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  • Function matching in Qt

    - by Alexander
    Hello, I have some trouble with Qt. I have a class 'Core' class Core { public: static QString get_file_content(QString filename); static void setMainwindow(MainWindow *w); private: static MainWindow *main_window; }; and class 'MainWindow' in namespace Ui: namespace Ui { class MainWindow; } class MainWindow : public QMainWindow { Q_OBJECT public: MainWindow(QWidget *parent = 0); ~MainWindow(); private: Ui::MainWindow *ui; }; In MainWindow constructor I make MainWindow::MainWindow(QWidget *parent) : QMainWindow(parent), ui(new Ui::MainWindow) { ui->setupUi(this); Core::setMainwindow(this); } and gets error mainwindow.cpp:8: error: no matching function for call to 'Core::setMainwindow(MainWindow* const)' Of cource, i include core.h with declaration of 'Core' class. That's occurs only on setMainwindow method. So the questions is - why Core class method setMainwindow() is invisible in MainWindow class?

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  • .NET MVC - Storing database result during single page result?

    - by ropstah
    Fairly simple issue which is solved in PHP by using a static variable. private static $pages; public function Pages() { if($pages == null) { $pages = new PageCollection(); $pages->findAll(); } } Everywhere in my code I use Pages()::someFindFunction() to make sure the results are fetched only once, and I use that same collection. I want the same in my .NET MVC application: use something like: <%=MySite.Pages.findById(1).Title%> In the code below, if I use a private variable, or if I use a public class with shared variables (doesn't matter) they are both persisted during the entire application. I want them to load the same way PHP does, once per request. Now where do I store the .NET equivalent of private static $pages, so that the code below works? //what to do with $pages?? Public Module MySite Public Function Pages() As PageCollection If $pages Is Nothing Then $pages.loadAll() End If Return $pages End Function End Module

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  • How to implement Cocoa copyWithZone on derived object in MonoMac C#?

