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  • SqlParameter contructor compiler overload choice

    - by Ash
    When creating a SqlParameter (.NET3.5) or OdbcParameter I often use the SqlParameter(string parameterName, Object value) constructor overload to set the value in one statement. When I tried passing a literal 0 as the value paramter I was initially caught by the C# compiler choosing the (string, OdbcType) overload instead of (string, Object). MSDN actually warns about this gotcha in the remarks section, but the explanation confuses me. Why does the C# compiler decide that a literal 0 parameter should be converted to OdbcType rather than Object? The warning also says to use Convert.ToInt32(0) to force the Object overload to be used. It confusingly says that this converts the 0 to an "Object type". But isn't 0 already an "Object type"? The Types of Literal Values section of this page seems to say literals are always typed and so inherit from System.Object. This behavior doesn't seem very intuitive given my current understanding? Is this something to do with Contra-variance or Co-variance maybe?

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  • Invoke an Overloaded Constructor through this keyword (What's the Different between this two Sample code?)

    - by Alireza Dehqani
    using System; namespace ConsoleApplication1 { class Program { static void Main() { // Sample Sample ob = new Sample(); // line1 // Output for line1 /* * Sample(int i) * Sample() / // Sample2 Sample2 ob2 = new Sample2(); // line2 // Output for line2 / * Sample2() */ } } class Sample { // Fields private int a; // Constructors public Sample(int i) // Main Constructor { Console.WriteLine(" Sample(int i)"); a = i; } // Default Constructor public Sample() : this(0) { Console.WriteLine(" Sample()"); } } class Sample2 { // fields private int a; // Constructors public Sample2(int i) { Console.WriteLine("Sample2(int i)"); a = i; } public Sample2() { Console.WriteLine("Sample2()"); a = 0; } } }

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  • In C#, can I hide/modify accessors in subclasses?

    - by Diego
    I'm not even sure what this principle is called or how to search for it, so I sincerely apologize if it has been brought up before, but the best way to do it is with an example. class Properties { public string Name { get; set; } } class MyClass { class SubProperties: Properties { public override Name { get { return GetActualName(); } set { _value = SetActualName(value); } } } public SubProperties ClassProperties; private GetActualName() { ClassProperties.Name = "name"; } private SetActualName(string s) { ClassProperties.Name = SomeOtherFunction(s); } } The idea is to have any object that instantiates MyClass have a fully accessible property ClassProperties. To that object, it would look exactly like a Properties object, but behind the scenes, MyClass is actually computing and modifying the results of the fields. This method of declaration is obviously wrong since I can't access GetActualName() and SetActualName() from within the SubProperties definition. How would I achieve something like this?

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  • [Ruby on Rails] scribd_fu gsub error

    - by siulamvictor
    I have an application which allow user upload documents to Scribd. I tried to use scribd_fu in Rails. An error occurred when the controller try to save the model. NoMethodError in DocumentsController#processupload private method `gsub' called for nil:NilClass here is the related controller def processupload @document = Document.new(params[:document]) if @document.save session[:scribdid] = @document.ipaper_access_key else xxxxx and this is the related html form <form action="/documents/processupload" enctype="multipart/form-data" method="post"> <input name="authenticity_token" type="hidden" value="FqTCmlGGIvRjiaiaa+YtF50wgI7FfpxfrZsulLCbXcw=" /> <label class="label_h2">Upload a Document</label> <input id="document_document_upload" name="document[document_upload]" size="30" type="file" /></div> <div class="buttons"><button type="submit" class="positive"><img src="/images/icons/tick.png" alt="Save Document"/>Save Document</button> </form> Is there anything wrong?

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  • Why should i use EJB?

