Search Results

Search found 577 results on 24 pages for 'delegates'.

Page 19/24 | < Previous Page | 15 16 17 18 19 20 21 22 23 24  | Next Page >

• What can cause Windows to unhook a low level (global) keyboard hook?

  - by Davy8

  We have some global keyboard hooks installed via SetWindowsHookEx with WH_KEYBOARD_LL that appear to randomly get unhooked by Windows. We verified that they hook was no longer attached because calling UnhookWindowsHookEx on the handle returns false. (Also verified that it returns true when it was working properly) There doesn't seem to be a consistent repro, I've heard that they can get unhooked due to timeouts or exceptions getting thrown, but I've tried both just letting it sit on a breakpoint in the handling method for over a minute, as well as just throwing a random exception (C#) and it still appears to work. In our callback we quickly post to another thread, so that probably isn't the issue. I've read about solutions in Windows 7 for setting the timeout higher in the registry because Windows 7 is more aggressive about the timeouts apparently (we're all running Win7 here, so not sure if this occurs on other OS's) , but that doesn't seem like an ideal solution. I've considered just having a background thread running to refresh the hook every once in a while, which is hackish, but I don't know of any real negative consequences of doing that, and it seems better than changing a global Windows registry setting. Any other suggestions or solutions? The delegates are not being GC'd since they're static members, which is one cause that I've read about.

  Read the article

• Accessing class member variables inside a BackgroundWorker's DoWork event handler, and other Backgro

  - by Justin

  Question 1 In the DoWork event handler of a BackgroundWorker, is it safe to access (for both reading and writing) member variables of the class that contains the BackgroundWorker? Is it safe to access other variables that are not declared inside the DoWork event handler itself? Obviously DoWork should not be accessing any UI objects of, say, a WinForms application, as the UI should only be updated from the UI thread. But what about accessing other (not UI-related) member variables? The reason why I ask is that I've seen the occasional comment come up while Googling saying that accessing member variables is not allowed. The only example I can find at the moment is a comment on this MSDN page, which says: Note, that the BGW can cause exceptions if it attempts to access or modify class level variables. All data must be passed to it by delegates and events. And also: NEVER. NEVER. Never try to reference variables not declared inside of DoWork. It may seem to work at times, but in reality you are just getting lucky. As far as I know, MSDN itself does not document any restrictions of this kind (although if I'm wrong, I'd appreciate a link). But comments like these do seem to pop up every now and again. (Of course if DoWork does access/modify a member variable that could be accessed/modified by the main thread at the same time, it is necessary to synchronise access to that field, eg by using a locking object. But the above quotes seem to require a blanket ban of accessing member variables, rather than just synchronising access!) Question 2 To make this into a more general question, are there any other (not documented?) restrictions that users of the BackgroundWorker should be aware of, aside from the above? Any "best practices", perhaps?

  Read the article

• Can't contravariance be solved with interfaces?

  - by Sir Psycho

  Hi, I'm at the point where I'm starting to grasp contravariance, although I'm trying to work out what the advantage is when an interface can be used instead. Obviously I'm missing something. Here is the c#4 example class Dog : Animal { public Dog(string name) : base(name) { } } class Animal { string _name; public Animal(string name) { _name = name; } public void Walk() { Console.WriteLine(_name + " is walking"); } } Action<Animal> MakeItMove = (ani) => { ani.Walk(); }; Action<Dog> MakeItWalk = MakeItMove; MakeItWalk(new Dog("Sandy")); Same example which works in earlier versions on c# class Dog : Animal { public Dog(string name) : base(name) { } } class Animal : IAnimal { string _name; public Animal(string name) { _name = name; } public void Walk() { Console.WriteLine(_name + " is walking"); } } interface IAnimal { void Walk(); } Action<IAnimal> MakeItMove = (ani) => { ani.Walk(); }; Action<IAnimal> MakeItWalk = MakeItMove; MakeItWalk(new Dog("Sandy")); These may not be the best examples, but I still can't seem to 'get it'. Is the in keywork defined on the action delegate simply a short hand syntax way like lamda is to delegates?

