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  • Multi-reader IPC solution?

    - by gct
    I'm working on a framework in C++ (just for fun for now), that lets the user write plugins that use a standard API to stream data between each other. There's going to be three basic transport mechanisms for the data: files, sockets, and some kind of IPC piping system. The system is set up so that for the non-file transport, each stream can have multiple readers. IE once a server socket it setup, multiple computers can connect and stream the data. I'm a little stuck at the multi-reader IPC system though. All my plugins run in threads so they live in the same address space, so some kind of shared memory system would work fine, I was thinking I'd write my own circular buffer with a write pointer and read pointers chassing it around the buffer, but I have my doubts that I can achieve the same performance as something like linux pipes. I'm curious what people would suggest for a multi-reader solution to something like this? Is the overhead for pipes or domain sockets low enough that I could just open a connection to each reader and issue separate writes to each reader? This is intended to be significant volumes of data (tens of mega-samples/sec), so performance is a must.

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  • How to implement a network protocol?

    - by gotch4
    Here is a generic question. I'm not in search of the best answer, I'd just like you to express your favourite practices. I want to implement a network protocol in Java (but this is a rather general question, I faced the same issues in C++), this is not the first time, as I have done this before. But I think I am missing a good way to implement it. In fact usually it's all about exchanging text messages and some byte buffers between hosts, storing the status and wait until the next message comes. The problem is that I usually end up with a bunch of switch and more or less complex if statements that react to different statuses / messages. The whole thing usually gets complicated and hard to mantain. Not to mention that sometimes what comes out has some "blind spot", I mean statuses of the protocol that have not been covered and that behave in a unpredictable way. I tried to write down some state machine classes, that take care of checking start and end statuses for each action in more or less smart ways. This makes programming the protocol very complicated as I have to write lines and lines of code to cover every possible situation. What I'd like is something like a good pattern, or a best practice that is used in programming complex protocols, easy to mantain and to extend and very readable. What are your suggestions?

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  • Best way to implement game loop without freezing UI thread

    - by Matt H
    I'm trying to make a simple 2D game in Java. So far I have a JFrame, with a menubar, and a class which extends JPanel and overrides it's paint method. Now, I need to get a game loop going, where I will update the position of images and so on. However, I'm stuck at how best to achieve this. Should I use multi-threading, because surely, if you put an infinite loop on the main thread, the UI (and thus my menu bar) will freeze up? Here's my code so far: import java.awt.Color; import java.awt.Graphics; import javax.swing.JPanel; @SuppressWarnings("serial") public class GameCanvas extends JPanel { public void paint(Graphics g) { while (true) { g.setColor(Color.DARK_GRAY); try { Thread.sleep(100); } catch (InterruptedException e) { e.printStackTrace(); } } } } import javax.swing.JFrame; import javax.swing.JMenu; import javax.swing.JMenuBar; import javax.swing.JMenuItem; @SuppressWarnings("serial") public class Main extends JFrame { GameCanvas canvas = new GameCanvas(); final int FRAME_HEIGHT = 400; final int FRAME_WIDTH = 400; public static void main(String args[]) { new Main(); } public Main() { super("Game"); JMenuBar menuBar = new JMenuBar(); JMenu fileMenu = new JMenu("File"); JMenuItem startMenuItem = new JMenuItem("Pause"); menuBar.add(fileMenu); fileMenu.add(startMenuItem); super.add(canvas); super.setVisible(true); super.setSize(FRAME_WIDTH, FRAME_WIDTH); super.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); super.setJMenuBar(menuBar); } } Any pointers/tips? Also, where should I put my loop? In my main class, or my GameCanvas class? Any help is appreciated, thanks.

