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• Link Error : xxx is already defined in *****.LIB :: What exactly is wrong?

  - by claws

  Problem: I'm trying to use a library named DCMTK which used some other external libraries ( zlib, libtiff, libpng, libxml2, libiconv ). I've downloaded these external libraries (*.LIB & *.h files ) from the same website. Now, when I compile the DCMTK library I'm getting link errors (793 errors) like this: Error 2 error LNK2005: __encode_pointer already defined in MSVCRTD.lib(MSVCR90D.dll) LIBCMTD.lib dcmmkdir Error 3 error LNK2005: __decode_pointer already defined in MSVCRTD.lib(MSVCR90D.dll) LIBCMTD.lib dcmmkdir Error 4 error LNK2005: __CrtSetCheckCount already defined in MSVCRTD.lib(MSVCR90D.dll) LIBCMTD.lib dcmmkdir Error 5 error LNK2005: __invoke_watson already defined in MSVCRTD.lib(MSVCR90D.dll) LIBCMTD.lib dcmmkdir Error 6 error LNK2005: __errno already defined in MSVCRTD.lib(MSVCR90D.dll) LIBCMTD.lib dcmmkdir Error 7 error LNK2005: __configthreadlocale already defined in MSVCRTD.lib(MSVCR90D.dll) LIBCMTD.lib dcmmkdir Error 8 error LNK2005: _exit already defined in MSVCRTD.lib(MSVCR90D.dll) LIBCMTD.lib dcmmkdir Documentation: This seems to be a popular error for this library so, they do have a FAQ entry addressing this issue which ( http://forum.dcmtk.org/viewtopic.php?t=35 ) says: The problem is that the linker tries to combine different, incompatible versions of the Visual C++ runtime library into a single binary. This happens when not all parts of your project and the libraries you link against are generated with the same code generation options in Visual C++. Do not use the /NODEFAULTLIB workaround, because strange software crashes may follow. Fix the problem! DCMTK is by default compiled with the "Multithreaded" or "Multithreaded Debug" code generation option (the latter for Debug mode). Either change the project settings of all of your code to use these code generation options, or change the code generation for all DCMTK modules and re-compile. MFC users beware: DCMTK should be compiled with "Multithreaded DLL" or "Multithreaded DLL Debug" settings if you want to link the libraries into an MFC application. Solution to same problem for others: http://stackoverflow.com/questions/2259697/vscopengl-huge-amount-of-linker-issues-with-release-build-only says: It seems that your release build is trying to link to something that was built debug. You probably have a broken dependency in your build, (or you missed rebuilding something to release by hand if your project is normally built in pieces). More technically, you seem to be linking projects built with different C Run Time library settings, one with "Multi-Threaded", another one with "Multi-Threaded Debug". Adjust the settings for all the projects to use the very same flavour of the library and the issue should go away Questions: Till now I used to think that Name mangling is the only problem that may cause linking failures if its not been standardized. Just now I knew there are other things also which can cause same effect. Whats up with the "Debug Mode" (Multi-Threaded Debug) and "Release Mode" (Multi-Threaded)? What exactly is happening under the hood? Why exactly this thing is causing linking error? I wonder if there is something called "Single-Threaded Debug" and "Single-Threaded" which again causes the same thing. Documentation talks something about "Code Generation Options". What Code Generation Options? WTH are they? Documentation specifically warns us not to use /NODEFAULTLIB workaround. (example /NODEFAULTLIB :msvcrt ). Why? How would I cause troubles? what exactly is it? Please explain the last point in the documentation for MFC users. Because I'm going to use MFC later in this project. Explain Why should we do it? What troubles would it cause if I don't. Anything more you'd like to mention? I mean regarding similar errors. I'm very interested in Linker & its problems. So, if there are any similar things you can mentions them or some keywords atleast.

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• How to take advantage of an auto-property when refactoring this .Net 1.1 sample?

  - by Hamish Grubijan

  I see a lot of legacy .Net 1.1-style code at work like in example below, which I would like to shrink with the help of an auto-property. This will help many classes shrink by 30-40%, which I think would be good. public int MyIntThingy { get { return _myIntThingy; } set { _myIntThingy = value; } } private int _myIntThingy = -1; This would become: public int MyIntThingy { get; set; } And the only question is - where do I set MyIntThingy = -1;? If I wrote the class from the start, then I would have a better idea, but I did not. An obvious answer would be: put it in the constructor. Trouble is: there are many constructors in this class. Watching the initialization to -1 in the debugger, I see it happen (I believe) before the constructor gets called. It is almost as if I need to use a static constructor as described here: http://www.c-sharpcorner.com/uploadfile/cupadhyay/staticconstructors11092005061428am/staticconstructors.aspx except that my variables are not static. Java's static initializer comes to mind, but again - my variables are not static. http://www.glenmccl.com/tip_003.htm I want to make stylistic but not functional changes to this class. As crappy as it is, it has been tested and working for a few years now. breaking the functionality would be bad. So ... I am looking for shorter, sweeter, cuter, and yet EQUIVALENT code. Let me know if you have questions.

