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  • How to implement Voting for Grails Domain Classes?

    - by userWebMobile
    I have a Book class and need to implement a yes/no voting functionality. My domain classes look like this: class Book { String title static hasMany = [votes: Vote] } class User { String name static hasMany = [votes: Vote] } class Vote { boolean yesVote static belongsTo = [user: User, book: Book] } What is the best way to implement a voting for the book class. I need the following informations: What is the average yesVote for a book over all votes (either yes or no)? How to check if a specific user has done a vote? What is the best way to implement the computation of the average yesVote such that the performance does not drop?

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  • Why do Java source files go into a directory structure?

    - by bdhar
    Suppose that I am creating a Java project with the following classes com.bharani.ClassOne com.bharani.ClassTwo com.bharani.helper.HelperOne com.bharani.helper.support.HelperTwo with files put immediately under the folder 'src' src/ClassOne.java src/ClassTwo.java src/HelperOne.java src/HelperTwo.java and compile them using the command $ javac src/*.java -d classes (assuming that classes directory exists) The compiler compiles these files and put the class files in appropriate sub-directories inside the 'classes' directory like this classes/com/bharani/ClassOne.class classes/com/bharani/ClassTwo.class classes/com/bharani/helper/HelperOne.class classes/com/bharani/helper/support/HelperTwo.class Because the spec mandates that the classes should go inside appropriate directory structure. Fine. My question is this: When I use an IDE such as Eclipse or NetBeans, they create the directory structure for the source code directory ('src' directory here) also. Why is that? Is it mandatory? Or, is it just a convention? Thanks.

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  • Managing Data Dependecies of Java Classes that Load Data from the Classpath at Runtime

    - by Martin Potthast
    What is the simplest way to manage dependencies of Java classes to data files present in the classpath? More specifically: How should data dependencies be annotated? Perhaps using Java annotations (e.g., @Data)? Or rather some build entries in a build script or a properties file? Is there build tool that integrates and evaluates such information (Ant, Scons, ...)? Do you have examples? Consider the following scenario: A few lines of Ant create a Jar from my sources that includes everything found on the classpath. Then jarjar is used to remove all .class files that are not necessary to execute, say, class Foo. The problem is that all the data files that class Bar depends upon are still there in the Jar. The ideal deployment script, however, would recognize that the data files on which only class Bar depends can be removed while data files on which class Foo depends must be retained. Any hints?

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  • Which is Better: Revo Uninstaller or a Free Alternative?

    - by The Geek
    The results might surprise you! Our friends over at 7 Tutorials did some testing and found that the free IObit uninstaller application actually stacked up pretty well against the paid solution from Revo—though perhaps with a few less features. Note: we’ve always been fans of Revo Uninstaller around here, since it does have a lot of features to help clean up bad apps that the free alternatives don’t have. Either way, the 7 Tutorials article is worth a read. Roundup of Software Uninstallers – Reviewing IObit vs Ashampoo vs Revo [7 Tutorials] Use Amazon’s Barcode Scanner to Easily Buy Anything from Your Phone How To Migrate Windows 7 to a Solid State Drive Follow How-To Geek on Google+

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  • Missing feature in Hyper-V from Virtual PC

    - by Kevin Shyr
    One thing I really miss is the ability to create shared folder between host and guest.  Virtual PC does this well, you can create Shared Folder to be used every time, or just this one.  I have read some posts on how to do this.  Some people suggest using ISO Creator to package up the files and mount the image to DVD drive, but what I need is truly a "shared" environment, so I'm currently looking into creating Virtual switch and creating an internal network between the host and guest.  Let's see how that works out. I would have loved to give Virtual SAN Manager a try, but I don't have a local Fibre Channel to set one up. I guess this might be an extension to my original post:  http://geekswithblogs.net/LifeLongTechie/archive/2011/05/05/windows-virtual-pc-vs.-hyper-v-virtual-machines-vs.-windows-virtual.aspx

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  • C# Reflection and Getting Properties

