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  • How does a custom accessor method implementation in Core Data look like?

    - by dontWatchMyProfile
    The documentation is pretty confusing on this one: The implementation of accessor methods you write for subclasses of NSManagedObject is typically different from those you write for other classes. If you do not provide custom instance variables, you retrieve property values from and save values into the internal store using primitive accessor methods. You must ensure that you invoke the relevant access and change notification methods (willAccessValueForKey:, didAccessValueForKey:, willChangeValueForKey:, didChangeValueForKey:, willChangeValueForKey:withSetMutation:usingObjects:, and didChangeValueForKey:withSetMutation:usingObjects:). NSManagedObject disables automatic key-value observing (KVO, see Key-Value Observing Programming Guide) change notifications, and the primitive accessor methods do not invoke the access and change notification methods. In accessor methods for properties that are not defined in the entity model, you can either enable automatic change notifications or invoke the appropriate change notification methods. Are there any examples that show how these look like?

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  • Converting a constantly changing scalar value to a changing interval or frequency

    - by eco_bach
    Although I'm coding in Objective C, this is more of a general programming question. What is the best way to convert a constantly changing scalar value to a changing interval or frequency? Right now every time the scalar value changes I am destroying the NSInterval ie [self.myTimer invalidate]; self.myTimer = nil; and creating a new one, but this seems like a VERY expensive way to achieve my goal, since the changing scalar value in my case represents the horizontal velocity of a swipe. For a rough analogy, think of the speed of a swipe being reflected in a visual metronome, the faster you swipe, the higher(shorter interval) the frequency of the metronome.

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  • Need example of how to create/manipulate image pixel data with iPhone SDK

    - by whiskeyspider
    Looking for a simple example or link to a tutorial. Say I have a bunch of values stored in an array. I would like to create an image and update the image data from my array. Assume the array values are intensity data and will be updating a grayscale image. Assume the array values are between 0 and 255 -- or that I will convert it to that range. This is not for purposes of animation. Rather the image would be updated based on user interaction. This is something I know how to do well in Java, but am very new to iPhone programming. I've googled some information about CGImage and UIImage -- but am confused as to where to start. Any help would be appreciated.

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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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  • Java Program Design Layout Recommendations?

    - by Leebuntu
    I've learned enough to begin writing programs from scratch, but I'm running into the problem of not knowing how to design the layout and implementation of a program. To be more precise, I'm having difficulty finding a good way to come up with an action plan before I dive in to the programming part. I really want to know what classes, methods, and objects I would need beforehand instead of just adding them along the way. My intuition is leading me to using some kind of charting software that gives a hierarchal view of all the classes and methods. I've been using OmniGraffle Pro and while it does seem to work somewhat, I'm still having trouble planning out the program in its entirety. How should I approach this problem? What softwares out there are available to help with this problem? Any good reads out there on this issue? Thanks so much! Edit: Oh yeah, I'm using Eclipse and I code mainly in Java right now.

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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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  • How to integrate access control with my ORM in a .net windows form application?

    - by Ying
    I am developing a general database query tools, a .Net 3.5 Windows Form application. In order to make the presentation layer is independent of the database layer. I use an ORM framework, XPO from DevExpress. But, I have no access control function built in. I surfed Internet and I found in WCF Data Services, there is an interesting concept, Interceptor, which is following AOP(Aspect Oriented Programming). I am wondering who has such an experience to build access control in ORM. My basic requirement is : It should be a general method and controlled by users in runtime. So any hard coding is not acceptable. It could be based on attribute, database table, or even an external assembly. I am willing to buy a ready solution. According to the idea of AOP, an access control function can be integrated with existing functions easily and nearly not knowingly to the previous developer;) Any suggestions are welcome.

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  • Will PHP Die In Web Page Development World?

    - by Morgan Cheng
    I know that PHP is still the most popular web programming language in the world. This question just want to bring some of my concerns about PHP. PHP is naturally bound to C10K problem. Since PHP (generally run in Apache) cannot be event-driven or asynchronous, each HTTP request will occupy at least one thread or process. This makes it resistant to be more scalable. Currently, a lot of web sites (like Facebook) with high performance and scalability still depends on PHP in their front end servers. I suppose it is due to legacy reason. Is it possible that PHP will be replaced by language more suitable for C10K?