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• java annotations - problem with calling a locator class from a Vaadin Project

  - by George

  Hello, I'm not sure how to explain this without writing several pages so I hope the actual code is more expressive. I've made a jar containing multiple annotation declaration similar to the following: @Target(ElementType.PACKAGE) @Retention(RetentionPolicy.RUNTIME) public @interface MarkedPackage { } then I have made a test jar containing several classes in several packages and marked just one package with the above annotation (with package-info.java) like below: @myPackage.MarkedPackage package package.test.jar; this jar had in its build path the jar containing the annotations. then I made a static class that has a method (LoadPlugins) that retrieves a list with all the jars of a directory. Then it searches through the jars for the 'package-info' class and checks if that classes package contains the MarkedPackage annotation. by calling this: if (checkPackageAnnotation(thisClass.getPackage())) where thisClass is the package-info class retrieved via a classloader. and: public static boolean checkPackageAnnotation(AnnotatedElement elem) { System.out.println(elem.getAnnotations().length); if (elem == null || !elem.isAnnotationPresent(MarkedPackage.class)) return false; return true; } the elem.getAnnotatios().length is there for debug purposes. And the problem appears when I call the method from the static class: if I call it from a main function: public class MyMain { public static void main(String[] args){ PluginUtils.LoadPlugins(); } } everything works perfectly it displays '1' from that System.out.println(elem.getAnnotations().length); But if I call it from a button from my Vaadin project: header.addComponent(new Button("CallThat", new Button.ClickListener() { public void buttonClick(ClickEvent event) { PluginUtils.LoadPlugins(); } })); It displays '0' from that System.out.println(elem.getAnnotations().length); Also I should mention that I created the main inside my Vaadin project so it would have the exact same build path and resources. Is there a problem with web applications and that "@Retention(RetentionPolicy.RUNTIME)" ? hope I was clear enough... Hope someone has a solution for me... If you need more information - let me know. Thank you.

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• Dependency Properties, change notification and setting values in the constructor

  - by stefan.at.wpf

  Hello, I have a clas with 3 dependency properties A,B,C. The values of these properties are set by the constructor and every time one of the properties A, B or C changes, the method recalculate() is called. Now during execution of the constructor these method is called 3 times, because the 3 properties A, B, C are changed. Hoewever this isn't necessary as the method recalculate() can't do anything really useful without all 3 properties set. So what's the best way for property change notification but circumventing this change notification in the constructor? I thought about adding the property changed notification in the constructor, but then each object of the DPChangeSample class would always add more and more change notifications. Thanks for any hint! class DPChangeSample : DependencyObject { public static DependencyProperty AProperty = DependencyProperty.Register("A", typeof(int), typeof(DPChangeSample), new PropertyMetadata(propertyChanged)); public static DependencyProperty BProperty = DependencyProperty.Register("B", typeof(int), typeof(DPChangeSample), new PropertyMetadata(propertyChanged)); public static DependencyProperty CProperty = DependencyProperty.Register("C", typeof(int), typeof(DPChangeSample), new PropertyMetadata(propertyChanged)); private static void propertyChanged(DependencyObject d, DependencyPropertyChangedEventArgs e) { ((DPChangeSample)d).recalculate(); } private void recalculate() { // Using A, B, C do some cpu intensive caluclations } public DPChangeSample(int a, int b, int c) { SetValue(AProperty, a); SetValue(BProperty, b); SetValue(CProperty, c); } }

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• How are property assignment expressions handled in C#?

  - by Serious

  In C# you can use a property as both an lrvalue and rvalue at the same time like this : int n = N = 1; Here is a complete C# sample : class Test { static int n; static int N { get { System.Console.WriteLine("get"); return n; } set { System.Console.WriteLine("set"); n = value; } } static void Main() { int n = N = 1; System.Console.WriteLine("{0}/{1}", n, N); } } You can't do that in C++/CLI as the resulting type of the assignment expression "N = 1" is void. EDIT: here is a C++/CLI sample that shows this : ref class A { public: static property int N; }; int main() { int n = A::N = 1; System::Console::WriteLine("{0}/{1}", n, A::N); } So what's the magic behind C# syntax allowing a void-expression to be used as a rvalue ? Is this special treatment only available for properties or do you know other C# tricks like this ?