    - by Nathan
    I have the following dummy class structure and I am trying to find out how to get the properties from each instance of the class People in PeopleList. I know how to get the properties from a single instance of People but can't for the life of me figure out how to get it from PeopleList. I am sure this is really straightforward but can someone point me in the right direction? public class Example { public class People { private string _name; public string Name { get { return _name; } set { _name = value; } } private int _age; public int Age { get { return _age; } set { _age = value; } } public People() { } public People(string name, int age) { this._name = name; this._age = age; } } public class PeopleList : List<People> { public static void DoStuff() { PeopleList newList = new PeopleList(); // Do some stuff newList.Add(new People("Tim", 35)); } } }

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  • C++ Forward declaration for virtual function

    - by Gokul
    Hi, I have a class hierarchy and i am writing a virtual function in it. Say there are three classes class A { virtual A* test(); }; ( File A.h ) class B : public A { virtual C* test(); }; ( File B.h ) class C : public A {}; ( File C.h ) Now is it possible for me to avoid including C.h in B.h, by doing some kind of forward declaration saying that C is a sub-class of A? Thanks, Gokul.

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  • preg_replace hell

    - by Jason
    I'm trying to use preg_replace to get some data from a remote page, but I'm having a bit of an issue when it comes to sorting out the pattern. function getData($Url){ $str = file_get_contents($Url); if(strlen($str)>0){ preg_match("/\<span class=\"SectionHeader\"\>title\</span>/<br/>/\<div class=\"header2\"\>(.*)\</div\></span\>/",$str,$title); return $title[1]; } } Here's the HTML as is before I ended up throwing a million slashes at it (looks like I forgot a part or two): <span class="cell CellFullWidth"><span class="SectionHeader">mytitle</span><br/><div class="Center">Event Name</div></span> Where Event Name is the data I want to return in my function. Thanks a lot guys, this is a pain in the ass.

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  • Data architecture for event log metrics?

    - by elliot42
    My service has a large ongoing number of user events, and we would like to do things like "count occurrence of event type T since date D." We are trying to make two basic decisions: What to store? Storing every event vs. only storing aggregates (Event log style) log every event and count them later, vs. (Time-series style) store a single aggregated "count of event E for date D" for every day Where to store the data In a relational database (particularly MySQL) In a non-relational (NoSQL) database In flat log files (collected centrally over the network via syslog-ng) What is standard practice / where can I read more about comparing the different types of systems? Additional details: The total event stream is large, potentially hundreds of thousands of entries per day But our current need is only to count certain types of events within it We don't necessarily need real-time access to the raw data or aggregation results IMHO, "log all events to files, crawl them at a later time to filter and aggregate the stream" is a pretty standard UNIX Way, but my Rails-y compatriots seem to think that nothing is real unless it's in MySQL.

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  • "Personal" method in ruby

    - by steve gooberman-hill
    I'm looking for a way of making a method "personal" - note NOT PRIVATE to a class here is an example - by "personal" I mean the behaviour of method "foo" class A def foo "foo" end end class B < A def foo "bar" end end class C < B end a=A.new; b=B.new;c=C.new I'm looking for a way of producing the following behaviour a.foo #=> "foo" b.foo #=> "bar" c.foo #=> "foo" (ultimate base class method called) Any ideas? Thanks Steve

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  • Should I create protected constructor for my singleton classes?

    - by Vijay Shanker
    By design, in Singleton pattern the constructor should be marked private and provide a creational method retuning the private static member of the same type instance. I have created my singleton classes like this only. public class SingletonPattern {// singleton class private static SingletonPattern pattern = new SingletonPattern(); private SingletonPattern() { } public static SingletonPattern getInstance() { return pattern; } } Now, I have got to extend a singleton class to add new behaviors. But the private constructor is not letting be define the child class. I was thinking to change the default constructor to protected constructor for the singleton base class. What can be problems, if I define my constructors to be protected? Looking for expert views....

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  • A c# Generics question involving Controllers and Repositories

    - by UpTheCreek
    I have a base repository class which contains all the common repository methods (as generic): public abstract class BaseRepository<T, IdType> : IBaseRepository<T, IdType> My repositories from this base e.g.: public class UserRepository : BaseRepository<User, int>, IUserRepository I also have a base controller class containing common actions, and inherit from this in controllers. The repository is injected into this by DI. E.g. public class UserController : BaseController<User> { private readonly IUserRepository userRepository; public UserController (IUserRepository userRepository) { this.userRepository= userRepository; } My question is this: The base controller needs to be able to access the repository methods that are defined in the base repository. However I'm passing in via DI a different repository type for each controller (even though they all inherrit from the base repository). How can the base controller somehow access the repository that is passed in (regardless of what type it is), so that it can access the common base methods?

