site has to constantly update pricing with user interaction, I have pretty much ruled that out. How would you handle it?

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• Easiest, free way to start with Flex?

  - by Jon

  I'm interested in getting started with Flex, as I've wanted to work with flash for quite awhile but have never liked the designer-oriented way of programming. I've heard flex can be used for free, and is programmer friendly, but I'm having some issues... I can't find any good sites with flex resources. I'm used to PHP, so maybe I'm spoiled with a full manual, comments and tutorials, but I can't even find a decent tutorial site. So, what are some good flex starts to get started, and what's a good, free IDE to program with?

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• Licensing Android Apache Commons Math

  - by stefple

  I am about to release my first commercial software ever. I didnt study something related to programming so i am facing a problem here, which is licensing. I am not native english speaking, so i have a little bit of a problem when i read the Apache Commons License. In my software i use the Apache Commons Math library. If i understand their FAQ i just may distribute my software if i add this (the text will come up at my "info" screen inside the app): [...] \nCopyright 2012 xxxstefplexxxx \n\n This software uses Apache Commons Math Library \nThe license can be found here: \nhttp://www.apache.org/licenses/LICENSE-2.0 \n

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• resetting the image in an NSView

  - by Josan

  I think this is a very simple question, but I’m new to programming so I may be going about it in a wrong-headed way. I have a basic understanding of Objective-C writing terminal applications and am teaching myself how to use the Cocoa GUI. I understand how to use IBOutlet and IBAction to connect a simple button to a method that will repeatedly send random numbers to a textfield . I understand how to add a NSView file, connect it to a custom view in interface builder and draw a path through random points in the view when the application launches. (I’ve been putting this code inside the - (void)drawRect:(NSRect)dirtyRect method that is declared when the file is created). What I can’t seem to figure out is how to connect a button to an action that will then ‘refresh’ the view – in this case repopulate it with another set of random points connected with a path. Looking at the documentation, I think I should somehow be using – (void) setNeedsDisplay(BOOL)flag but nothing I have tried so far had worked. Please tell me, what am I missing here?

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• Favicon to PNG in PHP

  - by sailtheworld

  I need a PHP script to convert favicons to PNGs while keeping their original dimensions. I know Google has it's secret icon converter - http://www.google.com/s2/favicons?domain=http://facebook.com/ but this converts favicons to 16x16 even if they they were originally larger. So basically I need this, minus the shrinking effect. I've also seen this - http://www.controlstyle.com/articles/programming/text/php-favicon/ but I couldn't get it to work after hours of messing around with it. Basically I am trying to automatically grab the icon for a link that will be as large as possible - automatically 48x48 png based on a URL would be the perfect scenario, but I don't know of any humanly possible way to do this given that no websites happen to keep a 48x48 icon in a publicly accessible spot. Does anybody know of a script/service or have a suggestion? Thanks!

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• Succinct code over verbose?

  - by WeNeedAnswers

  With C# becoming more and more declarative and becoming the new Swiss army knife of Programming. Is it better to be succinct thus reducing the actual code base, or long winded but verbose. Is there a performance issue with succinct or does being succinct improve performance because your putting more of your code in the hands of the compiler. (LINQ being an example when used correctly). I know that verbosity should override succinct where code would become less readable, but is this a good idea when your style could affect the performance.

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• Learning Python coming from PHP

  - by Coronatus

  Community wiki so don't vote to close, kthxbai. My dynamic language experience is solely PHP. I want to learn Python now to broaden my career opportunities and just because I like programming. :) When learning Java, I used a site (lost the URL/real name now), something like "Java for PHP developers" that had all on one side of the page the PHP code, and on the other side the Java code to do the same thing. Is there a website like that for Python? Any other recommendations/advice? Thanks Edit: I have no votes left today, but I'll up-vote good answers tomorrow :)

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• [SCORM 2004] the cmi.total_time parameter does not return anything.