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  • How to make use of Grails Dependencies in your IDE

    - by raoulsson
    Hi All, So I finally got my dependencies working with Grails. Now, how can my IDE, eg IntelliJ or Eclipse, take advantage of it? Or do I really have to manually manage what classes my IDE knows about at "development time"? If the BuildConfig.groovy script is setup right (see here), you will be able to code away with vi or your favorite editor without any troubles, then run grails compile which will resolve and download the dependencies into the Ivy cache and off you go... If, however, you are using an IDE like Eclipse or IntelliJ, you will need the dependencies at hand while coding. Obviously - as these animals will need them for the "real time" error detection/compilation process. Now, while it is certainly possible to code with all the classes shining up in bright red all over the place that are unknown to your IDE, it is certainly not much fun... The Maven support or whatever it is officially called lives happily with the pom file, no extra "jar directory" pointers needed, at least in IntelliJ. I would like to be able to do the same with Grails dependencies. Currently I am defining them in the BuildConfig.groovy and additionally I copy/paste the current jars around on my local disk and let the IDE point to it. Not very satisfactory, as I am working in a highly volatile project module environment with respect to code change. And this situation ports me directly into "jar hell", as my "develop- and build-dependencies" easily get out of sync and I have to manage manually, that is, with my brain... And my brain should be busy with other stuff... Thanks! Raoul P.S: I'm currently using Grails 1.2M4 and IntelliJ 92.105. But feel free to add answers on future versions of Grails and different, future IDEs, as the come in...

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  • Is there a table of OpenGL extensions, versions, and hardware support somewhere?

    - by Thomas
    I'm looking for some resource that can help me decide what OpenGL version my game needs at minimum, and what features to support through extensions. Ideally, a table of the following format: 1.0 1.1 1.2 1.2.1 1.3 ... multitexture - ARB ARB core core texture_float - EXT EXT ARB ARB ... (Not sure about the values I put in, but you get the idea.) The extension specs themselves, at opengl.org, list the minimum OpenGL version they need, so that part is easy. However, many extensions have been accepted and became core standard in subsequent OpenGL versions, but it is very hard to find when that happened. The only way I could find is to compare the full OpenGL standards document for each version. On a related note, I would also very much like to know which extensions/features are supported by which hardware, to help me decide what features I can safely use in my game, and which ones I need to make optional. For example, a big honkin' table like this: MAX_TEXTURE_IMAGE_UNITS MAX_VERTEX_TEXTURE_IMAGE_UNITS ... GeForce 6xxx 8 4 GeForce 7xxx 16 8 ATi x300 8 4 ... (Again, I'm making the values up.) The table could list hardware limitations from glGet but also support for particular extensions, and limitations of such extension support (e.g. what floating-point texture formats are supported in hardware). Any pointers to these or similar resources would be hugely appreciated!

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  • JavaScript window object element properties

    - by Timothy
    A coworker showed me the following code and asked me why it worked. <span id="myspan">Do you like my hat?</span> <script type="text/javascript"> var spanElement = document.getElementById("myspan"); alert("Here I am! " + spanElement.innerHTML + "\n" + myspan.innerHTML); </script> I explained that a property is attached to the window object with the name of the element's id when the browser parses the document which then contains a reference to the appropriate dom node. It's sort of as if window.myspan = document.getElementById("myspan") is called behind the scenes as the page is being rendered. The ensuing discussion we had raised a few of questions: The window object and most of the DOM are not part of the official JavaScript/ECMA standards, but is the above behavior documented in any other official literature, perhaps browser-related? The above works in a browser (at least the main contenders) because there is a window object, but fails in something like rhino. Is writing code that relys on this considered bad practice because it makes too many assumptions about the execution environment? Are there any browsers in which the above would fail, or is this considered standard behavior across the board? Does anyone here know the answers to those questions and would be willing to enlighten me? I tried a quick internet search, but I admit I'm not sure how to even properly phrase the query. Pointers to references and documentation are welcome.