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• What is the right pattern for a async data fetching method in .net async/await

  - by s093294

  Given a class with a method GetData. A few other clients call GetData, and instead of it fetching data each time, i would like to create a pattern where the first call starts the task to get the data, and the rest of the calls wait for the task to complete. private Task<string> _data; private async Task<string> _getdata() { return "my random data from the net"; //get_data_from_net() } public string GetData() { if(_data==null) _data=_getdata(); _data.wait(); //are there not a problem here. cant wait a task that is already completed ? if(_data.status != rantocompletion) _data.wait() is not any better, it might complete between the check and the _data.wait? return _data.Result; } How would i do the pattern correctly? (Solution) private static object _servertime_lock = new object(); private static Task<string> _servertime; private static async Task<string> servertime() { try { var thetvdb = new HttpClient(); thetvdb.Timeout = TimeSpan.FromSeconds(5); // var st = await thetvdb.GetStreamAsync("http://www.thetvdb.com/api/Updates.php?type=none"); var response = await thetvdb.GetAsync("http://www.thetvdb.com/api/Updates.php?type=none"); response.EnsureSuccessStatusCode(); Stream stream = await response.Content.ReadAsStreamAsync(); XDocument xdoc = XDocument.Load(stream); return xdoc.Descendants("Time").First().Value; } catch { return null; } } public static async Task<string> GetServerTime() { lock (_servertime_lock) { if (_servertime == null) _servertime = servertime(); } var time = await _servertime; if (time == null) _servertime = null; return time; }

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• Fluent NHibernate Map to private/protected Field that has no exposing Property

  - by Jon Erickson

  I have the following Person and Gender classes (I don't really, but the example is simplified to get my point across), using NHibernate (Fluent NHibernate) I want to map the Database Column "GenderId" [INT] value to the protected int _genderId field in my Person class. How do I do this? FYI, the mappings and the domain objects are in separate assemblies. public class Person : Entity { protected int _genderId; public virtual int Id { get; private set; } public virtual string Name { get; private set; } public virtual Gender Gender { get { return Gender.FromId(_genderId); } } } public class Gender : EnumerationBase<Gender> { public static Gender Male = new Gender(1, "Male"); public static Gender Female = new Gender(2, "Female"); private static readonly Gender[] _genders = new[] { Male, Female }; private Gender(int id, string name) { Id = id; Name = name; } public int Id { get; private set; } public string Name { get; private set; } public static Gender FromId(int id) { return _genders.Where(x => x.Id == id).SingleOrDefault(); } }

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• Unable to step into interface implementation configured by unity application block

  - by Rahul

  I have configured a set of interface implementations with EntLib. unity block. The constructor of implementation classes work fine as soon as I run the application: 1. The interface to implement when I run the application the cctor runs fine, which shows that unity resolution was successful: But when I try to call a method of this class, the code just passes through without actually invoking the function of the implemented class: Edit: Added on June 11, 2012 Following is the Unity Configuration I have. (This is all the unity configuration I am doing) public class UnityControllerFactory : DefaultControllerFactory { private static readonly IUnityContainer container; private static UnityControllerFactory factory = null; static UnityControllerFactory() { container = new UnityContainer(); UnityConfigurationSection section = (UnityConfigurationSection)ConfigurationManager.GetSection("unity"); section.Configure(container); factory = new UnityControllerFactory(); } public static UnityControllerFactory GetControllerFactory() { return factory; } protected override IController GetControllerInstance(RequestContext requestContext, Type controllerType) { return container.Resolve(controllerType) as IController; } } I am unable to step into this code and the implementation simply skips out without executing anything. What is wrong here?

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• Modifying the initrd.img to run additional binaries in a PXE booted RHEL 6

  - by Charles Long

  I am trying to add additional automation to our existing RHEL 6 (or Oralce's implementation thereof) PXE install process by running a script in the %pre section of my kickstart config that call hpacucli, HP's raid device configuration binary. My approach has been to modify the PXE served initrd.img. I've unpacked the initrd.img and copied in the required libraries, binaries, and scripts but when the system boots using the modified initrd.img, the modified /lib (and /lib_64) are moved aside to /lib_old and /lib is linked to the /mnt/runtime/lib. How can I change this configuration so that the /lib is not moved (unlikely) or required libraries are available in the runtime /mnt/runtime/lib? To test and confirm this I've been able to get the install process to move to the 6th virtual console, which allows me to see errors, and then open a shell (a useful debugging mechanism). %pre exec /dev/tty6 2 /dev/tty6 chvt 6 /bin/sh

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• Why is my GUI unresponsive while a SwingWorker thread runs?