  - by Nephila

  I am programming a SCORM 2004 product. I can update the session_time, it works. I can set the status (passed, failed, etc...) I also can get the cmi.location time. No problems! But I don't succeed atingt get the total time (cmi.total_time). I have tested on 2 LMS: On Ganesha the API.GetValue('cmi.total_time') is an empty string. On Moodle the API.GetValue('cmi.total_time') is just a "P". I do have the correct logs with correct session times. EDIT. I also try on cloud.scorm.com and cmi.total_time returns each time PT0H0M0S.

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• Aquamacs and IDLWAVE

  - by nicolavianello

  I've just installed the new Aquamacs 2.0 in my Mac Os X 10.6.3 and I'm an happy user of IDLWAVE on Aquamacs for programming in IDL. Unfortunately I run into a problem which I can't understand. I used in my configuration file to put the following (setq idlwave-surround-by-blank t) for the beautiful space around operator. This used to work till Aquamacs 2.0 preview b3 (third beta release) from that on, it stops to work and every time I type an operator (the same for '=' '<' '' etc) I got the following message Debugger entered--Lisp error: (void-variable idlwave-expand-equal) (lambda nil (interactive) (self-insert-command 1) idlwave-expand- equal -1 -1)() call-interactively((lambda nil (interactive) (self-insert-command 1) idlwave-expand-equal -1 -1) nil nil) Any help is welcommed

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• Why "do...while" does not exist in F#

  - by Kev

  I cannot find "do...while..." I have to code like this: let bubbleSort a= let n = Array.length a let mutable swapped = true let mutable i = 0 while swapped do swapped <- false for j = 0 to n-i-2 do if a.[j] > a.[j+1] then let t = a.[j] a.[j] <- a.[j+1] a.[j+1] <- t swapped <- true i <- i+1 The code is bad without "do...while". Sadly, "break/continue" are also not available. Is F# not suitable for non-functional-programming?

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• F# books question

  - by Michiel Borkent

  I am now reading Foundations of F# by Robert Pickering and parallelly the book in progress 'Real World Functional Programming' by Tomas Petricek. My question is, what is the added value I would get from buying and reading the following books: 1) Expert F# by Don Syme and others 2) F# for Scientists by John Harrop Are those books still up to date with the current CTP version. What are things to keep notice of with respect to the recent changes in the language? Will there be reprinted updated versions? Also I want to learn more about datamining techniques with F# as a tool for this. What are good books to read next on this topic?

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• Apache redirect multiple domain names from https

  - by Cyril N.

  My server distribute two main websites, says : www.google.com & www.facebook.com (yeah I know :p) I want them to be distributed via https. Using Apache, I defined a vhost file in sites-available/enabled containing this : <VirtualHost *:80> ServerName google.com Redirect / https://www.google.com/ </VirtualHost> <VirtualHost *:80> ServerName facebook.com Redirect / https://www.facebook.com/ </VirtualHost> <VirtualHost *:80> DocumentRoot /srv/www/google/www/ ServerName www.google.com ServerAlias www.facebook.com <Directory ... /> # Google & Facebook points to the same directory (crazy right ?) # Next of the config </VirtualHost> <VirtualHost *:443> SSLEngine On SSLCertificateFile /path/to/google.crt SSLCertificateKeyFile /path/to/google.key DocumentRoot "/srv/www/google/www/" ServerName www.google.com <Directory .../> # Next of the config </VirtualHost> <VirtualHost *:443> SSLEngine On SSLCertificateFile /path/to/facebook.crt SSLCertificateKeyFile /path/to/facebook.key DocumentRoot "/srv/www/google/www/" ServerName www.facebook.com <Directory .../> # Next of the config </VirtualHost> If I access to https://www.google.com, the httpS works correctly If I access to https://www.facebook.com, the httpS works correctly. If I access to http://www.google.com, the http works correctly # Without https ! If I access to http://www.facebook.com, the http works correctly # Without https ! BUT : If I access to https://facebook.com, it fails saying that the SSL connection is not what expected : Google.com instead of facebook.com Based on my configuration file, I understand why, so I tried to add : <VirtualHost *:443> SSLEngine On ServerName facebook.com Redirect / https://www.facebook.com/ </VirtualHost> But then, I can't even access facebook.com nor www.facebook.com via http/https. So my question is quite simple : how can I redirect all https access to facebook.com (and eventually all sub facebooks : facebook.fr, www.facebook.fr, etc) to www.facebook.com (redirecting to www domain) in HTTPS ? Thanks for your help ! :)

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• PHP - Frameworks, ORM, Encapsulation.

