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• Comparison between pointer and integer (cocoa)

  - by Cal S

  Hi, I'm just learning cocoa (coming from C#) but I'm getting a strange error for something that seems really simple... (charsSinceLastUpdate=36) #import "CSMainController.h" @implementation CSMainController //global vars int *charsSinceLastUpdate = 0; NSString *myString = @"Hello world"; // - (void)applicationDidFinishLaunching:(NSNotification *)aNotification { ... } //other functions - (void)textDidChange:(NSNotification *)aNotification { NSLog(@"charsSinceLastUpdate=%i",charsSinceLastUpdate); if (charsSinceLastUpdate>=36) { // <- THIS line returns the error: Comparison between pointer and integer charsSinceLastUpdate=0; [statusText setStringValue:@"Will save now!"]; } else { charsSinceLastUpdate++; [statusText setStringValue:@"Not saving"]; } } //my functions - (void)showNetworkErrorAlert:(BOOL)showContinueWithoutSavingOption { ... } // @end Any help would be appreciated, thanks!

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• Element point map for html5 canvas element, need algorithm

  - by Artiom Chilaru

  I'm currently working on a pure html 5 canvas implementation of the "flying tag cloud sphere", which many of you have undoubtedly seen as a flash object in some pages. The tags are drawn fine, and the performance is satisfactory, but there's one thing in the canvas element that's kind of breaking this idea: you can't identify the objects that you've drawn on a canvas, as it's just a simple flat "image".. What I have to do in this case is catch the click event, and try to "guess" which element was clicked. So I have to have some kind of matrix, which stores a link to a tag object for each pixel on the canvas, AND I have to update this matrix on every redraw. Now this sounds incredibly inefficient, and before I even start trying to implement this, I want to ask the community - is there some "well known" algorithm that would help me in this case? Or maybe I'm just missing something, and the answer is right behind the corner? :)

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• Which data structure for List of objects + datagrid wiev

  - by Martin

  Hi, I have to develop a code which will store a list of objects, as example below 101, value 11, value 12, value 13 ...etc 102, value 21, value 22, value 23 ...etc 103, value 31, value 32, value 33 ...etc 104, value 41, value 42, value 43 ...etc Now, the difficulty is, that first column is an identifier, and whole table should always be sorted by it. Easy access to each element is required. Additionally, list should be easily updated, and extended by adding element at the end as well as in front and still keep being sorted by first column. Finally, I would like to be able to display values of the above in datagridview. What is most important is a performance of the implementation, as rows will be updated many times per second, and datagridview should be able to display all changes immediately. I was thinking about creating class for the values, and then a Dictionary but encountered a problem with displaying values in gridview. What would be the most optimal way of implementing the code? Thanks in advance Martin

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• What's the correct way to stop a background process on Mac OS X?

  - by mcsheffrey

  I have an application with 2 components: a desktop application that users interact with, and a background process that can be enabled from the desktop application. Once the background process is enabled, it will run as a user launch agent independently of the desktop app. However, what I'm wondering is what to do when the user disables the background process. At this point I want to stop the background process but I'm not sure what the best approach is. The 3 options that I see are: Use the 'kill' command. Direct, but not reliable and just seems somewhat "wrong". Use an NSMachPort to send an exit request from the desktop app to the background process. This is the best approach I've thought of but I've run into an implementation problem (I'll be posting this in a separate query) and I'd like to be sure that the approach is right before going much further. Something else??? Thank you in advance for any help/insight that you can offer.

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• 2d parabolic projectile

  - by ndg

  I'm looking to create a basic Javascript implementation of a projectile that follows a parabolic arc (or something close to one) to arrive at a specific point. I'm not particularly well versed when it comes to complex mathematics and have spent days reading material on the problem. Unfortunately, seeing mathematical solutions is fairly useless to me. I'm ideally looking for pseudo code (or even existing example code) to try to get my head around it. Everything I find seems to only offer partial solutions to the problem. In practical terms, I'm looking to simulate the flight of an arrow from one location (the location of the bow) to another. It strikes me there are two distinct problems here: determining the position of interception between the projectile and a (moving) target, and then calculating the trajectory of the projectile. Any help would be greatly appreciated.