  Read the article

• Niewbie OutOfMemory problem

  - by Nick

  So I am trying to create a producer/consumer type scala app. The LoopControl just sends a message to the MessageReceiver continoually. The MessageReceiver then delegates work to the MessageCreatorActor (whose work is to check a map for an object, and if not found create one and start it up). Each MessageActor created by this MessageCreatorActor is associated with an Id. Eventually this is where I want to do business logic. But I run out of memory after 15 minutes. Any help is appreciated import scala.actors.Actor import java.util.HashMap; import scala.actors.Actor._ case object LoopControl case object MessageReceiver case object MessageActor case object MessageActorCreator class MessageReceiver(msg: String) extends Actor { var messageActorMap = new HashMap[String, MessageActor] val messageCreatorActor = new MessageActorCreator(null, null) def act() { messageCreatorActor.start loop { react { case MessageActor(messageId) = if (msg.length() 0) { var messageActor = messageActorMap.get(messageId); if(messageActor == null) { messageCreatorActor ! MessageActorCreator(messageId, messageActorMap) }else { messageActor ! MessageActor } } } } } } case class MessageActorCreator(msg:String, messageActorMap: HashMap[String, MessageActor]) extends Actor { def act() { loop { react { case MessageActorCreator(messageId, messageActorMap) = if(messageId != null ) { var messageActor = new MessageActor(messageId); messageActorMap.put(messageId, messageActor) println(messageActorMap) messageActor.start messageActor ! MessageActor } } } } } class LoopControl(messageReceiver:MessageReceiver) extends Actor { var count : Int = 0; def act() { while (true) { messageReceiver ! MessageActor ("00-122-0X95-FEC0" + count) //Thread.sleep(100) count = count +1; if(count 5) { count = 0; } } } } case class MessageActor(msg: String) extends Actor { def act() { loop { react { case MessageActor = println() println("MessageActor: Got something- " + msg) } } } } object messages extends Application { val messageReceiver = new MessageReceiver("bootstrap") val loopControl = new LoopControl(messageReceiver) messageReceiver.start loopControl.start }

  Read the article

• Mingling C++ classes with Objective C classes

  - by Joey

  I am using the iphone SDK and coding primarily in C++ while using parts of the SDK in obj-c. Is it possible to designate a C++ class in situations where an obj-c class is needed? For instance: 1) when setting delegates to obj-c objects. I cannot make a C++ class derive from a Delegate protocol so this and possibly other reasons prevent me from making my C++ class a delegate for various obj-c objects. What I do as a solution is create an obj-c adapter class that contains a ptr to the C++ class and is used as the delegate (notifying the C++ class when it is called). It feels cumbersome to write these every time I need to get delegate notifications to a C++ class. 2) when setting selectors This goes hand in hand with item 1. Say I want to set a callback to fire when something is done, like a button press or a setAnimationDidStopSelector in the UIView animation functionality. It would be nice to be able to designate a C++ function along with the relevant delegate for setAnimationDelegate. Well, I suspect this isn't readily possible, but if anyone has any suggestions on how to do it if it is, or on how to write such things more easily, I would love to hear them. Thanks.

  Read the article

• Object created in Interface Builder getting dealloc'ed too soon

  - by Collin Allen

  The Project I'm working on a relatively simple iPhone OS project that's navigation controller based, with a root table view and a detail table view. Tap an item in the main list to see its details in a pushed table view. The Setup I broke out the data source for both views into their own objects so as not to muddy the purpose of a view controller. Having done this, the table views no longer have data sources since those methods are now in separate files, so I created an instance of each data source class in the appropriate XIB files with the Object item (dragged it in, then set its class). Then, to actually connect the tableviews to their data sources, I set the dataSource outlet of each tableview to the yellow data source object in Interface Builder. The table view delegates are still set to their view controllers. The Problem The root table view works just fine, but when you tap a row to push to the detail view, the data source object gets instantiated as expected, then immediately dealloc'ed, causing a crash (numberOfSectionsInTableView: gets called on the freed object). I can't figure out why the data source is getting automatically dealloc-ed when I need it right then and there for the detail view, as indicated by my data source object creation and tableview connection in Interface Builder. What's more perplexing is that the very approach works fine for the root tableview! The Question Is there anything obvious I'm missing that would cause this to happen? Or, is this even the right way to instantiate a data source for a table view controller? It seems like poor object oriented programming to do it from within the view controller, which should only be concerned with the view. I could cram everything in two table view controller classes and it would probably work, but it would not be as modular as I'd like. Thanks!

  Read the article

• How do I avoid repetition in Java ResourceBundle strings?