  - by Ian

  Programming languages/environments aside, are there many developers who are using a framework in PHP, ORM and still abide by encapsulation for the DAL/BLL? I'm managing a team of a few developers and am finding that most of the frameworks require me to do daily code inspection because my developers are using the built in ORM. Right now, I've been using a tool to generate the classes and CRUD myself, with an area for them to write additional queries/functions. What's been happening though, is they are creating vulnerabilities by not doing proper checks on data permission, or allowing the key fields to be manipulated in the form. Any suggestions, other than get a new team and a new language (I've seen Python/Ruby frameworks have the same issues).

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• Write a function in c that includes the following sequence of statements [Wont Compile]

  - by Cody

  There is a question in my programming languages textbook that is as follows: Write a C function that includes the following sequence of statements: x = 21; int x; x = 42; Run the program and explain the results. Rewrite the same code in C++ and Java and compare the results. I have written code, and played with it in all three languages but I can not even get it to compile. This includes declaring x above the three lines as well as in the calling function (as this question is obviously attempting to illustrate scoping issues) I'd like to explain the results and do the comparisons on my own, as it is an assignment question but I was wondering if anyone had any insight as to how to get this code to compile? Thanks

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• How can i determine the version of the Windows SDK installed on my computer?

  - by NuclearCheese781

  Hello everyone :) I've very recently decided to teach myself c++ and win32 programming after learning vb.net, and i've got a very simple question: How can I determine what version of the Windows SDK is installed on my computer? I'm asking so I can install the latest version if it isn't installed allready, before i start playing around with c++. I'm using Microsoft Visual Studio 2008 SP1 as my IDE. (I spent 10 minutes using Google to search for an answer, but I couldn't find one) If anyone could help me, it would be very much appreciated. Matt.

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• How to signal a buffer full state between posix threads

  - by mikip

  Hi I have two threads, the main thread 'A' is responsible for message handling between a number of processes. When thread A gets a buffer full message, it should inform thread B and pass a pointer to the buffer which thread B will then process. When thread B has finished it should inform thread A that it has finished. How do I go about implementing this using posix threads using C on linux. I have looked at conditional variables, is this the way to go? . I'm not experienced in multi threaded programming and would like some advice on the best avenue to take. Thanks

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• Can anyone recommend a primer to Erlang?

  - by Till

  I've recently found myself getting more and more interested in Erlang. I've purchased a book (Programming in Erlang) and started reading up on the basics. Reading books is time consuming so I am looking to shortcut this a bit and go back to the book later. What I lack is a good introductory tutorial. Kind of like, hands on, this is what you need to get started in Erlang, these are best practices, this is how you organize code and this is how you do a small project. I've googled this topic extensively and haven't had much luck. ;)

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• How Do I Add Value To All Previous Values In Array

  - by James

  Lets say I have the following array: my_array = [1, 5, 8, 11, -6] I need to iterate over this array and add the values prior to the current value together. An example will probably be easier to understand. I need to return an array that should look something like this: final_array = [1, 6, 14, 25, 19] I have tried doing something like this: my_array.collect {|value| value + previous_values } But obviously that doesn't work because I can't figure out how to get the previous values in the array. I am a programming noob so this might be easier than I am making it. I am pretty sure I need to use either collect or inject, but I can't seem to figure out how to do this. Any help would be appreciated.

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• iPhone write to file (alternative directory)

  - by strider2k

  New to iPhone 3.2, Apple introduced File-Sharing support. Details can be found at https://developer.apple.com/iphone/library/releasenotes/General/WhatsNewIniPhoneOS/Articles/iPhoneOS3_2.html#//apple_ref/doc/uid/TP40009337-SW1 . Now, most examples floating around in the web demonstrates writing to the documents directory. What if I want to write files from my app but I don't want the user to be able to see it via iTunes? I'm looking at the Files and Networking section of the iPhone OS Programming Guide and I'm unsure what would be a good alternative to the documents directory for writing files to hide from the user and not be rejected by Apple's review team.