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• How to handle failure to release a resource which is contained in a smart pointer?

  - by cj

  How should an error during resource deallocation be handled, when the object representing the resource is contained in a shared pointer? Smart pointers are a useful tool to manage resources safely. Examples of such resources are memory, disk files, database connections, or network connections. // open a connection to the local HTTP port boost::shared_ptr<Socket> socket = Socket::connect("localhost:80"); In a typical scenario, the class encapsulating the resource should be noncopyable and polymorphic. A good way to support this is to provide a factory method returning a shared pointer, and declare all constructors non-public. The shared pointers can now be copied from and assigned to freely. The object is automatically destroyed when no reference to it remains, and the destructor then releases the resource. /** A TCP/IP connection. */ class Socket { public: static boost::shared_ptr<Socket> connect(const std::string& address); virtual ~Socket(); protected: Socket(const std::string& address); private: // not implemented Socket(const Socket&); Socket& operator=(const Socket&); }; But there is a problem with this approach. The destructor must not throw, so a failure to release the resource will remain undetected. A common way out of this problem is to add a public method to release the resource. class Socket { public: virtual void close(); // may throw // ... }; Unfortunately, this approach introduces another problem: Our objects may now contain resources which have already been released. This complicates the implementation of the resource class. Even worse, it makes it possible for clients of the class to use it incorrectly. The following example may seem far-fetched, but it is a common pitfall in multi-threaded code. socket->close(); // ... size_t nread = socket->read(&buffer[0], buffer.size()); // wrong use! Either we ensure that the resource is not released before the object is destroyed, thereby losing any way to deal with a failed resource deallocation. Or we provide a way to release the resource explicitly during the object's lifetime, thereby making it possible to use the resource class incorrectly. There is a way out of this dilemma. But the solution involves using a modified shared pointer class. These modifications are likely to be controversial. Typical shared pointer implementations, such as boost::shared_ptr, require that no exception be thrown when their object's destructor is called. Generally, no destructor should ever throw, so this is a reasonable requirement. These implementations also allow a custom deleter function to be specified, which is called in lieu of the destructor when no reference to the object remains. The no-throw requirement is extended to this custom deleter function. The rationale for this requirement is clear: The shared pointer's destructor must not throw. If the deleter function does not throw, nor will the shared pointer's destructor. However, the same holds for other member functions of the shared pointer which lead to resource deallocation, e.g. reset(): If resource deallocation fails, no exception can be thrown. The solution proposed here is to allow custom deleter functions to throw. This means that the modified shared pointer's destructor must catch exceptions thrown by the deleter function. On the other hand, member functions other than the destructor, e.g. reset(), shall not catch exceptions of the deleter function (and their implementation becomes somewhat more complicated). Here is the original example, using a throwing deleter function: /** A TCP/IP connection. */ class Socket { public: static SharedPtr<Socket> connect(const std::string& address); protected: Socket(const std::string& address); virtual Socket() { } private: struct Deleter; // not implemented Socket(const Socket&); Socket& operator=(const Socket&); }; struct Socket::Deleter { void operator()(Socket* socket) { // Close the connection. If an error occurs, delete the socket // and throw an exception. delete socket; } }; SharedPtr<Socket> Socket::connect(const std::string& address) { return SharedPtr<Socket>(new Socket(address), Deleter()); } We can now use reset() to free the resource explicitly. If there is still a reference to the resource in another thread or another part of the program, calling reset() will only decrement the reference count. If this is the last reference to the resource, the resource is released. If resource deallocation fails, an exception is thrown. SharedPtr<Socket> socket = Socket::connect("localhost:80"); // ... socket.reset();

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• C++ Beginner - Best way to read 3 consecutive values from the command line?

  - by Francisco P.

  Hello everyone, I am writing a text-based Scrabble implementation for a college project. The specification states that the user's position input must be read from single line, like this: Coordinates of the word's first letter and orientation (<A – P> <1 – 15> <H ou V>): G 5 H G 5 H is the user's input for that particular example. The order, as shown, must be char int char. What is the best way to read the user's input? cin >> row >> column >> orientation will cause crashes if the user screws up. A getline and a subsequent string parser are a valid solution, but represent a bit of work. Is there another, better, way to do this, that I am missing? Thanks for your time!