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  • Using enums or a set of classes when I know I have a finite set of different options?

    - by devoured elysium
    Let's say I have defined the following class: public abstract class Event { public DateTime Time { get; protected set; } protected Event(DateTime time) { Time = time; } } What would you prefer between this: public class AsleepEvent : Event { public AsleepEvent(DateTime time) : base(time) { } } public class AwakeEvent : Event { public AwakeEvent(DateTime time) : base(time) { } } and this: public enum StateEventType { NowAwake, NowAsleep } public class StateEvent : Event { protected StateEventType stateType; public MealEvent(DateTime time, StateEventType stateType) : base(time) { stateType = stateType; } } and why? I am generally more inclined to the first option, but I can't explain why. Is it totally the same or are any advantages in using one instead of the other? Maybe with the first method its easier to add more "states", altough in this case I am 100% sure I will only want two states: now awake, and now asleep (they signal the moments when one awakes and one falls asleep).

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  • C# 4.0 dynamics

    - by mehanik
    Hi. Code bellow is working well until I have class ClassSameAssembly in same assembly as class Program. But when I move class ClassSameAssembly to separate assembly I have runtime error. Is it posible to resolve it? using System; namespace ConsoleApplication2 { public static class ClassSameAssembly { public static dynamic GetValues() { return new { Name = "Michael", Age = 20 }; } } internal class Program { private static void Main(string[] args) { var d = ClassSameAssembly.GetValues(); Console.WriteLine("{0} is {1} years old", d.Name, d.Age); } } }

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  • What is the most serious limitation of Unity?

    - by ashes999
    Having read this heated question about Unity vs. UDK vs. ID something, I'm curious to know: what the repeatedly-hit, most crippling limitation(s) of Unity? In order to keep this question non-subjective, again, I'm talking about the top repeated offender(s) of Unity are. This is something that, as a Unity user, you really wish someone had told you about before you started using it. I have heard from someone that Unity does not deal well with version control, since it generates a lot of binary files (which are un-diffable). This, to me, is not really crippling as I work alone. Thoughts?

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  • Java cannot find symbol enum

    - by JDelage
    Hi, I'm modeling a chess game on Java, and I'm having some problem. Here's what the code looks like (the relevant parts): Enum class Couleur.java: public enum Couleur {BLANC, NOIR} Piece.java: public abstract class Piece { (...) public Piece(Couleur couleurParam){ this.couleurPiece = couleurParam; } (...) } And finally Tour.java: public class Tour extends Piece { (...) public Tour(Couleur couleurParam){ super(couleurParam); } (...) } All the .java files are in the same folder. Yet at compile I get a "cannot find symbol symbol : variable NOIR location: class Plateau" (Plateau is the class that instantiates Tour.) Can anyone help me figure out what's wrong here? Many thanks, JDelage

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  • Avoid warning 'Unreferenced Formal Parameter'

    - by bdhar
    I have a super class like this: class Parent { public: virtual void Function(int param); }; void Parent::Function(int param) { std::cout << param << std::endl; } ..and a sub-class like this: class Child : public Parent { public: void Function(int param); }; void Child::Function(int param) { ;//Do nothing } When I compile the sub-class .cpp file, I get this error warning C4100: 'param' : unreferenced formal parameter As a practise, we used to treat warnings as errors. How to avoid the above warning? Thanks.

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  • Is it possible to create nested classes in PHP as it is in C#?

    - by Edward Tanguay
    In C# you can have nested classes like this, which are useful if you have classes which do not have meaning outside the scope of one particular class, e.g. in a factory pattern: public abstract class BankAccount { private BankAccount() {} private sealed class SavingsAccount : BankAccount { ... } private sealed class CheckingAccount : BankAccount { ... } public BankAccount MakeSavingAccount() { ... } public BankAccount MakeCheckingAccount() { ... } } Is this possible in PHP? I've read that it was planned for PHP 5, then cancelled, then planned again, but can't find definitive info. Does anyone know how to create nested classes (classes within the scope of another class) as in the above C# example using PHP 5.3?