  - by Starchy

  Hello, I have a SwingWorker thread with an IOBound task which is totally locking up the interface while it runs. Swapping out the normal workload for a counter loop has the same result. The SwingWorker looks basically like this: public class BackupWorker extends SwingWorker<String, String> { private static String uname = null; private static String pass = null; private static String filename = null; static String status = null; BackupWorker (String uname, String pass, String filename) { this.uname = uname; this.pass = pass; this.filename = filename; } @Override protected String doInBackground() throws Exception { BackupObject bak = newBackupObject(uname,pass,filename); return "Done!"; } } The code that kicks it off lives in a class that extends JFrame: public void actionPerformed(ActionEvent event) { String cmd = event.getActionCommand(); if (BACKUP.equals(cmd)) { SwingUtilities.invokeLater(new Runnable() { public void run() { final StatusFrame statusFrame = new StatusFrame(); statusFrame.setVisible(true); SwingUtilities.invokeLater(new Runnable() { public void run () { statusFrame.beginBackup(uname,pass,filename); } }); } }); } } Here's the interesting part of StatusFrame: public void beginBackup(final String uname, final String pass, final String filename) { worker = new BackupWorker(uname, pass, filename); worker.execute(); try { System.out.println(worker.get()); } catch (InterruptedException e) { e.printStackTrace(); } catch (ExecutionException e) { e.printStackTrace(); } } } So far as I can see, everything "long-running" is handled by the worker, and everything that touches the GUI on the EDT. Have I tangled things up somewhere, or am I expecting too much of SwingWorker?

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• Independent name of a class

  - by tobi

  We have class lua. In lua class there is a method registerFunc() which is defined: void lua::registerFun() { lua_register( luaState, "asd", luaApi::asd); lua_register( luaState, "zxc", luaApi::zxc); } lua_register is a built-in function from lua library: http://pgl.yoyo.org/luai/i/lua_register it takes static methods from luaApi class as an 3rd argument. Now some programmer wants to use the lua class, so he is forced to create his own class with definitions of the static methods, like: class luaApi { public: static int asd(); static int zxc(); }; and now is the point. I don't want (as a programmer) to create class named exactly "luaApi", but e.g. myClassForLuaApi. But for now it's not possible because it is explicitly written in the code - in lua class: lua_register( luaState, "asd", luaApi::asd); I would have to change it to: lua_register( luaState, "asd", myClassForLuaApi::asd); but I don't want to (let's assume that the programmer has no access there). If it's still not understandable, I give up. :) Thanks.

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• Partially constructed object / Multi threading

  - by reto

  Heya! I'm using joda due to it's good reputation regarding multi threading. It goes great distances to make multi threaded date handling efficient, for example by making all Date/Time/DateTime objects immutable. But here's a situation where I'm not sure if Joda is really doing the right thing. It probably is correct, but I'd be very interested to see the explanation for it. When a toString() of a DateTime is being called Joda does the following: /* org.joda.time.base.AbstractInstant */ public String toString() { return ISODateTimeFormat.dateTime().print(this); } All formatters are thread safe, as they are as well ready-only. But what's about the formatter-factory: private static DateTimeFormatter dt; /* org.joda.time.format.ISODateTimeFormat */ public static DateTimeFormatter dateTime() { if (dt == null) { dt = new DateTimeFormatterBuilder() .append(date()) .append(tTime()) .toFormatter(); } return dt; } This is a common pattern in single threaded applications. I see the following dangers: Race condition during null check -- worst case: two objects get created. No Problem, as this is solely a helper object (unlike a normal singleton pattern situation), one gets saved in dt, the other is lost and will be garbage collected sooner or later. the static variable might point to a partially constructed object before the objec has been finished initialization (before calling me crazy, read about a similar situation in this Wikipedia article. So how does Joda ensure that not partially created formatter gets published in this static variable? Thanks for your explanations! Reto

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• JFrame that has multiple layers

  - by phunehehe

  Hello, I have a window that has two layers: a static background and a foreground that contains moving objects. My idea is to draw the background just once (because it's not going to change), so I make the changing panel transparent and add it on top of the static background. Here is the code for this: public static void main(String[] args) { JPanel changingPanel = new JPanel() { @Override public void paintComponent(Graphics g) { super.paintComponent(g); g.setColor(Color.RED); g.fillRect(100, 100, 100, 100); } }; changingPanel.setOpaque(false); JPanel staticPanel = new JPanel(); staticPanel.setBackground(Color.BLUE); staticPanel.setLayout(new BorderLayout()); staticPanel.add(changingPanel); JFrame frame = new JFrame(); frame.add(staticPanel); frame.setSize(800, 600); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); frame.setVisible(true); } This piece of code gives me the correct image I want, but every time I repaint changingPanel, staticPanel gets repainted as well (which is obviously against the whole idea of painting the static panel just once). Can somebody show me what's wrong? FYI I am using the javax.swing.Timer to recalculate and repaint the changing panel 24 times every second.