  - by Trejkaz

  We had a lot of strings which contained the same sub-string, from sentences about checking the log or how to contact support, to branding-like strings containing the company or product name. The repetition was causing a few issues for ourselves (primarily typos or copy/paste errors) but it also causes issues in that it increases the amount of text our translator has to translate. The solution I came up with went something like this: public class ExpandingResourceBundleControl extends ResourceBundle.Control { public static final ResourceBundle.Control EXPANDING = new ExpandingResourceBundleControl(); private ExpandingResourceBundleControl() { } @Override public ResourceBundle newBundle(String baseName, Locale locale, String format, ClassLoader loader, boolean reload) throws IllegalAccessException, InstantiationException, IOException { ResourceBundle inner = super.newBundle(baseName, locale, format, loader, reload); return inner == null ? null : new ExpandingResourceBundle(inner, loader); } } ExpandingResourceBundle delegates to the real resource bundle but performs conversion of {{this.kind.of.thing}} to look up the key in the resources. Every time you want to get one of these, you have to go: ResourceBundle.getBundle("com/acme/app/Bundle", EXPANDING); And this works fine -- for a while. What eventually happens is that some new code (in our case autogenerated code which was spat out of Matisse) looks up the same resource bundle without specifying the custom control. This appears to be non-reproducible if you write a simple unit test which calls it with and then without, but it occurs when the application is run for real. Somehow the cache inside ResourceBundle ejects the good value and replaces it with the broken one. I am yet to figure out why and Sun's jar files were compiled without debug info so debugging it is a chore. My questions: Is there some way of globally setting the default ResourceBundle.Control that I might not be aware of? That would solve everything rather elegantly. Is there some other way of handling this kind of thing elegantly, perhaps without tampering with the ResourceBundle classes at all?

  Read the article

• Handling events from user control containing a WPF textbox

  - by Tom

  I've been successful in putting a WPF textbox into an existing windows form using ElementHost and a user control. It looks like the following: Public Class MyUserControl Private _elementHost as ElementHost = New ElementHost Private _wpfTextbox as System.Windows.Controls.Textbox = New System.Windows.Controls.Textbox Public Sub New() Me.Controls.Add(_elementHost) _elementHost.Dock = DockStyle.Fill _elementHost.Child = _wpfTextbox _wpfTextbox.SpellCheck.IsEnabled = True End Sub End Class Now, when I put this user control onto a windows form, it accepts keyboard input and the form itself can get text from the textbox. However, when I try to handle keypress (or keydown, keyup) events from the user control, nothing happens. I've looked into this problem and did a bit of research but now I'm a little confused as to what I really need to be looking at. The following are the topics that I am somewhat confused about. HwndSource Relaxed delegates WPF routed events If I am interpreting everything correctly, input from WPF textboxes are handled differently compared to regular form textboxes. It seems like both aren't compatible with each other but there must be some way to "pass" keys from one to another? I'd appreciate any help.

  Read the article

• are there code signing certificates cheaper than US $99 per year? [closed]

  - by gerryLowry

  ksoftware discounts Commodo code signing certificates to US $99 per year. in the past, I've seen Commodo code signing certificates for US $80. I'm excluding CAcert which AFAIK are FREE but are not covered by browsers like IE AFAIK. QUESTION: What is the best price per year for a code signing certificate? Thank you ~~ gerry (lowry) Edit: **THIS SHOULD NOT HAVE BEEN CLOSED** from the FAQ: http://stackoverflow.com/faq ---------------------------- What kind of questions can I ask here? Programming questions, of course! As long as your question is: * detailed and specific <====== YES! * written clearly and simply <====== YES! * of interest to other programmers <====== YES! I've been programming for over 40 years. http://gerrylowryprogrammer.com/ I've taught computer programming at the community college level. I'm a Star level contributer to forums.asp.net. http://forums.asp.net/members/gerrylowry.aspx imo, I've a very good idea what is of interest to other programmers. MORE INFORMATION Ensuring the integrity of code and executables that one distributes is just as much about programming as is knowing how to flip bits in assembler, use delegates in c#, and use the BDD context/specification still of "test first testing".

  Read the article

• Good patterns for loose coupling in Java?

  - by Eye of Hell

  Hello. I'm new to java, and while reading documentation so far i can't find any good ways for programming with loose coupling between objects. For majority of languages i know (C++, C#, python, javascript) i can manage objects as having 'signals' (notification about something happens/something needed) and 'slots' (method that can be connected to signal and process notification/do some work). In all mentioned languages i can write something like this: Object1 = new Object1Class(); Object2 = new Object2Class(); Connect( Object1.ItemAdded, Object2.OnItemAdded ); Now if object1 calls/emits ItemAdded, the OnItemAdded method of Object2 will be called. Such loose coupling technique is often referred as 'delegates', 'signal-slot' or 'inversion of control'. Compared to interface pattern, technique mentioned don't need to group signals into some interfaces. Any object's methods can be connected to any delegate as long as signatures match ( C++Qt even extends this by allowing only partial signature match ). So i don't need to write additional interface code for each methods / groups of methods, provide default implementation for interface methods not used etc. And i can't see anything like this in Java :(. Maybe i'm looking a wrong way?