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  • Coordinating typedefs and structs in std::multiset (C++)

    - by Sarah
    I'm not a professional programmer, so please don't hesitate to state the obvious. My goal is to use a std::multiset container (typedef EventMultiSet) called currentEvents to organize a list of structs, of type Event, and to have members of class Host occasionally add new Event structs to currentEvents. The structs are supposed to be sorted by one of their members, time. I am not sure how much of what I am trying to do is legal; the g++ compiler reports (in "Host.h") "error: 'EventMultiSet' has not been declared." Here's what I'm doing: // Event.h struct Event { public: bool operator < ( const Event & rhs ) const { return ( time < rhs.time ); } double time; int eventID; int hostID; }; // Host.h ... void calcLifeHist( double, EventMultiSet * ); // produces compiler error ... void addEvent( double, int, int, EventMultiSet * ); // produces compiler error // Host.cpp #include "Event.h" ... // main.cpp #include "Event.h" ... typedef std::multiset< Event, std::less< Event > > EventMultiSet; EventMultiSet currentEvents; EventMultiSet * cePtr = &currentEvents; ... Major questions Where should I include the EventMultiSet typedef? Are my EventMultiSet pointers obviously problematic? Is the compare function within my Event struct (in theory) okay? Thank you very much in advance.

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  • Can I architect a web app so it can be deployed to either the cloud or a dedicated server / VPS ? Ho

    - by CAD bloke
    Is there are an architecture versatile enough that it may be deployed to either a cloud server or to a dedicated (or VPS) server with minimal change? Obviously there would be config changes but I'd rather leave the rest of the app consistent, keeping one maintainable codebase. The app would be ASP.NET &/or ASP.MVC. My dev environment is VS 2010. The cloud may, or may not be, Azure. Dedicated or VPS would be Win Server 2008. Probably. It is not a public-facing web site. The web app I have in mind would be a separate deployment for each client. Some clients would be small-scale, some will prefer the app to run on a local intranet rather than on the web. Other clients may prefer the cloud approach for a black-box solution. The app may run for a few hours or it may run indefinitely, it depends on the client and the project. Other than deployment scenarios the apps would be more or less identical. As you may see from the tags, I'm assuming a message-based architecture is probably the most versatile but I'm also used to being wrong about this stuff. All suggestions and pointers welcome regarding general architectures and also specific solutions.

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  • How does one force construction of a global object in a statically linked library? [MSVC9]

    - by Peter C O Johansson
    I have a global list of function pointers. This list should be populated at startup. Order is not important and there are no dependencies that would complicate static initialization. To facilitate this, I've written a class that adds a single entry to this list in its constructor, and scatter global instances of this class via a macro where necessary. One of the primary goals of this approach is to remove the need for explicitly referencing every instance of this class externally, instead allowing each file that needs to register something in the list to do it independently. Nice and clean. However, when placing these objects in a static library, the linker discards (or rather never links in) these units because no code in them is explicitly referenced. Explicitly referencing symbols in the compilation units would be counterproductive, directly contradicting one of the main goals of the approach. For the same reason, /INCLUDE is not an acceptable option, and /OPT:NOREF is not actually related to this problem. Metrowerks has a __declspec directive for it, GCC has -force_load, but I cannot find any equivalent for MSVC.

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  • Rails original release source code

    - by user547057
    Hi, I've been looking to read some ruby code(specifically Rails) but I don't want to start with the current version of Rails since it has a lot of stuff I don't need and even more stuff that I wouldn't probably understand. I want to read only the core of Rails and supposedly the early versions were small and kind of easy to wrap one's head around(even for a neophyte like me). I have tried searching for the original release of rails, but have not been able to find it. The github repo consists of thousands of commits and I don't want to wade through those. What I want is to know whether there is any place I can get a zip or tar file with the original rails source or even the other early versions. Pointers to links will be very much appreciated. Thanks. p.s I'm new to ruby programming but not programming in general(I know a little python and scheme) and I understand blocks, lambdas and OO stuff, so I think I can tackle the rails source code. If anyone knows of other ruby projects that make for good code reading, i'd love to know of those too.

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  • Compiling Wanderlust for Windows and use it for Gmail.