    - by Justin Aquadro
    I'm currently porting a small Winforms-based .NET application to use a native Mac front-end with MonoMac. The application has a TreeControl with icons and text, which does not exist out of the box in Cocoa. So far, I've ported almost all of the ImageAndTextCell code in Apple's DragNDrop example: https://developer.apple.com/library/mac/#samplecode/DragNDropOutlineView/Listings/ImageAndTextCell_m.html#//apple_ref/doc/uid/DTS40008831-ImageAndTextCell_m-DontLinkElementID_6, which is assigned to an NSOutlineView as a custom cell. It seems to be working almost perfectly, except that I have not figured out how to properly port the copyWithZone method. Unfortunately, this means the internal copies that NSOutlineView is making do not have the image field, and it leads to the images briefly vanishing during expand and collapse operations. The objective-c code in question is: - (id)copyWithZone:(NSZone *)zone { ImageAndTextCell *cell = (ImageAndTextCell *)[super copyWithZone:zone]; // The image ivar will be directly copied; we need to retain or copy it. cell->image = [image retain]; return cell; } The first line is what's tripping me up, as MonoMac does not expose a copyWithZone method, and I don't know how to otherwise call it. Update Based on current answers and additional research and testing, I've come up with a variety of models for copying an object. static List<ImageAndTextCell> _refPool = new List<ImageAndTextCell>(); // Method 1 static IntPtr selRetain = Selector.GetHandle ("retain"); [Export("copyWithZone:")] public virtual NSObject CopyWithZone(IntPtr zone) { ImageAndTextCell cell = new ImageAndTextCell() { Title = Title, Image = Image, }; Messaging.void_objc_msgSend (cell.Handle, selRetain); return cell; } // Method 2 [Export("copyWithZone:")] public virtual NSObject CopyWithZone(IntPtr zone) { ImageAndTextCell cell = new ImageAndTextCell() { Title = Title, Image = Image, }; _refPool.Add(cell); return cell; } [Export("dealloc")] public void Dealloc () { _refPool.Remove(this); this.Dispose(); } // Method 3 static IntPtr selRetain = Selector.GetHandle ("retain"); [Export("copyWithZone:")] public virtual NSObject CopyWithZone(IntPtr zone) { ImageAndTextCell cell = new ImageAndTextCell() { Title = Title, Image = Image, }; _refPool.Add(cell); Messaging.void_objc_msgSend (cell.Handle, selRetain); return cell; } // Method 4 static IntPtr selRetain = Selector.GetHandle ("retain"); static IntPtr selRetainCount = Selector.GetHandle("retainCount"); [Export("copyWithZone:")] public virtual NSObject CopyWithZone (IntPtr zone) { ImageAndTextCell cell = new ImageAndTextCell () { Title = Title, Image = Image, }; _refPool.Add (cell); Messaging.void_objc_msgSend (cell.Handle, selRetain); return cell; } public void PeriodicCleanup () { List<ImageAndTextCell> markedForDelete = new List<ImageAndTextCell> (); foreach (ImageAndTextCell cell in _refPool) { uint count = Messaging.UInt32_objc_msgSend (cell.Handle, selRetainCount); if (count == 1) markedForDelete.Add (cell); } foreach (ImageAndTextCell cell in markedForDelete) { _refPool.Remove (cell); cell.Dispose (); } } // Method 5 static IntPtr selCopyWithZone = Selector.GetHandle("copyWithZone:"); [Export("copyWithZone:")] public virtual NSObject CopyWithZone(IntPtr zone) { IntPtr copyHandle = Messaging.IntPtr_objc_msgSendSuper_IntPtr(SuperHandle, selCopyWithZone, zone); ImageAndTextCell cell = new ImageAndTextCell(copyHandle) { Image = Image, }; _refPool.Add(cell); return cell; } Method 1: Increases the retain count of the unmanaged object. The unmanaged object will persist persist forever (I think? dealloc never called), and the managed object will be harvested early. Seems to be lose-lose all-around, but runs in practice. Method 2: Saves a reference of the managed object. The unmanaged object is left alone, and dealloc appears to be invoked at a reasonable time by the caller. At this point the managed object is released and disposed. This seems reasonable, but on the downside the base type's dealloc won't be run (I think?) Method 3: Increases the retain count and saves a reference. Unmanaged and managed objects leak forever. Method 4: Extends Method 3 by adding a cleanup function that is run periodically (e.g. during Init of each new ImageAndTextCell object). The cleanup function checks the retain counts of the stored objects. A retain count of 1 means the caller has released it, so we should as well. Should eliminate leaking in theory. Method 5: Attempt to invoke the copyWithZone method on the base type, and then construct a new ImageAndTextView object with the resulting handle. Seems to do the right thing (the base data is cloned). Internally, NSObject bumps the retain count on objects constructed like this, so we also use the PeriodicCleanup function to release these objects when they're no longer used. Based on the above, I believe Method 5 is the best approach since it should be the only one that results in a truly correct copy of the base type data, but I don't know if the approach is inherently dangerous (I am also making some assumptions about the underlying implementation of NSObject). So far nothing bad has happened "yet", but if anyone is able to vet my analysis then I would be more confident going forward.

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  • Defining a dd/mm/yyyy field within an abstract table model

    - by Simon Andi
    I have defined an abstract table model but one of the columns should house date values as dd/mm/yyyy format not sure how to do this. I have a external global file and have hard coded the dates as dd/mm/yyyy. How can I define this column within my abstract table model so that to only allow only dates having dd/mm/yyyy format. public class OptraderGlobalParameters { public static boolean DEBUG = true; //Set DEBUG = true for Debugging /*=========================*/ /*Table Array For Dividends*/ /*=========================*/ public static String[] columnNames = {"Date", "Dividend", "Actual", "Yield (%)" }; public static Object[][] data = { {"dd/mm/yyyy", new Double(5), new Boolean(false), new Boolean(false)}, {"dd/mm/yyyy", new Double(5), new Boolean(false), new Boolean(false)}, {"dd/mm/yyyy", new Double(5), new Boolean(false), new Boolean(false)}, {"dd/mm/yyyy", new Double(5), new Boolean(false), new Boolean(false)}, {"dd/mm/yyyy", new Double(5), new Boolean(false), new Boolean(false)}, }; }

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  • Error when trying to use hibernate annotations.