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• DataReader already open when using LINQ

  - by Jamie Dixon

  I've got a static class containing a static field which makes reference to a wrapper object of a DataContext. The DataContext is basically generated by Visual Studio when we created a dbml file & contains methods for each of the stored procedures we have in the DB. Our class basically has a bunch of static methods that fire off each of these stored proc methods & then returns an array based on a LINQ query. Example: public static TwoFieldBarData[] GetAgesReportData(string pct) { return DataContext .BreakdownOfUsersByAge(Constants.USER_MEDICAL_PROFILE_KEY, pct) .Select(x => new TwoFieldBarData(x.DisplayName, x.LeftValue, x.RightValue, x.TotalCount)) .ToArray(); } Every now and then, we get the following error: There is already an open DataReader associated with this Command which must be closed firs This is happening intermittently and I'm curious as to what is going on. My guess is that when there's some lag between one method executing and the next one firing, it's locking up the DataContext and throwing the error. Could this be a case for wrapping each of the DataContext LINQ calls in a lock(){} to obtain exclusivity to that type and ensure other requests are queued?

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• How to Inject code in c# method calls from a separate app

  - by Fusspawn

  I was curious if anyone knew of a way of monitoring a .Net application's runtime info (what method is being called and such) and injecting extra code to be run on certain methods from a separate running process. say i have two applications: app1.exe that for simplicity's sake could be class Program { static void Main(string[] args) { while(true){ Somefunc(); } } static void Somefunc() { Console.WriteLine("Hello World"); } } and I have a second application that I wish to be able to detect when Somefunc() from application 1 is running and inject its own code, class Program { static void Main(string[] args) { while(true){ if(App1.SomeFuncIsCalled) InjectCode(); } } static void InjectCode() { App1.Console.WriteLine("Hello World Injected"); } } So The result would be Application one would show Hello World Hello World Injected I understand its not going to be this simple ( By a long shot ) but I have no idea if it's even possible and if it is where to even start. Any suggestions ? I've seen similar done in java, But never in c#. EDIT: To clarify, the usage of this would be to add a plugin system to a .Net based game that I do not have access to the source code of.

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• Ninject: Shared DI/IoC container

  - by joblot

  Hi I want to share the container across various layers in my application. I started creating a static class which initialises the container and register types in the container. public class GeneralDIModule : NinjectModule { public override void Load() { Bind().To().InSingletonScope(); } } public abstract class IoC { private static IKernel _container; public static void Initialize() { _container = new StandardKernel(new GeneralDIModule(), new ViewModelDIModule()); } public static T Get<T>() { return _container.Get<T>(); } } I noticed there is a Resolve method as well. What is the difference between Resolve and Get? In my unit tests I don’t always want every registered type in my container. Is there a way of initializing an empty container and then register types I need. I’ll be mocking types as well in unit test so I’ll have to register them as well. There is an Inject method, but it says lifecycle of instance is not managed? Could someone please set me in right way? How can I register, unregister objects and reset the container. Thanks

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• What is a preferred method for automatically configuring and setting up an Ubuntu instance?

  - by sutch

  I am tired of manually configuring instances of Ubuntu for testing web applications and for setting up workstations. I'm even more frustrated by the issues caused by inconsistent configurations. Is there a method (hopefully not too time consuming to learn and setup) that allows for automation of the setup and configuration of an Ubuntu server or workstation from an ISO. This is primarily for virtual machine instances, but it would be helpful to also create instances on hardware. I am specifically looking for a method to automate the installation of libraries (apt-get), configure services (such as Apache and MySQL), add 3rd party software (download, extract and build), and add libraries to scripting languages (for example, Ruby Gems or CPAN packages for Perl).

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• how to generate unique numbers less than 8 characters long.

  - by loudiyimo

  hi I want to generate unique id's everytime i call methode generateCustumerId(). The generated id must be 8 characters long or less than 8 characters. This requirement is necessary because I need to store it in a data file and schema is determined to be 8 characters long for this id. Option 1 works fine. Instead of option 1, I want to use UUID. The problem is that UUID generates an id which has to many characters. Does someone know how to generate a unique id which is less then 99999999? option 1 import java.util.HashSet; import java.util.Random; import java.util.Set; public class CustomerIdGenerator { private static Set<String> customerIds = new HashSet<String>(); private static Random random = new Random(); // XXX: replace with java.util.UUID public static String generateCustumerId() { String customerId = null; while (customerId == null || customerIds.contains(customerId)) { customerId = String.valueOf(random.nextInt(89999999) + 10000000); } customerIds.add(customerId); return customerId; } } option2 generates an unique id which is too long public static String generateCustumerId() { String ownerId = UUID.randomUUID().toString(); System.out.println("ownerId " + ownerId); return ownerId }