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  • NSInvocation: object does not implement methodSignatureForSelector

    - by Sam V
    I have this weird crash that only happens when running the app on the device (doesn't happen in the Simulator). It seems like the problem surfaces out of nowhere, as I haven't changed anything on that particular class. I had the very same issue a few days ago, and I ended up fixing it by duplicating the class, renaming it, and changing the referenced class — I haven't changed a single bit of code. So I'm trying to understand why it's doing this. I've read somewhere that usually you get this console error when the object isn't a subclass of NSObject (but it is!). Here's the exact console error message: *** NSInvocation: warning: object 0x679e0 of class 'FFProximityPickerView' does not implement methodSignatureForSelector: -- trouble ahead *** NSInvocation: warning: object 0x679e0 of class 'FFProximityPickerView' does not implement doesNotRecognizeSelector: -- abort And then it crashes. I'd be very thankful for anyone who can help me on this.

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  • How to discover table properties from SQLAlchemy mapped object

    - by ssaboum
    Hi, My point is i have a class mapped with a table, in my case in a declarative way, and i want to "discover" table properties, columns, names, relations, from this class : engine = create_engine('sqlite:///' + databasePath, echo=True) # setting up root class for declarative declaration Base = declarative_base(bind=engine) class Ship(Base): __tablename__ = 'ships' id = Column(Integer, primary_key=True) name = Column(String(255)) def __init__(self, name): self.name = name def __repr__(self): return "<Ship('%s')>" % (self.name) So now my goal is from the "Ship" class to get the table columns and their properties from another piece of code. I guess i can deal with it using instrumentation but is there any way provided by the SQLAlchemy API ? Thank you.

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  • Targeting .Net framework version 3.0. (4 replies)

    I have developed a VB.NET application and am trying to target .net framework V3.0. The project was initially developed using Visual Studio 2005. I am now using VS 2008 Professional. I go to project\properties\compile\advanced compile options. From the &quot;Target Framework&quot; dropdown list box, I select .NET Framework 3.0. VS informs me that it needs to close and re open the project. Fine. Once the proj...

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  • Reflection: take values from an unknown running alpplication

    - by Dr.Lesh
    I'm writing an application that searchs for Semaphore types in the fields of unknown classes in unknown application (passed by user). I made it using Reflection and it worked. Now I want to fill up these semaphores with values, taking them from a running instance of this unknown application. So i took the class with "main" method of this unknown application, made a newInstance, and passed it when invoking the main method to start the application: Class mainClass = getItSomeWhere(); Object instance = mainClass.newInstance(); Method mainMethod = mainClass.getDeclaredMethod("main", new Class[]{String[].class}); mainMethod.invoke(instance, new Object[]{args}); and it worked fine. Now, how can I get the semaphore values, taking them from the classes of this running application, when I only have an instance of the main class? Many thanks for the answers.

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  • What really is the purpose of "base" keyword in c#?

    - by Pandiya Chendur
    Thus for used base class for some commom reusable methods in every page of my application... public class BaseClass:System.Web.UI.Page { public string GetRandomPasswordUsingGUID(int length) { string guidResult = System.Guid.NewGuid().ToString(); guidResult = guidResult.Replace("-", string.Empty); return guidResult.Substring(0, length); } } So if i want to use this method i would just do, public partial class forms_age_group : BaseClass { protected void Page_Load(object sender, EventArgs e) { //i would just call it like this string pass = GetRandomPasswordUsingGUID(10); } } It does what i want but there is a "Base" keyword that deals with base class in c# ... I really want to know when should use base keyword in my derived class.... Any good example...

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  • How can I create a generic constructor? (ie. BaseClass.FromXml(<param>)

    - by SofaKng
    I'm not sure how to describe this but I'm trying to create a base class that contains a shared (factory) function called FromXml. I want this function to instantiate an object of the proper type and then fill it via an XmlDocument. For example, let's say I have something like this: Public Class XmlObject Public Shared Function FromXml(ByVal source as XmlDocument) As XmlObject // <need code to create SPECIFIC TYPE of object and return it End Function End Class Public Class CustomObject Inherits XmlObject End Class I'd like to be able to do something like this: Dim myObject As CustomObject = CustomObject.FromXml(source) Is this possible?