    - by Nitesh Panchal
    Hello, As we all know that EJB's in 3.1 or 3.0 are simple POJOs. You just need to give annotations here and there and it gets converted to EJB from simple class. So, now my question is why should i use EJBs at all? Can i not do without them? In .Net i created class library and got things done. I never felt the need for anything like EJB. Simple classes were enough. Then, why in Java people stress on EJB? What is difference between a simple POJO and EJB in terms of execution and memory? Further which function should i write in EJB and which should i write in simple class? Should i dump every function in EJB only? or there is some kind of strategy? Does EJB provide anything special?

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  • Implements an Undo/Redo in MVC

    - by bnabilos
    Hello, I have a Java application and I want to implement an Undo/Redo option. the value that I want to stock and that I want to be able to recover is an integer. My Class Model implements the interface StateEditable and I have to redefine the 2 functions restoreState(Hashtable<?, ?> state) and storeState(Hashtable<Object, Object> state) but I don't know what to put on them. It will be really great if somebody can help me to do that. These are the first lines of my Model class, the value that I want to do an undo/redo on it is value public class Model extends Observable implements StateEditable { private int value = 5; private UndoManager undoRedo = new UndoManager(); final UndoableEditListener editListener = new UndoableEditListener() { public void undoableEditHappened(UndoableEditEvent evt) { undoRedo.addEdit(evt.getEdit()); } }; @Override public void restoreState(Hashtable<?, ?> state) { } @Override public void storeState(Hashtable<Object, Object> state) { } }

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  • How to convert an existing callback interface to use boost signals & slots

    - by the_mandrill
    I've currently got a class that can notify a number of other objects via callbacks: class Callback { virtual NodulesChanged() =0; virtual TurkiesTwisted() =0; }; class Notifier { std::vector<Callback*> m_Callbacks; void AddCallback(Callback* cb) {m_Callbacks.push(cb); } ... void ChangeNodules() { for (iterator it=m_Callbacks.begin(); it!=m_Callbacks.end(); it++) { (*it)->NodulesChanged(); } } }; I'm considering changing this to use boost's signals and slots as it would be beneficial to reduce the likelihood of dangling pointers when the callee gets deleted, among other things. However, as it stands boost's signals seems more oriented towards dealing with function objects. What would be the best way of adapting my code to still use the callback interface but use signals and slots to deal with the connection and notification aspects?

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  • Specifying distinct sequence per table in Hibernate on subclasses

    - by gutch
    Is there a way to specify distinct sequences for each table in Hibernate, if the ID is defined on a mapped superclass? All entities in our application extend a superclass called DataObject like this: @MappedSuperclass public abstract class DataObject implements Serializable { @Id @GeneratedValue(strategy = GenerationType.SEQUENCE) @Column(name = "id") private int id; } @Entity @Table(name = "entity_a") public class EntityA extends DataObject { ... } @Entity @Table(name = "entity_b") public class EntityB extends DataObject { ... } This causes all entities to use a shared sequence, the default hibernate_sequence. What I would like to do is use a separate sequence for each entity, for example entity_a_sequence and entity_b_sequence in the example above. If the ID were specified on the subclasses then I could use the @SequenceGenerator annotation to specify a sequence for each entity, but in this case the ID is on the superclass. Given that ID is in the superclass, is there a way I can use a separate sequence for each entity — and if so, how? (We are using PostgreSQL 8.3, in case that's relevant)

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  • Tool(s) to lower the friction of programming against Interfaces in Visual Studio C#?

    - by John
    Hi I am a relatively new user of Visual Studio and I am trying "program against interfaces". I can see that when I create a class I can "Extract Interface" from the Refactor menu but you seem to only get one shot at this. ie. If I add a read only property FullName to my Customer class I would like to be able to right click and update the interface. At the moment I can only create a new interface from the Refactor menu. I want to update the interface I have already created not create new one. So the kind of tool I would be looking for would display check boxes for all valid members of the class with those already in the interface checked. It would also be handy to be able to to create the initial interface file in a different project (in the same solution), and for the tool to keep track of this. Does such a tool / add in / menu item exist (other than Ctrl C / V)? Thanks, John

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  • Java How to call method of grand parents?