    - by Wilhelm
    The error I'm receiving is listed here. That's my HibernateUtil.java package com.rosejapan; import org.hibernate.SessionFactory; import org.hibernate.cfg.AnnotationConfiguration;; public class HibernateUtil { private static final SessionFactory sessionFactory; static { try { // Create the SessionFactory from hibernate.cfg.xml sessionFactory = new AnnotationConfiguration().configure().buildSessionFactory(); } catch(Throwable e) { System.err.println("Initial sessionFactory creation failed. " + e); throw new ExceptionInInitializerError(e); } } public static SessionFactory getSessionFactory() { return sessionFactory; } } Everything looks all right... I've already included log4j-boot.jar in the CLASSPATH, but didn't resolved my problem.

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  • Animation in quartz 2D

    - by coure06
    I want to create an app which after each 1 second will show 4-5 words on screen but the last word will zoom out/in. I can easily create static words and for the last animating word i need to draw the static again n again. How can i create 2 separate layers so the static text is on one layer ( i will fill it after each second) and the last word (animated one) will be on other layer. How to create 2 separate layers? Attached on same screen but handling their drawRect method separately?

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  • Why .NET Boolean has TrueLiteral and TrueString?

    - by user309937
    Why in Boolean type there are two fields with the same value? internal const int True = 1; internal const int False = 0; internal const string TrueLiteral = "True"; internal const string FalseLiteral = "False"; and public static readonly string TrueString; public static readonly string FalseString; static Boolean() { TrueString = "True"; FalseString = "False"; } in reflector generated code, methods don't use those strings but: public string ToString(IFormatProvider provider) { if (!this) { return "False"; } return "True"; } would't it be better to use those const values?

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  • Is this a correct Interlocked synchronization design?

    - by Dan Bryant
    I have a system that takes Samples. I have multiple client threads in the application that are interested in these Samples, but the actual process of taking a Sample can only occur in one context. It's fast enough that it's okay for it to block the calling process until Sampling is done, but slow enough that I don't want multiple threads piling up requests. I came up with this design (stripped down to minimal details): public class Sample { private static Sample _lastSample; private static int _isSampling; public static Sample TakeSample(AutomationManager automation) { //Only start sampling if not already sampling in some other context if (Interlocked.CompareExchange(ref _isSampling, 0, 1) == 0) { try { Sample sample = new Sample(); sample.PerformSampling(automation); _lastSample = sample; } finally { //We're done sampling _isSampling = 0; } } return _lastSample; } private void PerformSampling(AutomationManager automation) { //Lots of stuff going on that shouldn't be run in more than one context at the same time } } Is this safe for use in the scenario I described?

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  • Any way to use a class extension method to support an interface method in C#?

    - by dudeNumber4
    Console app below compiles, but the interface cast fails at run time. Is there an easy way to make this work? namespace ConsoleApplication1 { class Monkey { public string Shock { get { return "Monkey has been shocked."; } } } static class MonkeyExtensionToSupportIWombat { public static string ShockTheMonkey( this Monkey m ) { return m.Shock; } } interface IWombat { string ShockTheMonkey(); } class Program { static void Main( string[] args ) { var monkey = new Monkey(); Console.WriteLine( "Shock the monkey without the interface: {0}", monkey.Shock ); IWombat wombat = monkey as IWombat; Console.WriteLine( "Shock the monkey with the interface: {0}", wombat.ShockTheMonkey() ); Console.ReadLine(); } } }

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  • How to make this code compile?

    - by skydoor
    // File: foo.c static int var; void foo() { var++; } // end of file foo.c // File bar.c: static int var; void bar() { var++; } // end of file bar.c // file main.c static int var; void main() { foo(); bar(); printf("%d", var); } // end of file main.c Question: Will the above program compile ? If so what will be the result ? I tested the code and found it couldn't be compiled. I try to use extern in main.c to use the function foo() and bar() but it still couldn't be compiled.