    - by User1
    I'm trying to get Wanderlust working in Windows to connect to Gmail. Compiling the code is much more painful than expected. Here are the barriers so far: Can't download dependent packages: SEMI, APEL, and FLIM. I eventually found newer versions, but I'm not sure they will work. Anyone have the older versions? Needs make and install. I used MSYS and it seems to have compiled okay. SSL support. I was getting a "Cannot open load file: ssl" error. I found an ssl.el that comes with w3. So installed w3. Bash command in ssl.el: ssl-get-command is running something from /bin/sh (not a directory I have in Windows). I really don't want to refactor this code. Is there a better way? Others speak very highly of Wanderlust, so I want to give it a try. I feel like I'm almost there, but am pretty much worn out with all the crazy configuration I have to do. Does anyone have this working on Windows? I'm pretty sure it will work with Gmail, because of this post. But will it work in Windows too? If you have a few pointers, please help.

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  • C++ polymorphism, function calls

    - by moai
    Okay, I'm pretty inexperienced as a programmer, let alone in C++, so bear with me here. What I wanted to do was to have a container class hold a parent class pointer and then use polymorphism to store a child class object. The thing is that I want to call one of the child class's functions through the parent class pointer. Here's a sort of example of what I mean in code: class SuperClass { public: int x; } class SubClass : public SuperClass { public: void function1() { x += 1; } } class Container { public: SuperClass * alpha; Container(SuperClass& beta) { alpha = beta; } } int main() { Container cont = new Container(new SubClass); } (I'm not sure that's right, I'm still really shaky on pointers. I hope it gets the point across, at least.) So, I'm not entirely sure whether I can do this or not. I have a sneaking suspicion the answer is no, but I want to be sure. If someone has another way to accomplish this sort of thing, I'd be glad to hear it.

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  • C++ design related question

    - by Kotti
    Hi! Here is the question's plot: suppose I have some abstract classes for objects, let's call it Object. It's definition would include 2D position and dimensions. Let it also have some virtual void Render(Backend& backend) const = 0 method used for rendering. Now I specialize my inheritance tree and add Rectangle and Ellipse class. Guess they won't have their own properties, but they will have their own virtual void Render method. Let's say I implemented these methods, so that Render for Rectangle actually draws some rectangle, and the same for ellipse. Now, I add some object called Plane, which is defined as class Plane : public Rectangle and has a private member of std::vector<Object*> plane_objects; Right after that I add a method to add some object to my plane. And here comes the question. If I design this method as void AddObject(Object& object) I would face trouble like I won't be able to call virtual functions, because I would have to do something like plane_objects.push_back(new Object(object)); and this should be push_back(new Rectangle(object)) for rectangles and new Circle(...) for circles. If I implement this method as void AddObject(Object* object), it looks good, but then somewhere else this means making call like plane.AddObject(new Rectangle(params)); and this is generally a mess because then it's not clear which part of my program should free the allocated memory. ["when destroying the plane? why? are we sure that calls to AddObject were only done as AddObject(new something).] I guess the problems caused by using the second approach could be solved using smart pointers, but I am sure there have to be something better. Any ideas?

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  • Simple matrix example using C++ template class

    - by skyeagle
    I am trying to write a trivial Matrix class, using C++ templates in an attempt to brush up my C++, and also to explain something to a fellow coder. This is what I have som far: template class<T> class Matrix { public: Matrix(const unsigned int rows, const unsigned int cols); Matrix(const Matrix& m); Matrix& operator=(const Matrix& m); ~Matrix(); unsigned int getNumRows() const; unsigned int getNumCols() const; template <class T> T getCellValue(unsigned int row, unsigned col) const; template <class T> void setCellValue(unsigned int row, unsigned col, T value) const; private: // Note: intentionally NOT using smart pointers here ... T * m_values; }; template<class T> inline T Matrix::getCellValue(unsigned int row, unsigned col) const { } template<class T> inline void Matrix::setCellValue(unsigned int row, unsigned col, T value) { } I'm stuck on the ctor, since I need to allocate a new[] T, it seems like it needs to be a template method - however, I'm not sure I have come accross a templated ctor before. How can I implemnt the ctor?

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  • flex 4 release changes to application are not showing up.