  Read the article

• Factory Method Pattern clarification

  - by nettguy

  My understanding of Factory Method Pattern is (Correct me if i am wrong) Factory Method Pattern "Factory Method allow the client to delegates the product creation (Instance Creation) to the subclass". There are two situation in which we can go for creating Factory Method pattern. (i) When the client is restricted to the product (Instance) creation. (ii) There are multiple products available.But a decision to be made which product instance need to be returned. If you want to create Abstract Method pattern You need to have abstract product Concrete Product Factory Method to return the appropriate product. Example : public enum ORMChoice { L2SQL, EFM, LS, Sonic } //Abstract Product public interface IProduct { void ProductTaken(); } //Concrete Product public class LinqtoSql : IProduct { public void ProductTaken() { Console.WriteLine("OR Mapping Taken:LinqtoSql"); } } //concrete product public class Subsonic : IProduct { public void ProductTaken() { Console.WriteLine("OR Mapping Taken:Subsonic"); } } //concrete product public class EntityFramework : IProduct { public void ProductTaken() { Console.WriteLine("OR Mapping Taken:EntityFramework"); } } //concrete product public class LightSpeed : IProduct { public void ProductTaken() { Console.WriteLine("OR Mapping Taken :LightSpeed"); } } public class Creator { //Factory Method public IProduct ReturnORTool(ORMChoice choice) { switch (choice) { case ORMChoice.EFM:return new EntityFramework(); break; case ORMChoice.L2SQL:return new LinqtoSql(); break; case ORMChoice.LS:return new LightSpeed(); break; case ORMChoice.Sonic:return new Subsonic(); break; default: return null; } } } **Client** Button_Click() { Creator c = new Creator(); IProduct p = c.ReturnORTool(ORMChoice.L2SQL); p.ProductTaken(); } Is my understanding of Factory Method is correct?

  Read the article

• Interface and partial classes

  - by Tomek Tarczynski

  According to rule SA1201 in StyleCop elements in class must appear in correct order. The order is following: Fields Constructors Finalizers (Destructors) Delegates Events Enums Interfaces Properties Indexers Methods Structs Classes Everything is ok, except of Interfaces part, because Interface can contain mehtods, events, properties etc... If we want to be strict about this rule then we won't have all members of Interface in one place which is often very useful. According to StyleCop help this problem can be solved by spliting class into partial classes. Example: /// <summary> /// Represents a customer of the system. /// </summary> public partial class Customer { // Contains the main functionality of the class. } /// <content> /// Implements the ICollection class. /// </content> public partial class Customer : ICollection { public int Count { get { return this.count; } } public bool IsSynchronized { get { return false; } } public object SyncRoot { get { return null; } } public void CopyTo(Array array, int index) { throw new NotImplementedException(); } } Are there any other good solutions to this problem?

  Read the article

• Where and how to start on C# and .Net Framework ?

  - by Rachel

  Currently, I have been working as an PHP developer for approximately 1 year now and I want learn about C# and .Net Framework, I do not have any experience with .Net Framework and C# and also there is not firm basis as to why I am going for C# and .Net Framework vs Java or any other programming languages, this decision is mere on career point of view and job opportunities. So my question is about: Is my decision wise to go for C# and .Net Framework route after working for sometime as an PHP Developer ? What are the good resources which I can refer and learn from to get knowledge on C# and .NET Framework ? How should I go about learning on C# and .NET Framework ? What all technologies should I be learning OR have experience with to be considered as an C#/.Net Developer, I am mentioning some technologies, please add or suggest one, if am missing out any ? Technologies C#-THE LANGUAGE GUI APPLICATION DEVELOPMENT WINDOWS CONTROL LIBRARY DELEGATES DATA ACCESS WITH ADO.NET MULTI THREADING ASSEMBLIES WINDOWS SERVICES VB INTRODUCTION TO VISUAL STUDIO .NET WINDOWS CONTROL LIBRARY DATA ACCESS WITH ADO.NET ASP.NET WEB TECHNOLOGIES CONTROLS VALIDATION CONTROL STATE MANAGEMENT CACHING ASP.NET CONFIGURATION ADO.NET ASP.NET TRACING & SECURITY IN ASP.NET XMLPROGRAMMING WEB SERVICES CRYSTAL REPORTS SSRS (SQL Server Reporting Services) MS-Reports LINQ: NET Language-Integrated Query NET Language-Integrated Query LINQ to SQL: SQL Integration WCF: Windows Communication Foundation What Is Windows Communication Foundation? Fundamental Windows Communication Foundation Concepts Windows Communication Foundation Architecture WPF: Windows Presentation Foundation Getting Started (WPF) Application Development WPF Fundamentals What are your thoughts, suggestions on this and from Job and Market Perspective, what areas of C#/.Net Development should I put my focus on ? I know this is very subjective and long question but advice would be highly appeciated. Thanks.