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• The new operator in C# isn't overriding base class member

  - by Dominic Zukiewicz

  I am confused as to why the new operator isn't working as I expected it to. Note: All classes below are defined in the same namespace, and in the same file. This class allows you to prefix any content written to the console with some provided text. public class ConsoleWriter { private string prefix; public ConsoleWriter(string prefix) { this.prefix = prefix; } public void Write(string text) { Console.WriteLine(String.Concat(prefix,text)); } } Here is a base class: public class BaseClass { protected static ConsoleWriter consoleWriter = new ConsoleWriter(""); public static void Write(string text) { consoleWriter.Write(text); } } Here is an implemented class: public class NewClass : BaseClass { protected new static ConsoleWriter consoleWriter = new ConsoleWriter("> "); } Now here's the code to execute this: class Program { static void Main(string[] args) { BaseClass.Write("Hello World!"); NewClass.Write("Hello World!"); Console.Read(); } } So I would expect the output to be Hello World! > Hello World! But the output is Hello World Hello World I do not understand why this is happening. Here is my thought process as to what is happening: The CLR calls the BaseClass.Write() method The CLR initialises the BaseClass.consoleWriter member. The method is called and executed with the BaseClass.consoleWriter variable Then The CLR calls the NewClass.Write() The CLR initialises the NewClass.consoleWriter object. The CLR sees that the implementation lies in BaseClass, but the method is inherited through The CLR executes the method locally (in NewClass) using the NewClass.consoleWriter variable I thought this is how the inheritance structure works? Please can someone help me understand why this is not working?

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• C# iterator is executed twice when composing two IEnumerable methods

  - by achristoph

  I just started learning about C# iterator but got confused with the flow of the program after reading the output of the program. The foreach with uniqueVals seems to be executed twice. My understanding is that the first few lines up to the line before "Nums in Square: 3" should not be there. Can anyone help to explain why this happens? The output is: Unique: 1 Adding to uniqueVals: 1 Unique: 2 Adding to uniqueVals: 2 Unique: 2 Unique: 3 Adding to uniqueVals: 3 Nums in Square: 3 Unique: 1 Adding to uniqueVals: 1 Square: 1 Number returned from Unique: 1 Unique: 2 Adding to uniqueVals: 2 Square: 2 Number returned from Unique: 4 Unique: 2 Unique: 3 Adding to uniqueVals: 3 Square: 3 Number returned from Unique: 9 static class Program { public static IEnumerable<T> Unique<T>(IEnumerable<T> sequence) { Dictionary<T, T> uniqueVals = new Dictionary<T, T>(); foreach (T item in sequence) { Console.WriteLine("Unique: {0}", item); if (!uniqueVals.ContainsKey(item)) { Console.WriteLine("Adding to uniqueVals: {0}", item); uniqueVals.Add(item, item); yield return item; Console.WriteLine("After Unique yield: {0}", item); } } } public static IEnumerable<int> Square(IEnumerable<int> nums) { Console.WriteLine("Nums in Square: {0}", nums.Count()); foreach (int num in nums) { Console.WriteLine("Square: {0}", num); yield return num * num; Console.WriteLine("After Square yield: {0}", num); } } static void Main(string[] args) { var nums = new int[] { 1, 2, 2, 3 }; foreach (int num in Square(Unique(nums))) Console.WriteLine("Number returned from Unique: {0}", num); Console.Read(); } }

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• C++ data member initializer is not allowed

  - by user1435915

  I totally new to C++ so bear with me. I want to make a class with a static array, and access to this array from the main. Here is what i want to do in C#. namespace ConsoleApplication1 { class Program { static void Main(string[] args) { Class a = new Class(); Console.WriteLine(a.arr[1]); } } } ===================== namespace ConsoleApplication1 { class Class { public static string[] s_strHands = new string[]{"one","two","three"}; } } Here is what i have tried: // justfoolin.cpp : Defines the entry point for the console application. // #include "stdafx.h" #include <string> #include <iostream> using namespace std; class Class { public: static string arr[3] = {"one", "two", "three"}; }; int _tmain(int argc, _TCHAR* argv[]) { Class x; cout << x.arr[2] << endl; return 0; } But i got: IntelliSense: data member initializer is not allowed

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• Opening my application when a usb device is inserted on Windows using WMI