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• Controlling LaTeX column flow

  - by hdhermans

  What I'm trying to do: I have a page that consists of pairs of two sentences each. The pairs are separated by a whole line break. My problem is that when I have an odd number of pairs, the second sentence will automatically be placed on the next column. How can I use LaTeX to make block structures that multicol does not ignore, to keep the two sentences together? If there's better code to solve this problem, or a better column implementation (though I don't believe I can use \twocolumn in the document declaration), please post it. My current code: \documentclass{article} \usepackage{fullpage} \usepackage{multicol} \setlength{\parindent}{0pt} \setlength{\parskip}{\baselineskip} \newcommand{\pair}[2]{ \emph{#1}\\* #2 } \begin{document} \begin{multicols}{2} \pair{Sentence 1.}{Sentence 2.} \pair{Sentence 2 (pair 2).}{Sentence 2 (pair 2).} \pair{The last pair, first sentence.}{Last sentence.} \end{multicols} \end{document} This generates: http://img541.imageshack.us/img541/3444/columns.png . The second pair is what I am trying to avoid.

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• Implementing DRY Forms

  - by virtualeyes

  Getting into Play 2.0, overall, blown away, great stuff. Anyway, wondering how one can achieve DRY forms in Play? If you look at the create & edit examples in the Computer Database Sample, you'll see that the form elements are repeated. With just 4 fields (in the sample form), no big deal, but when you're dealing with large, complex forms and/or handling many CRUD models, the duplication becomes a bigger maintenance issue. On the binding end ( form.bindFromRequest and form.fill(Foo) ), the implementation is so elegant for create/edit operations; is there a corresponding solution in the template layer?

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• Webservice and ORM Framework?

  - by Sebastian

  Does anybody know a good web framework that includes an ORM mapper and allows straight forward implementation of web services? I'm looking for a framework written in PHP or C++. I'm looking for the following features (not all of them required, some will do nicely) data definition in one place used by database and web service WSDL generation XML output/JSON output boilerplate code generation So what I would like is a framework that let's me specify the objects, the web service functions on those objects and then generate everything that is required leaving me to fill the business logic (connecting the database to the web service). Anything like that out there? Background information for why I need this: I'm looking into creating a web project: the client is a rich web application that fetches all its data using AJAX. It will be completely custom made using only a low level javascript library. The server back end is supposed to serve static content and javascript (basically the rich web application) and to provide a RESTful web service API (which I would like to implement using aforementioned framework).

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• How to implement file transfer with Java sockets?

  - by ZeKoU

  Hello, I am working on a chat implementation with Java sockets. I have focused on few functionalities, like authentication, one person chat and a group chat. I was thinking about adding file transfer functionality, and I wonder what's the good practice about this. Should I have separate socket on the server with different port listening just for file transfers? Right now input and output streams that I get from server socket are binded to Scanner and PrintWriter objects respectively, so I find it hard to use that for file transfer. Any patterns you guys could recommend or give me good recommendations are very appreciated. Thanks, ZeKoU

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• RSA implementations for Java, alternative to BC

  - by Tom Brito

  The RSA implementation that ships with Bouncy Castle only allows the encrypting of a single block of data. The RSA algorithm is not suited to streaming data and should not be used that way. In a situation like this you should encrypt the data using a randomly generated key and a symmetric cipher, after that you should encrypt the randomly generated key using RSA, and then send the encrypted data and the encrypted random key to the other end where they can reverse the process (ie. decrypt the random key using their RSA private key and then decrypt the data). I can't use the workarond of using symmetric key. So, are there other implementations of RSA than Bouncy Castle?

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• How to increment a value using a C-Preprocessor in Objective-C?

  - by mystify

  Example: I try to do this: static NSInteger stepNum = 1; #define METHODNAME(i) -(void)step##i #define STEP METHODNAME(stepNum++) @implementation Test STEP { // do stuff... [self nextFrame:@selector(step2) afterDelay:1]; } STEP { // do stuff... [self nextFrame:@selector(step3) afterDelay:1]; } STEP { // do stuff... [self nextFrame:@selector(step4) afterDelay:1]; } // ... When building, Xcode complains that it can't increment stepNum. This seems logical to me, because at this time the code is not "alive" and this pre-processing substitution stuff happens before actually compiling the source code. Is there another way I could have an variable be incremented on every usage of STEP macro, the easy way?