    - by guacamoly
    I just took over a clients flex project and I can't get the app to reflect even a simple trace statement. Before I took over, the project was last successfully built using the Flash Builder Beta 2 environment/sdk. I have the latest release version of Flash Builder 4. Upon importing the project into FB4, I got a ton of errors. Most of them mostly because of the changes made to the sdk from beta2 to release. Some of the things I corrected: - mx namespace from library://ns.adobe.com/flex/halo to library://ns.adobe.com/flex/mx - video player skinning: a lot of the state names for the video player component had been changed, more required states had been added. also there were other video related component and property names that had to be updated. But I fixed all that and the application was finally able to compile (although with some warnings mostly of the duplicate variable type) The only thing now is that whatever change I make to the project doesn't get reflected in the build (debug or release). I changed existing traces, added additional traces. Nothing shows up. I even removed the applicationComplete property in the main.mxml. Everything still ran like nothing changed. Also I can't seem to debug the app. Whenever I try to debug.. flash builder says.. "Swf Application doesn't contain the required debugging information ... " Anyone have any idea how I need to even begin tackling all this? Any help or pointers would be greatly appreciated.

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  • how to minimize application downtime when updating database and application ORM

    - by yamspog
    We currently run an ecommerce solution for a leisure and travel company. Everytime we have a release, we must bring the ecommerce site down as we update database schema and the data access code. We are using a custom built ORM where each data entity is responsible for their own CRUD operations. This is accomplished by dynamically generating the SQL based on attributes in the data entity. For example, the data entity for an address would be... [tableName="address"] public class address : dataEntity { [column="address1"] public string address1; [column="city"] public string city; } So, if we add a new column to the database, we must update the schema of the database and also update the data entity. As you can expect, the business people are not too happy about this outage as it puts a crimp in their cash-flow. The operations people are not happy as they have to deal with a high-pressure time when database and applications are upgraded. The programmers are upset as they are constantly getting in trouble for the legacy system that they inherited. Do any of you smart people out there have some suggestions?

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  • How can I use a custom configured RememberMeAuthenticationFilter in spring security?

    - by Sebastian
    I want to use a slightly customized rememberme functionality with spring security (3.1.0). I declare the rememberme tag like this: <security:remember-me key="JNJRMBM" user-service-ref="gymUserDetailService" /> As I have my own rememberme service I need to inject that into the RememberMeAuthenticationFilter which I define like this: <bean id="rememberMeFilter" class="org.springframework.security.web.authentication.rememberme.RememberMeAuthenticationFilter"> <property name="rememberMeServices" ref="gymRememberMeService"/> <property name="authenticationManager" ref="authenticationManager" /> </bean> I have spring security integrated in a standard way in my web.xml: <filter-name>springSecurityFilterChain</filter-name> <filter-class>org.springframework.web.filter.DelegatingFilterProxy</filter-class> Everything works fine, except that the RememberMeAuthenticationFilter uses the standard RememberMeService, so I think that my defined RememberMeAuthenticationFilter is not being used. How can I make sure that my definition of the filter is being used? Do I need to create a custom filterchain? And if so, how can I see my current "implicit" filterchain and make sure I use the same one except my RememberMeAuthenticationFilter instead of the default one? Thanks for any advice and/or pointers!

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  • How to remove erroneous dependency from tycho build?

    - by sfinnie
    Context: Have built an eclipse update site using tycho but trying to install into target IDE fails. The update site builds fine; I can see it from a target eclipse installation and select the feature for installation. However, the dependency check fails at start of install as it can't find a declared dependency (org.eclipselabs.xtext.utils.unittesting). This shouldn't be a dependency: it was erroneously included in MANIFEST.MF for one of my eclipse plugin projects. I removed the dependency from the manifest and run mvn clean install. Build reported success. However when I try to use the newly built update site it still complains that the dependency to org.eclipselabs.xtext.utils.unittesting (a) exists and (b) can't be satisfied. So the question is: what else do I need to do to remove the dependency from the generated update site? Thanks for any pointers. PS: I know I could add the site for o.e.x.u.unittesting in the target eclipse installation so it can satisfy the dependency. However I don't want to do that; it's not needed for the feature to work and I don't want other users to have to add an unnecessary dependency.