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• Repeating a List in Scala

  - by Ralph

  I am a Scala noob. I have decided to write a spider solitaire solver as a first exercise to learn the language and functional programming in general. I would like to generate a randomly shuffled deck of cards containing 1, 2, or 4 suits. Here is what I came up with: val numberOfSuits = 1 (List["clubs", "diamonds", "hearts", "spades"].take(numberOfSuits) * 4).take(4) which should return List["clubs", "clubs", "clubs", "clubs"] List["clubs", "diamonds", "clubs", "diamonds"] List["clubs", "diamonds", "hearts", "spades"] depending on the value of numberOfSuits, except there is no List "multiply" operation that I can find. Did I miss it? Is there a better way to generate the complete deck before shuffling? BTW, I plan on using an Enumeration for the suits, but it was easier to type my question with strings. I will take the List generated above and using a for comprehension, iterate over the suits and a similar List of card "ranks" to generate a complete deck.

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• setNeedsDisplayInRect: paints a white rectangle only

  - by Ion Tichy

  Hi, I'm still a little fresh to CoreGraphics programming, so please bear with me. I'm trying to write an application, which allows the user to rub stuff off an image with the finger. I have the basic functionality nailed down, but the result is sluggish since the screen is redrawn completely every time a touch is rendered. I did some research and found out that I can refresh only a portion of the screen using UIView's setNeedsDisplayInRect: method. This does call drawRect: as expected, however everything I draw in the drawRect: following the setNeedsDisplayInRect: is ignored. Instead, the area in the rect parameter is simply filled with white. No matter what I draw inside, all I end up with is a white rectangle. In essence, this is what I do: 1) when user touches screen, this touch is rendered into a mask 2) when the drawRect: is called, the image is masked with that mask There must be something simple I'm overlooking, surely?

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• Is there a name for the technique of using base-2 numbers to encode a list of unique options?

  - by Lunatik

  Apologies for the rather vague nature of this question, I've never been taught programming and Google is rather useless to a self-help guy like me in this case as the key words are pretty ambiguous. I am writing a couple of functions that encode and decode a list of options into a Long so they can easily be passed around the application, you know this kind of thing: 1 - Apple 2 - Orange 4 - Banana 8 - Plum etc. In this case the number 11 would represent Apple, Orange & Plum. I've got it working but I see this used all the time so assume there is a common name for the technique, and no doubt all sorts of best practice and clever algorithms that are at the moment just out of my reach.

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• how sort recursively by maximum fileze and counts files type?

  - by user599395

  Hello! I'm beginner in bash programming. I want to display head -n $1 results of sorting files by size in /etc/*. The problem is that at final search, I must know how many directories and files has processed. I compose following code: #!/bash/bin let countF=0; let countD=0; for file in $(du -sk /etc/* |sort +0n | head $1); do if [ -f "file" ] then echo $file; let countF=countF+1; else if [ -d "file" ] then let countD=countD+1; fi done echo $countF echo $countD I have errors at execution. How use find with du, because I must search recursively?

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• Self-Configuring Classes W/ Command Line Args: Pattern or Anti-Pattern?

  - by dsimcha

  I've got a program where a lot of classes have really complicated configuration requirements. I've adopted the pattern of decentralizing the configuration and allowing each class to take and parse the command line/configuration file arguments in its c'tor and do whatever it needs with them. (These are very coarse-grained classes that are only instantiated a few times, so there is absolutely no performance issue here.) This avoids having to do shotgun surgery to plumb new options I add through all the levels they need to be passed through. It also avoids having to specify each configuration option in multiple places (where it's parsed and where it's used). What are some advantages/disadvantages of this style of programming? It seems to reduce separation of concerns in that every class is now doing configuration stuff, and to make programs less self-documenting because what parameters a class takes becomes less explicit. OTOH, it seems to increase encapsulation in that it makes each class more self-contained because no other part of the program needs to know exactly what configuration parameters a class might need.

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