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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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  • 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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  • What is the best way to render sprites using OpenGL?

    - by Sam152
    I have been digging around for the past couple of days for a good way to render small sprites using OpenGL and glut. I have tried different libraries including EasyBMP and a few others but all of them seem to have some sort of problem with them that I cannot solve. I want to be able to take image data (I don't care what format it is or what I have to do to it to get it to work) and under the context of games programming use it on the screen. What is the best way to achieve this? I seem to be running around in circles.

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  • Question about when and when not to raise events (C#)

    - by NoPyGod
    I am programming an instant messaging library for MSN Messenger, and I have a simple question about raising events. When logging in, should I be raising UserAdded for each user that is synchronized (already on the contact list), or should the UserAdded event be reserved for when a new user has been added to the contact list via the AddUser method? Should I perhaps use another event, UserDownloaded for when a user is downloaded? Similarly, when I call logout, should I call UserRemoved? I hope this makes sense. Thank you

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  • iPhone interface design considerations: checkbox and drop-down menu ?

    - by Jesse Armand
    This may not be a programming question, but I don't know where to ask for this and it's still related. We all know that the checkbox and drop-down menu is a UI paradigm brought in from HTML or web interface. I'm not asking for code implementations here. A google search had produced many results. Although if anyone is willing to share that's great. So the question is: Is this a good design approach if we just want to provide a checkbox or drop-down functionality? (e.g. for quizzes, or forms)

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  • How Do I Remove The First 4 Characters From A String If It Matches A Pattern In Ruby

    - by James
    I have the following string: "h3. My Title Goes Here" I basically want to remove the first 4 characters from the string so that I just get back: "My Title Goes Here". The thing is I am iterating over an array of strings and not all have the h3. part in front so I can't just ditch the first 4 characters blindly. I have checked the docs and the closest think I could find was chomp, but that only works for the end of a string. Right now I am doing this: "h3. My Title Goes Here".reverse.chomp(" .3h").reverse This gives me my desired output, but there has to be a better way right? I mean I don't want to reverse a string twice for no reason. I am new to programming so I might have missed something obvious, but I didn't see the opposite of chomp anywhere in the docs. Is there another method that will work? Thanks!

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  • Learning about version control systems, Git, SVN

    - by anijhaw
    I am a basic SVN user now trying to learn GIT for a new position. I am trying the usual reading docs and watching videos. However after doing all that I still feel that there is a lot that I do not know. I was wondering if there is a place like project Euler for programming languages, that provides a series of exercises that you can do just to increase your confidence and test your knowledge about a version control system. Something thats generic enough and gets you up to speed with how to do basic things. This could also serve as a comparison point of sorts between multiple VCSs, that would show what things are easy in which VCS. If there is nothing I was planning to document my journey in learning GIT and the create an exercise of this sort.

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  • What Visual C++ references are worth a look for a Java programmer looking to get up to speed?

    - by Terry V.
    I have a lot of experience with Java/OO. There are tons of C++ tutorials/references out there, but I was wondering if there are a few key ones that a Java programmer might find useful when making the transition. I will be moving from server-side J2EE to Windows Visual C++ desktop programming. I have googled and found tons of resources, but am overwhelmed and don't know where to best spend my time. I have only a few days to get a good start. Is Visual Studio Express / Microsoft Visual C++ the best IDE for me to start with? Also, any words of wisdom from others who know and work with both languages?

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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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  • Is the F# language reference documentation available in an offline format (PDF, CHM)?

    - by stakx
    I've found several posts on hubFS of people asking if there is, or will be, offline documentation for F#. These posts haven't been answered. So I want to give it a shot and ask the same question here on SO. Where I've looked for offline documentation so far: The April 2010 CTP release of Visual F# (version 2.0) is available for VS 2008, but it doesn't come without an offline help. There's a question on SO about offline documentation for various programming languages, but F# isn't mentioned there at the time of this writing. There is of course Microsoft's F# language reference documentation (available on MSDN), which could be downloaded for offline browsing using e.g. wget. Question: Does anyone know whether any "official" offline documentation is on the way, anytime soon? (And related to this, albeit this probably can't be answered objectively: Would it be reasonable to expect that F# likely won't undergo ECMA or ISO standardization, ie. there likely won't be a standards document describing the language?)