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  • ComboBox Data Binding

    - by Geertjan
    Let's create a databound combobox, levering MVC in a desktop application. The result will be a combobox, provided by the NetBeans ChoiceView, that displays data retrieved from a database: What follows is not much different from the NetBeans Platform CRUD Application Tutorial and you're advised to consult that document if anything that follows isn't clear enough. One kind of interesting thing about the instructions that follow is that it shows that you're able to create an application where each element of the MVC architecture can be located within a separate module: Start by creating a new NetBeans Platform application named "MyApplication". Model We're going to start by generating JPA entity classes from a database connection. In the New Project wizard, choose "Java Class Library". Click Next. Name the Java Class Library "MyEntities". Click Finish. Right-click the MyEntities project, choose New, and then select "Entity Classes from Database". Work through the wizard, selecting the tables of interest from your database, and naming the package "entities". Click Finish. Now a JPA entity is created for each of the selected tables. In the Project Properties dialog of the project, choose "Copy Dependent Libraries" in the Packaging panel. Build the project. In your project's "dist" folder (visible in the Files window), you'll now see a JAR, together with a "lib" folder that contains the JARs you'll need. In your NetBeans Platform application, create a module named "MyModel", with code name base "org.my.model". Right-click the project, choose Properties, and in the "Libraries" panel, click Add Dependency button in the Wrapped JARs subtab to add all the JARs from the previous step to the module. Also include "derby-client.jar" or the equivalent driver for your database connection to the module. Controler In your NetBeans Platform application, create a module named "MyControler", with code name base "org.my.controler". Right-click the module's Libraries node, in the Projects window, and add a dependency on "Explorer & Property Sheet API". In the MyControler module, create a class with this content: package org.my.controler; import org.openide.explorer.ExplorerManager; public class MyUtils { static ExplorerManager controler; public static ExplorerManager getControler() { if (controler == null) { controler = new ExplorerManager(); } return controler; } } View In your NetBeans Platform application, create a module named "MyView", with code name base "org.my.view".  Create a new Window Component, in "explorer" view, for example, let it open on startup, with class name prefix "MyView". Add dependencies on the Nodes API and on the Explorer & Property Sheet API. Also add dependencies on the "MyModel" module and the "MyControler" module. Before doing so, in the "MyModel" module, make the "entities" package and the "javax.persistence" packages public (in the Libraries panel of the Project Properties dialog) and make the one package that you have in the "MyControler" package public too. Define the top part of the MyViewTopComponent as follows: public final class MyViewTopComponent extends TopComponent implements ExplorerManager.Provider { ExplorerManager controler = MyUtils.getControler(); public MyViewTopComponent() { initComponents(); setName(Bundle.CTL_MyViewTopComponent()); setToolTipText(Bundle.HINT_MyViewTopComponent()); setLayout(new BoxLayout(this, BoxLayout.PAGE_AXIS)); controler.setRootContext(new AbstractNode(Children.create(new ChildFactory<Customer>() { @Override protected boolean createKeys(List list) { EntityManager entityManager = Persistence. createEntityManagerFactory("MyEntitiesPU").createEntityManager(); Query query = entityManager.createNamedQuery("Customer.findAll"); list.addAll(query.getResultList()); return true; } @Override protected Node createNodeForKey(Customer key) { Node customerNode = new AbstractNode(Children.LEAF, Lookups.singleton(key)); customerNode.setDisplayName(key.getName()); return customerNode; } }, true))); controler.addPropertyChangeListener(new PropertyChangeListener() { @Override public void propertyChange(PropertyChangeEvent evt) { Customer selectedCustomer = controler.getSelectedNodes()[0].getLookup().lookup(Customer.class); StatusDisplayer.getDefault().setStatusText(selectedCustomer.getName()); } }); JPanel row1 = new JPanel(new FlowLayout(FlowLayout.LEADING)); row1.add(new JLabel("Customers: ")); row1.add(new ChoiceView()); add(row1); } @Override public ExplorerManager getExplorerManager() { return controler; } ... ... ... Now run the application and you'll see the same as the image with which this blog entry started.

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