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  • Local variables in java

    - by Mandar
    Hello , I went through local variables and class variables concept. But I had stuck at a doubt " Why is it so that we cannot declare local variables as static " ? For e.g Suppose we have a play( ) function : void play( ) { static int i=5; System.out.println(i); } It gives me error in eclipse : Illegal modifier for parameter i; I had this doubt because of the following concepts I have read : Variables inside method : scope is local i.e within that method. When variable is declared as static , it is present for the entire class i.e not to particular object. Please could anyone help me out to clarify the concept. Thanks.

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  • question about polynomial multiplication

    - by davit-datuashvili
    i know that horners method for polynomial pultiplication is faster but here i dont know what is happening here is code public class horner{ public static final int n=10; public static final int x=7; public static void main(String[] args){ //non fast version int a[]=new int[]{1,2,3,4,5,6,7,8,9,10}; int xi=1; int y=a[0]; for (int i=1;i<n;i++){ xi=x*xi; y=y+a[i]*xi; } System.out.println(y); //fast method int y1=a[n-1]; for (int i=n-2;i>=0;i--){ y1=x*y+a[i]; } System.out.println(y1); } } result of this two methods are not same result of first method is 462945547 and result of second method is -1054348465 please help

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  • Why isn't Xcode building a file in my project

    - by richcollins
    I have a static library project that I inherited from another developer. I added a class to the project and built it. When I include the static lib in another project, the build fails with a symbol not found error for the class that I added. I looked at the build logs for the static lib project and I noticed that the .m file isn't compiled. The file is clearly visible in Xcode, right next to all of the other class files. Can anyone think of a reason that the file wouldn't be built? How does Xcode discover the files that it builds?

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  • What causes my borderless C++/CLI app to crash when overriding WndProc?

    - by Ste
    I use a form with border NONE. I need to override WndProc for resize and move form. However, using this code, my app crashes! static const int WM_NCHITTEST = 0x0084; static const int HTCLIENT = 1; static const int HTCAPTION = 2; protected: virtual void Form1::WndProc(System::Windows::Forms::Message %m) override { switch (m.Msg) { case WM_NCHITTEST: if (m.Result == IntPtr(HTCLIENT)) { m.Result = IntPtr(HTCAPTION); } break; } Form1::WndProc(m); } virtual System::Windows::Forms::CreateParams^ get() override { System::Windows::Forms::CreateParams^ cp = __super::CreateParams; cp->Style |= 0x40000; return cp; } How can I fix my code not to crash but still allow my form to be moved and resized?

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  • When i close window cookies are destroying in flex