    - by Arkaha
    Let's assume I have 3 classes A, B and C, each one extending the previous one. How do I call the code in A.myMethod() from C.myMethod() if B also implements myMethod? class A { public void myMethod() { // some stuff for A } } class B extends A { public void myMethod() { // some stuff for B //and than calling A stuff super.myMethod(); } } class C extends B { public void myMethod() { // some stuff for C // i don't need stuff from b, but i need call stuff from A // something like: super.super.myMethod(); ?? how to call A.myMethod(); ?? } }

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  • Custom Classes Passed from Service to a UI threads via AIDL

    - by Honza Pokorny
    I have a service that regularly queries a web server for new messages. The service stores the new messages in an arrayList. These messages are implemented using a custom class, storing all kinds of metadata (strings and longs). An activity then connects to this service to retrieve those messages and display them to the user. I have an .aidl file that describes the interface that the service exposes. package com.example.package; interface MyInterface { List<Message> getMessages(); } The Message class extends the Parcelable class which should allow for the IPC transfer. The problem is this: Eclipse gives me an error saying that the type of List<Message> is unknown. Any imports are marked as invalid. Ideas? Thanks

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  • Multiple key/value pairs in HTTP POST where key is the same name

    - by randombits
    I'm working on an API that accepts data from remote clients, some of which where the key in an HTTP POST almost functions as an array. In english what this means is say I have a resource on my server called "class". A class in this sense, is the type a student sits in and a teacher educates in. When the user submits an HTTP POST to create a new class for their application, a lot of the key value pairs look like: student_name: Bob Smith student_name: Jane Smith student_name: Chris Smith What's the best way to handle this on both the client side (let's say the client is cURL or ActiveResource, whatever..) and what's a decent way of handling this on the server-side if my server is a Ruby on Rails app? Need a way to allow for multiple keys with the same name and without any namespace clashing or loss of data.

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  • How to override the behavior of Spring @Autowired

    - by Mark
    Hi a little background: I am Using Spring 2.5, and specifically spring IOC and annotations. I am using @Autowired in my code (the Autowiring is done by type) and use @Component for exposing Classes to the Automatic wiring. The situation described bellow arose while i tried to test my code. now to the problem: Note: i use a different Spring Context for the Test environment. I have a class FOO which is @Autowired but in the test context i want to use a different class of the same type MockFoo (extends FOO) The Spring Setup of course fails do so automatically due to multiple options for the Dependency Injection of the FOO class (both FOO and MockFOO comply to the Type check) I am looking for a way to inject the test bean instead of the original bean. I expected Spring to allow using the Context configurion file to override a bean injection or to order Spring not to autowire a specific bean BUT All these option seem to exists only for the beans which were originally defined in the Spring Context Configuration file

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  • How to import org.codehaus.groovy.scriptom.* on Groovy?

    - by Mulone
    Hi guys, I'm trying to run a Groovy app to manipulate Excel files on STS (by SpringSource) 2.3.0. My Groovy version is 1.7. Class: package com.mytool import org.codehaus.groovy.scriptom.ActiveXObject /** * @author Mulone * */ class SurveyTool { static main(args) { print 'test' def wshell = new ActiveXObject('Wscript.Shell') wshell.popup("Scriptom is Groovy") } } Sadly, this is what I get: org.codehaus.groovy.control.MultipleCompilationErrorsException: startup failed: C:\workspace\SurveyTool\src\com\geoadapta\surveytool\SurveyTool.groovy: 6: unable to resolve class org.codehaus.groovy.scriptom.ActiveXObject @ line 6, column 1. import org.codehaus.groovy.scriptom.ActiveXObject ^ 1 error I also tried to rename ActiveXObject to ActiveXProxy with the same result. I tried to import scriptom manually from the package scriptom-all-assembly-1.6.0 but I didn't work. Any idea? Cheers

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  • WebLogic Server internal server error