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  • How created method with signature as List

    - by London
    Hi all, I'm very new to Java programming language so this is probably dumb question but I have to ask it because I can't figure it out on my own. Here is the deal. I want to create method which extracts certain object type from a list. So the method should receive List as argument, meaning list should contain either Object1 or Object2. I've tried like this : public Object1 extractObject(List<?>){ //some pseudo-code ... loop trough list and check if list item is instance of object one return that instance } The problem with declaring method with List<?> as method argument is that I receive compilation error from eclipse Syntax error on token ">", VariableDeclaratorId expected after this token. How do I set the method signature properly to accept object types either Object1 or Object2 ? Thank you

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  • File Explorer using Java - how to go about it?

    - by user299988
    Hi, I am set to create a file explorer using Java. The aim is to emulate the behavior of the default explorer as closely as possible, whatever may be the underlying OS. I have done NO GUI programming in Java. I have looked-up Swing, SWT and JFace, and I am beginning my project with this tutorial: http://www.ibm.com/developerworks/opensource/library/os-ecgui1/ I would like to know your opinions about the best approach to tackle this problem. If you could comment on complexity of coding, portability and OS-independence, and efficiency, it would be great. Is there anything else I should know? Do some other ways exist? Thanks a lot!

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  • Are QR codes guaranteed to work?

    - by Kiz
    Not sure if this will get closed as "not a real question" but I asked this on Superuser and it was closed for that very reason. We are thinking of implementing a QR code which will be sent to a number of users via an email which links through to a webpage. Now I'm aware that you can just Google 'QR codes' and there are a plethora of options that allow you to make a QR code. My question is thus; if we do go with this solution can we guarantee that it would work cross platform? I.e. on Android, iOS, Symbian etc? Once a QR code is generated will it work on ANY app on ANY platform? Thanks and apologies if this is not really a 'programming question' Thanks Kiran

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  • controlling bluetooth connection in matlab

    - by Mehreen Shahid
    we have a project in which we have to pick randomly generated numbers from a remote device, say mobile. there is a simple java application to generate numbers. next, we have to recieve those numbers in our matlab program via bluetooth connection with the device. assuming those numbers are temperature readings, we want to recieve a new number after every 10 sec and display the number on our matlab GUI program. the problem is do we implement bluetooth protocol through our programming? or use the matlab templates? because otherwise whenever we want to transfer file from a mobile to computer, we have to manually click "recieve a file" in blutooth wizard , just like we normally do to transfer a file. we want to enable the connection once, and then recieve text files after every 10 seconds to be read in our matlab program. can anyone please tell is it even possible in matlab? if yes, how do we establish such an automatic real time connection?

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  • How do i connect with dart community to suggest something

    - by Muhammad Umer
    I am new to this stackoverflow and programming. So HI!!!! What i hope to do is tell something that i think is important to Dart community. If somehow it was possible to code android and or iphone apps using dart that would be very awesome and same for Dart.... There is one path, that is making program in dart compiling it to javascript and then making app using Adobe air..... .But looks inefficient. so is there any other way which i am unaware of, via which i can build an android app at least.. using dart i know you can build an app, using javascript..and css+html...so i am looking for html+css+dart. It'd be cool if adobe air supports dart language directly.

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  • What are the Ruby Gotchas a newbie should be warned about?

    - by MiniQuark
    I have recently learned the Ruby programming language, and all in all it is a good language. But I was quite surprised to see that it was not as simple as I had expected. More precisely, the "rule of least-surprise" did not seem very respected to me (of course this is quite subjective). For example: x = true and false puts x # displays true! and the famous: puts "zero is true!" if 0 # zero is true! What are the other "Gotchas" you would warn a Ruby newbie about?

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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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