    - by praveen
    Hi, I am using external interface to store cookies in client side of application. Like I have created a cookie in html and i am using those methods in flex using External Interface. I am saving a username in cookie when I re use cookie is displaying, I have deployed in server and i ran like http://localhost/[Path]/index.html.in this html I am embedded swf file and I have saved cookie in html JavaScript, now if I open this url cookie is saving if I open a new window what ever the cookies are a raised and it is loading from start. for cookies saving i am using this code in flex:`package Name{ import flash.external.ExternalInterface; /** * The Cookie class provides a simple way to create or access * cookies in the embedding HTML document of the application. * */ public class Cookies { /** * Flag if the class was properly initialized. */ private static var _initialized:Boolean = false; /** * Name of the cookie. */ private var _name:String; /** * Contents of the cookie. */ private var _value:String; /** * Flag indicating if a cookie was just created. It is <code>true</code> * when the cookie did not exist before and <code>false</code> otherwise. */ private var _isNew:Boolean; /** * Name of the external javascript function used for getting * cookie information. */ private static const GET_COOKIE:String = "cookieGetCookie"; /** * Name of the external javascript function used for setting * cookie information. */ private static const SET_COOKIE:String = "cookieSetCookie"; /** * Javascript code to define the GET_COOKIE function. */ private static var FUNCTION_GET_COOKIE:String = "function () { " + "if (document." + GET_COOKIE + " == null) {" + GET_COOKIE + " = function (name) { " + "if (document.cookie) {" + "cookies = document.cookie.split('; ');" + "for (i = 0; i < cookies.length; i++) {" + "param = cookies[i].split('=', 2);" + "if (decodeURIComponent(param[0]) == name) {" + "value = decodeURIComponent(param[1]);" + "return value;" + "}" + "}" + "}" + "return null;" + "};" + "}" + "}"; /** * Javascript code to define the SET_COOKIE function. */ private static var FUNCTION_SET_COOKIE:String = "function () { " + "if (document." + SET_COOKIE + " == null) {" + SET_COOKIE + " = function (name, value) { " + "document.cookie = name + '=' + value;" + "};" + "}" + "}"; /** * Initializes the class by injecting javascript code into * the embedding document. If the class was already initialized * before, this method does nothing. */ private static function initialize():void { if (Cookies._initialized) { return; } if (!ExternalInterface.available) { throw new Error("ExternalInterface is not available in this container. Internet Explorer ActiveX, Firefox, Mozilla 1.7.5 and greater, or other browsers that support NPRuntime are required."); } // Add functions to DOM if they aren't already there ExternalInterface.call(FUNCTION_GET_COOKIE); ExternalInterface.call(FUNCTION_SET_COOKIE); Cookies._initialized = true; } /** * Creates a new Cookie object. If a cookie with the specified * name already exists, the existing value is used. Otherwise * a new cookie is created as soon as a value is assigned to it. * * @param name The name of the cookie */ public function Cookies(name:String) { Cookies.initialize(); this._name = name; this._value = ExternalInterface.call(GET_COOKIE, name) as String; this._isNew = this._value == null; } /** * The name of the cookie. */ public function get name():String { return this._name; } /** * The value of the cookie. If it is a new cookie, it is not * made persistent until a value is assigned to it. */ public function get value():String { return this._value; } /** * @private */ public function set value(value:String):void { this._value = value; ExternalInterface.call(SET_COOKIE, this._name, this._value); } /** * The <code>isNew</code> property indicates if the cookie * already exists or not. */ public function get isNew():Boolean { return this._isNew; } } } I am using cookie like thisvar anotherCookie:Cookies = new Cookies("username"); anotherCookie.value=[Textinput].text;`.is there any code i need to use save cookie in new window also? Please help me Thanks in Advance.

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  • The best way to assign an immutable instance to a Collection in Java

    - by Ali
    Today I was reading through some Hibernate code and I encounter something interesting. There is a class called CollectionHelper that defines the following constant varibale: public final class CollectionHelper { public static final List EMPTY_LIST = Collections.unmodifiableList( new ArrayList(0 ) ; public static final Collection EMPTY_COLLECTION = Collections.unmodifiableCollection(new ArrayList(0) ); public static final Map EMPTY_MAP = Collections.unmodifiableMap( new HashMap(0) ); They have used these constants to initialize collections with immutable instances. Why they didn't simply use the Collections.EMPTY_LIST for initializing lists? Is there a benefit in using the following method?

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  • Syntax error in SWIG using __thread keyword

    - by user366838
    I am trying to make some code thread safe for use with pthreads. This code is written in C++, but is linked to using SWIG. g++ compiles this correctly, but when swig tries to create a wrapper, I get: fast_alloc.hh:109: Error: Syntax error in input(3) The original, unsafe code that compiles correctly is: static void *freeLists[Num_Buckets]; and the error occurs when I change it to: static __thread void *freeLists[Num_Buckets]; I have made other parts thread safe adding "__thread", for example, this works: static __thread unsigned newCount[Num_Buckets];

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  • How to connect to a network of activemq brokers from a client application?