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  • Execute a function to affect different template class instances

    - by Samer Afach
    I have a complicated problem, and I need help. I have a base case, class ParamBase { string paramValue; //... } and a bunch of class templates with different template parameters. template <typename T> class Param : public ParamBase { T value; //... } Now, each instance of Param has different template parameter, double, int, string... etc. To make it easier, I have a vector to their base class pointers that contains all the instances that have been created: vector<ParamBase*> allParamsObjects; The question is: How can I run a single function (global or member or anything, your choice), that converts all of those different instances' strings paramValue with different templates arguments and save the conversion result to the appropriate type in Param::value. This has to be run over all objects that are saved in the vector allParamsObjects. So if the template argument of the first Param is double, paramValue has to be converted to double and saved in value; and if the second Param's argument is int, then the paramValue of the second has to be converted to int and saved in value... etc. I feel it's almost impossible... Any help would be highly appreciated :-)

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  • How to take html markup from a string and escape it to work within a script?

    - by zac
    I am using wordpress as a CMS and trying to allow user fields to be input to populate the info windows in a Google Map script. I am using this to select the id and pull in the content from a custom field : $post_id = 222; $my_post = get_post($post_id); $snip = get_post_meta($post_id, 'custom-field', true); $permalink = get_permalink( $post_id ); $pass_to = '<div class="content">'.$snip.'</div><div class="moreLink"><a href="'.$permalink.'">Find out more » </a></div></div>'; var point = new GLatLng('<?php echo $lat; $lat; ?>','<?php echo $long; $long; ?>'); var marker = createMarker(point,"<?php echo $mapTitle; $mapTitle; ?>", '<?php echo $pass_to; ?>') map.addOverlay(marker); It works fine unless there is any html in the custom-field which breaks the script. I looked at htmlspcialchar and htmlentities but rather than strip everything out I would like to have it escaped so it still works and the html is intact. Any suggestions? I am pretty new to PHP and would really appreciate any pointers.

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  • Enterprise integration of disparate systems

    - by Chris Latta
    We're about to embark on a fairly large integration effort to kill off a bunch of Access and Sql Server databases and get everything into one coherent enterprise system. There are also a number of other systems (accounting, CRM, payroll, MS Exchange) that hold critical data that we need to integrate (use for data validation in other systems), report on and otherwise expose. It is likely that some of these systems will change in the next few years, so we need to isolate our systems to be ready for change. Ideally we would be able to expose our forms in a consistent manner across as many of our our systems as possible without having to re-develop them for each system. We are currently targeting SharePoint (2007 and soon 2010), Office (2007 and soon 2010 - Word, Excel, PowerPoint and Outlook), Reporting Services, .Net console applications, .Net Windows applications, shell extensions, and with the possibility of exposing some functionality on mobile devices (BlackBerries currently, maybe iPhones later) and via our website. We're moving development to Visual Studio 2010 (from 2005) ahead of migrating to SharePoint 2010 and Office 2010. Given that most of our development is presently targeted to the .Net framework (mostly in C#) it seems logical to stick with this unless there is some compelling reason to switch frameworks/platform for some aspects. We're thinking of your standard Database-Data Integration layer-Business Objects Layer-Web Services (or REST) layer-Client Application plus doing our own client application with WPF (or something else?) forms that can also be exposed in the MS systems (SharePoint, Office, Windows). So, we don't want much, just everything :) Basically we need to isolate ourselves from database and systems changes, create an API that can be used throughout our systems and then make this functionality available in our client applications. I'm very keen to get pointers from anyone who has tips on how to pull this off. Should we look at the Enterprise Library as a place to start? Is REST with ASP.Net MVC2 a better solution than Web Services for a system like this? Will WPF deliver forms re-use or is there something better?