  - by rsteckly

  Hi, I'm trying to launch an event when someone plugs in a usb device. For now, I'm content to simply print something to the console (in the finished product, it will launch an application). This code is very loosely adapted from: http://serverfault.com/questions/115496/use-wmi-to-detect-a-usb-drive-was-connected-regardless-of-whether-it-was-mounted There's two problems: 1) I need to pass the argument to Management scope dynamically because this will be installed on computers I don't use or whose name I don't know. 2) I'm getting an invalid namespace exception when I call w.Start(); Any ideas what I'm doing wrong? static ManagementEventWatcher w=null; static void Main(string[] args) { AddInstUSBHandler(); for(;;); } public static void USBRemoved(object sneder, EventArgs e) { Console.WriteLine("A USB device inserted"); } static void AddInstUSBHandler() { WqlEventQuery q; ManagementScope scope = new ManagementScope("HQ\\DEV1"); scope.Options.EnablePrivileges=true; q=new WqlEventQuery(); q.EventClassName+="_InstanceCreationEvent"; q.WithinInterval=new TimeSpan(0,0,3); q.Condition=@"TargetInstance ISA 'Win32_USBControllerdevice'"; w=new ManagementEventWatcher(scope,q); w.EventArrived+=new EventArrivedEventHandler(USBRemoved); w.Start(); }

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• No Hibernate Exception on the same insert of data

  - by Mark Estrada

  Hi All, Hibernate Newbie here. I am quite unsure why I am not getting any exception when I am executing below code. On first attempt, this code creates the Book Entry on my Book Table. But my concern is that when I execute below code again, no error was pop out by Hibernate. I was in fact expecting some sort of Violation of Primary Key Constraints as what I have bee doing in JDBC code. public class BookDao { public void createBook(Book bookObj) { Session session = HibernateUtil.getSessionFactory() .getCurrentSession(); session.beginTransaction(); session.saveOrUpdate(bookObj); session.getTransaction().commit(); } } public class HibernateUtil { private static final SessionFactory sessionFactory = buildSessionFactory(); private static SessionFactory buildSessionFactory() { try { // Create the SessionFactory from hibernate.cfg.xml return new AnnotationConfiguration().configure() .buildSessionFactory(); } catch (Throwable ex) { // Make sure you log the exception, as it might be swallowed ex.printStackTrace(); throw new ExceptionInInitializerError(ex); } } public static SessionFactory getSessionFactory() { return sessionFactory; } } public class BookDBStarter { public static void main(String[] args) { Book bookHF = new Book(); bookHF.setIsbn("HF-12345"); bookHF.setName("Head First HTML"); bookHF.setPublishDate(new Date()); BookDao daoBook = new BookDao(); daoBook.createBook(bookHF); } } Is this normal hibernate way? And how will I know if my insert is successful? Any thoughts?

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• Declaration, allocation and assignment of an array of pointers to function pointers

  - by manneorama

  Hello Stack Overflow! This is my first post, so please be gentle. I've been playing around with C from time to time in the past. Now I've gotten to the point where I've started a real project (a 2D graphics engine using SDL, but that's irrelevant for the question), to be able to say that I have some real C experience. Yesterday, while working on the event system, I ran into a problem which I couldn't solve. There's this typedef, //the void parameter is really an SDL_Event*. //but that is irrelevant for this question. typedef void (*event_callback)(void); which specifies the signature of a function to be called on engine events. I want to be able to support multiple event_callbacks, so an array of these callbacks would be an idea, but do not want to limit the amount of callbacks, so I need some sort of dynamic allocation. This is where the problem arose. My first attempt went like this: //initial size of callback vector static const int initial_vecsize = 32; //our event callback vector static event_callback* vec = 0; //size static unsigned int vecsize = 0; void register_event_callback(event_callback func) { if (!vec) __engine_allocate_vec(vec); vec[vecsize++] = func; //error here! } static void __engine_allocate_vec(engine_callback* vec) { vec = (engine_callback*) malloc(sizeof(engine_callback*) * initial_vecsize); } First of all, I have omitted some error checking as well as the code that reallocates the callback vector when the number of callbacks exceed the vector size. However, when I run this code, the program crashes as described in the code. I'm guessing segmentation fault but I can't be sure since no output is given. I'm also guessing that the error comes from a somewhat flawed understanding on how to declare and allocate an array of pointers to function pointers. Please Stack Overflow, guide me.

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• How can a wix custom action dll call be made to use the debug runtime via a merge module?