    - by subh
    I have setup a network of brokers in activemq, how do i connect to that from my client application I tried with network:static:(tcp://master1.IP:61616,tcp://master2.IP:61617) and but I get the following exception javax.jms.JMSException: Uncategorized exception occured during JMS processing; nested exception is javax.jms.JMSException: Could not create Transport. Reason: java.io.IOException: Transport scheme NOT recognized: [network]; With static:(tcp://master1.IP:61616,tcp://master2.IP:61617) I get exception javax.jms.JMSException: Uncategorized exception occured during JMS processing; nested exception is javax.jms.JMSException: Could not create Transport. Reason: java.io.IOException: Transport scheme NOT recognized: [static]; Thanks

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  • What causes my borderless C++ app to crash when overriding WndProc?

    - by Ste
    I use a form with border NONE. I need to override WndProc for resize and move form. However, using this code, my app crashes! static const int WM_NCHITTEST = 0x0084; static const int HTCLIENT = 1; static const int HTCAPTION = 2; protected: virtual void Form1::WndProc(System::Windows::Forms::Message %m) override { switch (m.Msg) { case WM_NCHITTEST: if (m.Result == IntPtr(HTCLIENT)) { m.Result = IntPtr(HTCAPTION); } break; } Form1::WndProc(m); } virtual System::Windows::Forms::CreateParams^ get() override { System::Windows::Forms::CreateParams^ cp = __super::CreateParams; cp->Style |= 0x40000; return cp; } How can I fix my code not to crash but still allow my form to be moved and resized?

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  • htaccess rewriterule

    - by user322731
    I currently have this rule where I want the page to just render my static content. RewriteRule ^videos\/coverage\/view\/236159\-([0-9a-zA-Z-]+) http: //website.com/static/236159.html [NC] However, this doesn't work. It works with a L tag but then the URL is different: RewriteRule ^videos\/coverage\/view\/236159\-([0-9a-zA-Z-]+) http: //website.com/static/236159.html [L, NC] My goal is to keep the URL the same but the content different. Can anyone point out to what flags are needed in order to get this working properly? Thanks!

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  • Deserialize Stream to List<T> or any other type

    - by Sam
    Attempting to deserialize a stream to List<T> (or any other type) and am failing with the error: The type arguments for method 'Foo.Deserialize<T>(System.IO.Stream)' cannot be inferred from the usage. Try specifying the type arguments explicitly. This fails: public static T Deserialize<T>(this Stream stream) { BinaryFormatter bin = new BinaryFormatter(); return (T)bin.Deserialize(stream); } But this works: public static List<MyClass.MyStruct> Deserialize(this Stream stream) { BinaryFormatter bin = new BinaryFormatter(); return (List<MyClass.MyStruct>)bin.Deserialize(stream); } or: public static object Deserialize(this Stream stream) { BinaryFormatter bin = new BinaryFormatter(); return bin.Deserialize(stream); } Is it possible to do this without casting, e.g. (List<MyStruct>)stream.Deserialize()?

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  • Dynamically register constructor methods in an AbstractFactory at compile time using C++ templates