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  • Improving File Read Performance (single file, C++, Windows)

    - by david
    I have large (hundreds of MB or more) files that I need to read blocks from using C++ on Windows. Currently the relevant functions are: errorType LargeFile::read( void* data_out, __int64 start_position, __int64 size_bytes ) const { if( !m_open ) { // return error } else { seekPosition( start_position ); DWORD bytes_read; BOOL result = ReadFile( m_file, data_out, DWORD( size_bytes ), &bytes_read, NULL ); if( size_bytes != bytes_read || result != TRUE ) { // return error } } // return no error } void LargeFile::seekPosition( __int64 position ) const { LARGE_INTEGER target; target.QuadPart = LONGLONG( position ); SetFilePointerEx( m_file, target, NULL, FILE_BEGIN ); } The performance of the above does not seem to be very good. Reads are on 4K blocks of the file. Some reads are coherent, most are not. A couple questions: Is there a good way to profile the reads? What things might improve the performance? For example, would sector-aligning the data be useful? I'm relatively new to file i/o optimization, so suggestions or pointers to articles/tutorials would be helpful.

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  • Who deletes the copied instance in + operator ? (c++)

    - by Dima
    Hello, I searched how to implement + operator properly all over the internet and all the results i found do the following steps : const MyClass MyClass::operator+(const MyClass &other) const { MyClass result = *this; // Make a copy of myself. Same as MyClass result(*this); result += other; // Use += to add other to the copy. return result; // All done! } I have few questions about this "process" : Isn't that stupid to implement + operator this way, it calls the assignment operator(which copies the class) in the first line and then the copy constructor in the return (which also copies the class , due to the fact that the return is by value, so it destroys the first copy and creates a new one.. which is frankly not really smart ... ) When i write a=b+c, the b+c part creates a new copy of the class, then the 'a=' part copies the copy to himself. who deletes the copy that b+c created ? Is there a better way to implement + operator without coping the class twice, and also without any memory issues ? thanks in advance

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  • How can I do something when a runloop event is done processing?

    - by quixoto
    I have some processing in my Cocoa app that sometimes ends up calling through a hierarchy of data to do a bunch of work as the result of an event. Each small piece creates and destroys some resources. I don't want those resources around most of the time, but I would like to find a smart way of creating them before all the work and killing them at the end. Short of making those buffers etc available globally from the "parent" or elsewhere, is there a way to know locally in some code when an event loop run has ended? Then I could create them if they're not there, and keep them until the run loop ends, reusing them for any subsequent calls before that time. EDIT: I'm not looking for suggestions on how to restructure my code, which I may do anyways. This issue just brought up the question for me of how to know when the runloop is done. If I were writing in, I dunno, Javascript, I'd use a setTimeout with zero to accomplish end-event cleanup. I suppose an NSTimer with an interval of zero might accomplish this too, but wondering if there's something cleaner. Thanks.

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  • wrap from last screen to first screen in android Launcher2

    - by poboy975
    hi, I'm learning java and android. and I've been looking at trying to wrap the last screen to the first screen in the android Launcher2. I've tried googleing, and searching here, but there really isnt much information about the launcher2 source...I've been modifying the workspace.java file, but there has been minimal effect. no wrap around so far...I have not been able to find a .xml file that also might control the hard stop when you reach the end of the screens. I'll give a small example of the code that i have been modifying. original code: public void scrollRight() { clearVacantCache(); if (mNextScreen == INVALID_SCREEN && mCurrentScreen < getChildCount() -1 && mScroller.isFinished()) { snapToScreen(mCurrentScreen + 1); } modified code: public void scrollRight() { clearVacantCache(); if (mNextScreen == INVALID_SCREEN && mCurrentScreen < getChildCount() -1 && mScroller.isFinished()) { snapToScreen(mCurrentScreen + 1); }if (mCurrentScreen == getChildCount() -1 && mScroller.isFinished()) { snapToScreen(0); I would appreciate any tips or pointers if anyone has an idea where i'm going wrong, or someplace i can search to get the answers. the code looks to me like it should work, but I'm probably missing something obvious.

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