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• Standard Workflow when working with JPA

  - by jschoen

  I am currently trying to wrap my head around working with JPA. I can't help but feel like I am missing something or doing it the wrong way. It just seems forced so far. What I think I know so far is that their are couple of ways to work with JPA and tools to support this. You can do everything in Java using annotations, and let JPA (whatever implementation you decide to use) create your schema and update it when changes are made. You can use a tool to reverse engineer you database and generate the entity classes for you. When the schema is updated you have to regenerate these classes, or manually update them. There seems to be drawbacks to both, and benefits to both (as with all things). My question is in an ideal situation what is the standard workflow with JPA? Most schemas will require updates during the maintenance phase and especially during the development phase, so how is this handled?

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• Fast parsing of PHP in C#

  - by Jessica Shea

  Hello there, I've got a requirement for parsing PHP files in C#. We essentially require some of the devs in another country to upload PHP files and once uploaded we need to check the php files and get a list of all the methods and classes/functions etc. I thought of using a regex but I can't workout if a function belongs to a class etc, so I was wondering if theres already something 'out there' that will parse out PHP files and spit out its functions (I'm trying to avoid writing a full blow AST implementation). Does anyone have any idea? I looked at Coco/R but I couldn't find a PHP grammar file. I'm using .NET 2.0 and C#.

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• Delphi 2010 " is" statement behaves differently than Delphi 7's?!

  - by Tom1952

  Why does the code below return TRUE in Delphi 7 and FALSE in Delphi 2010? TBitBtn is a descendant of TButton. type TForm1 = class(TForm) Button1: TButton; BitBtn1: TBitBtn; procedure Button1Click(Sender: TObject); private public end; var Form1: TForm1; implementation {$R *.dfm} procedure TestControl( aControl: TControl); begin if (aControl is TButton) then showmessage('TRUE') else showmessage('FALSE'); end; procedure TForm1.Button1Click(Sender: TObject); begin TestControl(BitBtn1); end;

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• PHP Doxygen Collaboration Diagrams

  - by Shabbyrobe

  I've started playing around with doxygen to generate documentation from my PHP code. I notice there are two diagrams in the generated output - inheritance and collaboration. I know about the inheritance one, but the collaboration one has piqued my interest since reading the manual: If the COLLABORATION_GRAPH and HAVE_DOT tags are set to YES then doxygen will generate a graph for each documented class showing the direct and indirect implementation dependencies (inheritance, containment, and class references variables) of the class with other documented classes. The impression I get from that description is that composition relationships should be represented by the collaboration diagram as well, but it always seems to just be identical to the inheritance one. Is there something I can do to hint to Doxygen the things I would like to appear in this diagram? Does it just not work with PHP?

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• Receiving a File via RFCOMM on Android

  - by poeschlorn

  Hey guys, does someone know how to receive a file on android via RFCOMM? I'm a newby to bluetooth issues, so please have patience with me. I'm looking for an approach to receive data via RFCOMM as a stream and store it somewhere on my phone. Saving data is not the problem, it works quite fine. The main issue is the implementation of the connection and the reliable retrieval of the data... This whole procedure should be implemented as an android service (so that no activity has to be launched while receiving data). What would you suggest: Local or remote service? greetz, poeschlorn

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• Using Linq to select a range of members in a list

  - by clintp

  Given a list of elements like so: int[] ia = new int[] { -4, 10, 11, 12, 13, -1, 9, 8, 7, 6, 5, 4, -2, 6, 15, 32, -5, 6, 19, 22 }; Is there an easy way in Linq to do something along the lines of "Select the elements from the -1 up to the next negative number (or the list exhausts)"? A successful result for -1 would be (-1, 9, 8, 7, 6, 5, 4). Using -2 would give the result (-2, 6, 15, 32). Not a homework problem. I'm just looking at an implementation using a bool, a for loop, and an if wondering if there's a cleaner way to do it.

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• What's the standard behaviour for an out parameter when a TryXxxx method returns false?