    - by Horacio
    When implementing a MessageFactory class to instatiate Message objects I used something like: class MessageFactory { public: static Message *create(int type) { switch(type) { case PING_MSG: return new PingMessage(); case PONG_MSG: return new PongMessage(); .... } } This works ok but every time I add a new message I have to add a new XXX_MSG and modify the switch statement. After some research I found a way to dynamically update the MessageFactory at compile time so I can add as many messages as I want without need to modify the MessageFactory itself. This allows for cleaner and easier to maintain code as I do not need to modify three different places to add/remove message classes: #include <stdio.h> #include <stdlib.h> #include <string.h> #include <inttypes.h> class Message { protected: inline Message() {}; public: inline virtual ~Message() { } inline int getMessageType() const { return m_type; } virtual void say() = 0; protected: uint16_t m_type; }; template<int TYPE, typename IMPL> class MessageTmpl: public Message { enum { _MESSAGE_ID = TYPE }; public: static Message* Create() { return new IMPL(); } static const uint16_t MESSAGE_ID; // for registration protected: MessageTmpl() { m_type = MESSAGE_ID; } //use parameter to instanciate template }; typedef Message* (*t_pfFactory)(); class MessageFactory· { public: static uint16_t Register(uint16_t msgid, t_pfFactory factoryMethod) { printf("Registering constructor for msg id %d\n", msgid); m_List[msgid] = factoryMethod; return msgid; } static Message *Create(uint16_t msgid) { return m_List[msgid](); } static t_pfFactory m_List[65536]; }; template <int TYPE, typename IMPL> const uint16_t MessageTmpl<TYPE, IMPL >::MESSAGE_ID = MessageFactory::Register( MessageTmpl<TYPE, IMPL >::_MESSAGE_ID, &MessageTmpl<TYPE, IMPL >::Create); class PingMessage: public MessageTmpl < 10, PingMessage > {· public: PingMessage() {} virtual void say() { printf("Ping\n"); } }; class PongMessage: public MessageTmpl < 11, PongMessage > {· public: PongMessage() {} virtual void say() { printf("Pong\n"); } }; t_pfFactory MessageFactory::m_List[65536]; int main(int argc, char **argv) { Message *msg1; Message *msg2; msg1 = MessageFactory::Create(10); msg1->say(); msg2 = MessageFactory::Create(11); msg2->say(); delete msg1; delete msg2; return 0; } The template here does the magic by registering into the MessageFactory class, all new Message classes (e.g. PingMessage and PongMessage) that subclass from MessageTmpl. This works great and simplifies code maintenance but I still have some questions about this technique: Is this a known technique/pattern? what is the name? I want to search more info about it. I want to make the array for storing new constructors MessageFactory::m_List[65536] a std::map but doing so causes the program to segfault even before reaching main(). Creating an array of 65536 elements is overkill but I have not found a way to make this a dynamic container. For all message classes that are subclasses of MessageTmpl I have to implement the constructor. If not it won't register in the MessageFactory. For example commenting the constructor of the PongMessage: class PongMessage: public MessageTmpl < 11, PongMessage > { public: //PongMessage() {} /* HERE */ virtual void say() { printf("Pong\n"); } }; would result in the PongMessage class not being registered by the MessageFactory and the program would segfault in the MessageFactory::Create(11) line. The question is why the class won't register? Having to add the empty implementation of the 100+ messages I need feels inefficient and unnecessary.

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  • PHP OOP: Method Chaining

    - by Isis
    I have the following code, <?php class Templater { static $params = array(); public static function assign($name, $value) { self::$params[] = array($name => $value); } public static function draw() { self::$params; } } $test = Templater::assign('key', 'value'); $test = Templater::draw(); print_r($test); How can I alter this script so I could use this? $test = Templater::assign('key', 'value')->assign('key2', 'value2')->draw(); print_r($test);

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  • Getting 'this' pointer inside dependency property changed callback

    - by mizipzor
    I have the following dependency property inside a class: class FooHolder { public static DependencyProperty CurrentFooProperty = DependencyProperty.Register( "CurrentFoo", typeof(Foo), typeof(FooHandler), new PropertyMetadata(OnCurrentFooChanged)); private static void OnCurrentFooChanged(DependencyObject d, DependencyPropertyChangedEventArgs e) { FooHolder holder = (FooHolder) d.Property.Owner; // <- something like this // do stuff with holder } } I need to be able to retrieve a reference to the class instance in which the changed property belongs. This is since FooHolder has some event handlers that needs to be hooked/unhooked when the value of the property is changed. The property changed callback must be static, but the event handler is not.

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  • How to manage db connections on server?

    - by simpatico
    I have a severe problem with my database connection in my web application. Since I use a single database connection for the whole application from singleton Database class, if i try concurrent db operations (two users) the database rollsback the transactions. This is my static method used: All threads/servlets call static Database.doSomething(...) methods, which in turn call the the below method. private static /* synchronized*/ Connection getConnection(final boolean autoCommit) throws SQLException { if (con == null) { con = new MyRegistrationBean().getConnection(); } con.setAutoCommit(true); //TODO return con; } What's the recommended way to manage this db connection/s I have, so that I don't incurr in the same problem.

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