    - by Abhinav Pandey
    when I deploy a project in Apache Tomcat 6.0 it's working fine. When I deploy the same project in weblogic server 10.3 it's showing an error like below: Error 500--Internal Server Error javax.servlet.ServletException: [HTTP:101249][weblogic.servlet.internal.WebAppServletContext@ae43b8 - appName: '_appsdir_ab_dir', name: 'ab', context-path: '/ab', spec-version: 'null']: Servlet class FirstServlet for servlet FirstServlet could not be loaded because the requested class was not found in the classpath . java.lang.UnsupportedClassVersionError: FirstServlet : Unsupported major.minor version 51.0.

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  • Equivalent of public static final fields in Scala

    - by JT
    I'm learning Scala, and I can't figure out how to best express this simple Java class in Scala: public class Color { public static final Color BLACK = new Color(0, 0, 0); public static final Color WHITE = new Color(255, 255, 255); public static final Color GREEN = new Color(0, 0, 255); private static final int red; private static final int blue; private static final int green; public Color(int red, int blue, int green) { this.red = red; this.blue = blue; this.green = green; } // getters, et cetera } The best I have is the following: class Color(val red: Int, val blue: Int, val green: Int) object BLACK extends Color(0, 0, 0) object WHITE extends Color(255, 255, 255) object GREEN extends Color(0, 0, 255) But I lose the advantages of having BLACK, WHITE, and GREEN being tied to the Color namespace.

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  • Use the [Serializable] attribute or subclassing from MarshalByRefObject?

    - by Theo Lenndorff
    I'd like to use an object across AppDomains. For this I can use the [Serializeable] attribute: [Serializable] class MyClass { public string GetSomeString() { return "someString" } } Or subclass from MarshalByRefObject: class MyClass: MarshalByRefObject { public string GetSomeString() { return "someString" } } In both cases I can use the class like this: AppDomain appDomain = AppDomain.CreateDomain("AppDomain"); MyClass myObject = (MyClass)appDomain.CreateInstanceAndUnwrap( typeof(MyClass).Assembly.FullName, typeof(MyClass).FullName); Console.WriteLine(myObject.GetSomeString()); Why do both approaches seem to have the same effect? What is the difference in both approaches? When should I favor the one approach over the other? EDIT: At the surface I know that there are differences between both mechanisms, but if someone jumped out of a bush and asked me the question I couldn't give him a proper answer. The questions are quite open questions. I hoped that someone can explain it better than I could do.

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  • Php - Looping For Different CSS

    - by bob
    MySQL $selectSize = "SELECT * FROM products"; $querySize = $db->select($selectSize); while ($product = $db->fetcharray($querySize)) { HTML <ul> <li>Product A</li> <li>Product B</li> <li class='right'>Product C</li> <li>Product D</li> <li>Product E</li> <li class='right'>Product F</li> </ul> Question While getting the product, I want the Product C and Product F or any product after 3 loops will have class='right' to the list style. Let me know Thanks

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  • XML Deserialization

    - by Nave
    I have the following xml file. <a> <b> <c>val1</c> <d>val2</d> </b> <b> <c>val3</c> <d>val4</d> </b> <a> I want to deserialize this into a class and I want to access them with the objects of the class created. I am using C#. I am able to deserialize and get the value into the object of class ‘a’ (the <a> tag). but how to access the value of <b> from this object?

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  • How to limit choice field options based on another choice field in django admin

    - by umnik700
    I have the following models: class Category(models.Model): name = models.CharField(max_length=40) class Item(models.Model): name = models.CharField(max_length=40) category = models.ForeignKey(Category) class Demo(models.Model): name = models.CharField(max_length=40) category = models.ForeignKey(Category) item = models.ForeignKey(Item) In the admin interface when creating a new Demo, after user picks category from the dropdown, I would like to limit the number of choices in the "items" drop-down. If user selects another category then the item choices should update accordingly. I would like to limit item choices right on the client, before it even hits the form validation on the server. This is for usability, because the list of items could be 1000+ being able to narrow it down by category would help to make it more manageable. Is there a "django-way" of doing it or is custom JavaScript the only option here?