  - by Matt Lacey

  Assuming a method with the following signature bool TryXxxx(object something, out int toReturn) What is it acceptable for toReturn to be if TryXxxx returns false? In that it's infered that toReturn should never be used if TryXxxx fails does it matter? If toReturn was a nulable type, then it would make sense to return null. But int isn't nullable and I don't want to have to force it to be. If toReturn is always a certain value if TryXxxx fails we risk having the position where 2 values could be considered to indicate the same thing. I can see this leading to potential possible confusion if the 'default' value was returned as a valid response (when TryXxxx returns true). From an implementation point if view it looks like having toReturn be a[ny] value is easiest, but is there anything more important to consider?

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• Is it possible to use AutoMapper to wrap methods?

  - by Woj

  I have two classes: public class TestClass1 { public int TestInt { get; set; } public void TestMethod() { // Do something } } public class TestClass2 { public int TestInt { get; set; } public void TestMethod() { // Do something } } I want to create interface that I can use for both classes. The easiest solution is to implement the interface on TestClass1 and TestClass2 but I don;t have access to the implementation of these classes (external dll). I was wondering if I can create new interface and use AutoMapper to map TestClass1 and TestClass2 to ITestInterface: public interface ITestInterface { int TestInt { get; set; } void TestMethod(); }

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• Hiding an internal interface in a "friend" assembly

  - by dmo

  I have two assemblies: A and B. A has InternalsVisibleTo set for B. I would like to make calls from A to get information that can only be known by a type defined in B in a way that keeps things internal. I can do this using an internal interface defined in A and implemented explicitly in B. Assembly A internal interface IHasData { Data GetData(); } class ClassA { DoSomething(IHasData); } Assembly B public abstract class ClassB : IHasData { Data IHasData.GetData() { /** do something internal **/ } } The trouble comes when someone references assembly B and derives from ClassB - they get the error: "The type 'AssemblyA.IHasData' is defined in an assembly that is not referenced" even though that type should be invisible to them. If I look at the public type definition I see what I expect - ClassB with no interfaces implemented. Why do I get this error? All of the implementation is in assembly B. I could use IHasData internally in ClassB and that wouldn't require assembly A to be referenced. Can someone help me understand what is going on?

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• fluent nhibernate not caching queries in asp.net mvc

  - by AWC

  I'm using a fluent nhibernate with asp.net mvc and I not seeing anything been cached when making queries against the database. I'm not currently using an L2 cache implementation. Should I see queries being cached without configuring an out of process L2 cache? Mapping are like this: Table("ApplicationCategories"); Not.LazyLoad(); Cache.ReadWrite().IncludeAll(); Id(x => x.Id); Map(x => x.Name).Not.Nullable(); Map(x => x.Description).Nullable(); Example Criteria: return session .CreateCriteria<ApplicationCategory>() .Add(Restrictions.Eq("Name", _name)) .SetCacheable(true); Everytime I make a request for an application cateogry by name it is hitting the database is this expected behaviour?

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• xcode - warning there's no getter/setter for property not even mentioned in the code!!

  - by alexeyndru

  I got the warning : property 'textField' requires method '-textField' to be defined - use @synthesize, @dynamic or provide a method implementation. Now, there is no such property defined in my project! More bizarre, if I just click save in Interface builder and build again, the build is successful - though, right on the line with '@end' the warning appears. Also weird: if I begin to write some code ..and then delete it just the way it was before writing it (maybe not code..anything) and then build&go the warning with the textField appears again. Could be a bug of sdk? What could be happening?

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• Caching the response of an ASP.NET HTTP Handler server and client side

  - by Bert Vandamme

  Is it possible to cache the response of a http handler on the server and on the client? This doesn't seem to be doing the trick: _context.Response.Cache.SetCacheability(HttpCacheability.Public); _context.Response.Cache.SetExpires(DateTime.Now.AddDays(7)); The _context is the HTTPContext passed as an argument to the ProcessRequest method on the IHttpHandler implementation. Any ideas? Update: The client does cache images that are loaded through the httphandler, but if another client does the same call, the server hasn't got it cached. So for each client that asks for the image, the server goes to the database (and filestream). If we use a aspx page instead of a httphandler together with a caching profile, then the images are cached both on the client and the server.

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