  - by Benj

  I'm trying to create a debug build with a corresponding debug installer for our product. I'm new to Wix so please forgive any naivety contained herein. The debug Dlls in my project are dependent on both the VS2008 and the VS2008SP1 debug runtimes. I've created a merge module feature in wix to bundle those runtimes with my installer. <Include xmlns="http://schemas.microsoft.com/wix/2006/wi"> <!-- Include our 'variables' file --> <!--<?include variables.wxi ?>--> <!--<Fragment>--> <DirectoryRef Id="TARGETDIR"> <!-- Always install the 32 bit ATL/CRT libraries, but only install the 64 bit ones on a 64 bit build --> <Merge Id="AtlFiles_x86" SourceFile="$(env.CommonProgramFiles)\Merge Modules\Microsoft_VC90_ATL_x86.msm" DiskId="1" Language="1033"/> <Merge Id="AtlPolicy_x86" SourceFile="$(env.CommonProgramFiles)\Merge Modules\policy_9_0_Microsoft_VC90_ATL_x86.msm" DiskId="1" Language="1033"/> <Merge Id="CrtFiles_x86" SourceFile="$(env.CommonProgramFiles)\Merge Modules\Microsoft_VC90_DebugCRT_x86.msm" DiskId="1" Language="1033"/> <Merge Id="CrtPolicy_x86" SourceFile="$(env.CommonProgramFiles)\Merge Modules\policy_9_0_Microsoft_VC90_DebugCRT_x86.msm" DiskId="1" Language="1033"/> <Merge Id="MfcFiles_x86" SourceFile="$(env.CommonProgramFiles)\Merge Modules\Microsoft_VC90_DebugMFC_x86.msm" DiskId="1" Language="1033"/> <Merge Id="MfcPolicy_x86" SourceFile="$(env.CommonProgramFiles)\Merge Modules\policy_9_0_Microsoft_VC90_DebugMFC_x86.msm" DiskId="1" Language="1033"/> <!-- If this is a 64 bit build, install the relevant modules --> <?if $(env.Platform) = "x64" ?> <Merge Id="AtlFiles_x64" SourceFile="$(env.CommonProgramFiles)\Merge Modules\Microsoft_VC90_ATL_x86_x64.msm" DiskId="1" Language="1033"/> <Merge Id="AtlPolicy_x64" SourceFile="$(env.CommonProgramFiles)\Merge Modules\policy_9_0_Microsoft_VC90_ATL_x86_x64.msm" DiskId="1" Language="1033"/> <Merge Id="CrtFiles_x64" SourceFile="$(env.CommonProgramFiles)\Merge Modules\Microsoft_VC90_DebugCRT_x86_x64.msm" DiskId="1" Language="1033"/> <Merge Id="CrtPolicy_x64" SourceFile="$(env.CommonProgramFiles)\Merge Modules\policy_9_0_Microsoft_VC90_DebugCRT_x86_x64.msm" DiskId="1" Language="1033"/> <Merge Id="MfcFiles_x64" SourceFile="$(env.CommonProgramFiles)\Merge Modules\Microsoft_VC90_DebugMFC_x86_x64.msm" DiskId="1" Language="1033"/> <Merge Id="MfcPolicy_x64" SourceFile="$(env.CommonProgramFiles)\Merge Modules\policy_9_0_Microsoft_VC90_DebugMFC_x86_x64.msm" DiskId="1" Language="1033"/> <?endif?> </DirectoryRef> <Feature Id="MS2008_SP1_DbgRuntime" Title="VC2008 Debug Runtimes" AllowAdvertise="no" Display="hidden" Level="1"> <!-- 32 bit libraries --> <MergeRef Id="AtlFiles_x86"/> <MergeRef Id="AtlPolicy_x86"/> <MergeRef Id="CrtFiles_x86"/> <MergeRef Id="CrtPolicy_x86"/> <MergeRef Id="MfcFiles_x86"/> <MergeRef Id="MfcPolicy_x86"/> <!-- 64 bit libraries --> <?if $(env.Platform) = "x64" ?> <MergeRef Id="AtlFiles_x64"/> <MergeRef Id="AtlPolicy_x64"/> <MergeRef Id="CrtFiles_x64"/> <MergeRef Id="CrtPolicy_x64"/> <MergeRef Id="MfcFiles_x64"/> <MergeRef Id="MfcPolicy_x64"/> <?endif?> </Feature> <!--</Fragment>--> </Include> If I'm doing a debug build of the installer, I include that feature like so: <!-- The 'Feature' that contains the debug CRT/ATL libraries --> <?if $(var.Configuration) = "Debug"?> <?include ..\includes\MS2008_SP1_DbgRuntime.wxi?> <?endif?> The only problem is that my installer also includes a custom action which is also dependent on the debug runtime: <!-- Private key installer --> <Binary Id="InstallPrivateKey" SourceFile="..\InstallPrivateKey\win32\$(var.Configuration)\InstallPrivateKey.dll"></Binary> <CustomAction Id='InstallKey' BinaryKey='InstallPrivateKey' DllEntry='InstallPrivateKey'/> So how can I package the debug run time in such a way that the custom action also has access to it?

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