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  • How to call angular javascript directive methods from the global scope

    - by user1659278
    I have a directive like the one of the examples from AngularJS, shown below. How can I call the toggle method from the global scope? I want to be able to toggle the zippy from some legacy code. myApp.directive('zippy', function(){ return { restrict: 'E', replace: true, transclude: true, scope: { title:'bind' }, template: '<div class="zippy">' + '<div class="title">{{title}}</div>' + '<div class="body" ng-transclude></div>' + '</div>', link: function(scope, element, attrs) { var title = angular.element(element.children()[0]), opened = true; title.bind('click', toggle); function toggle() { opened = !opened; element.removeClass(opened ? 'closed' : 'opened'); element.addClass(opened ? 'opened' : 'closed'); } toggle(); } } });

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  • how can I implement Comparable more than once?

    - by codeman73
    I'm upgrading some code to Java 5 and am clearly not understanding something with Generics. I have other classes which implement Comparable once, which I've been able to implement. But now I've got a class which, due to inheritance, ends up trying to implement Comparable for 2 types. Here's my situation: I've got the following classes/interfaces: interface Foo extends Comparable<Foo> interface Bar extends Comparable<Bar> abstract class BarDescription implements Bar class FooBar extends BarDescription implements Foo With this, I get the error 'interface Comparable cannot be implemented more than once with different arguments...' Why can't I have a compareTo(Foo foo) implemented in FooBar, and also a compareTo(Bar) implemented in BarDescription? Isn't this simply method overloading?

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  • Code editor with autocomplete

    - by Andrey
    I need to create a code editor for my own simple language: className.MethodName(parameterName = 2, ... ) I've created the appropriate grammar and autogenerate parser using ANTLR tool. Now I would like to have an autocomplete for class, method, variables and parameter names. This list should be context dependent, f.e. for "class." it should display methods and for "class.Method(" - parameters. I was going to parse the text and display the list depending on in which node the cursor is. The problem is that for incomplete code like "aaa.bbb(" the parser produces an error instead of a syntax tree. Any idea how to solve this problem? Maybe I'm on the wrong way and I shouldn't parse code to display autocomplete?

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  • How do I improve the efficiency of the queries executed by this generic Linq-to-SQL data access clas

    - by Lee D
    Hi all, I have a class which provides generic access to LINQ to SQL entities, for example: class LinqProvider<T> //where T is a L2S entity class { DataContext context; public virtual IEnumerable<T> GetAll() { return context.GetTable<T>(); } public virtual T Single(Func<T, bool> condition) { return context.GetTable<T>().SingleOrDefault(condition); } } From the front end, both of these methods appear to work as you would expect. However, when I run a trace in SQL profiler, the Single method is executing what amounts to a SELECT * FROM [Table], and then returning the single entity that meets the given condition. Obviously this is inefficient, and is being caused by GetTable() returning all rows. My question is, how do I get the query executed by the Single() method to take the form SELECT * FROM [Table] WHERE [condition], rather than selecting all rows then filtering out all but one? Is it possible in this context? Any help appreciated, Lee

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  • how to register a selectionProvider for the Viewer from a superclass

    - by Tom
    I have a View which extends a View provided by another plugin like this; public class View2 extends some.other.package.View1 { public void createPartControl(Composite parent) { super.createPartControl(parent); //I want to do this, but I can't because its private //getSite().setSelectionProvider(treeViewer); } } But I can't edit the super class, so I need to access the viewer from the Control. public class some.other.package.View1 extends ViewPart { private TreeViewer treeViewer; public void createPartControl(Composite parent) { treeViewer = new TreeViewer(parent, SWT.V_SCROLL); } } I tried using parent.getChildren(); to get a Tree object, but I can't see that it can be cooerced into an ISElectionProvider as required

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