  Read the article

• Is there a library that can decompile a method into an Expression tree, with support for CLR 4.0?

  - by Daniel Earwicker

  Previous questions have asked if it is possible to turn compiled delegates into expression trees, for example: http://stackoverflow.com/questions/767733/converting-a-net-funct-to-a-net-expressionfunct The sane answers at the time were: It's possible, but very hard and there's no standard library solution. Use Reflector! But fortunately there are some greatly-insane/insanely-great people out there who like reverse engineering things, and they make difficult things easy for the rest of us. Clearly it is possible to decompile IL to C#, as Reflector does it, and so you could in principle instead target CLR 4.0 expression trees with support for all statement types. This is interesting because it wouldn't matter if the compiler's built-in special support for Expression<> lambdas is never extended to support building statement expression trees in the compiler. A library solution could fill the gap. We would then have a high-level starting point for writing aspect-like manipulations of code without having to mess with raw IL. As noted in the answers to the above linked question, there are some promising signs but I haven't succeeded in finding if there's been much progress since by searching. So has anyone finished this job, or got very far with it? Note: CLR 4.0 is now released. Time for another look-see.

  Read the article

• Is it safe to reuse javax.xml.ws.Service objects

  - by Noel Ang

  I have JAX-WS style web service client that was auto-generated with the NetBeans IDE. The generated proxy factory (extends javax.xml.ws.Service) delegates proxy creation to the various Service.getPort methods. The application that I am maintaining instantiates the factory and obtains a proxy each time it calls the targetted service. Creating the new proxy factory instances repeatedly has been shown to be expensive, given that the WSDL documentation supplied to the factory constructor, an HTTP URI, is re-retrieved for each instantiation. We had success in improving the performance by caching the WSDL. But this has ugly maintenance and packaging implications for us. I would like to explore the suitability of caching the proxy factory itself. Is it safe, e.g., can two different client classes, executing on the same JVM and targetting the same web service, safely use the same factory to obtain distinct proxy objects (or a shared, reentrant one)? I've been unable to find guidance from either the JAX-WS specification nor the javax.xml.ws API documentation. The factory-proxy multiplicity is unclear to me. Having Service.getPort rather than Service.createPort does not inspire confidence.

  Read the article

• java partial classes

  - by Dewfy

  Hello colleagues, Small preamble. I was good java developer on 1.4 jdk. After it I have switched to another platforms, but here I come with problem so question is strongly about jdk 1.6 (or higher :) ). I have 3 coupled class, the nature of coupling concerned with native methods. Bellow is example of this 3 class public interface A { public void method(); } final class AOperations { static native method(. . .); } public class AImpl implements A { @Override public void method(){ AOperations.method( . . . ); } } So there is interface A, that is implemented in native way by AOperations, and AImpl just delegates method call to native methods. These relations are auto-generated. Everything ok, but I have stand before problem. Sometime interface like A need expose iterator capability. I can affect interface, but cannot change implementation (AImpl). Saying in C# I could be able resolve problem by simple partial: (C# sample) partial class AImpl{ ... //here comes auto generated code } partial class AImpl{ ... //here comes MY implementation of ... //Iterator } So, has java analogue of partial or something like.

  Read the article

• UIWebView: webViewDidStartLoad/webViewDidFinishLoad delegate methods not called when loading certain URLs

  - by Dia

  I have basic web browser implemented using a UIWebView. I've noticed that for some pages, none of the UIWebViewDelegate methods are called. An example page in which this happens is: http://www.youtube.com/user/google. Here are the steps to reproduce the issue (make sure you insert NSLog calls in your controller's UIWebViewDelegate methods): Load the above youtube URL into the UIWebView [notice that here, the UIWebViewDelegate methods do get called when the page loads] Touch the "Uploads" category on the page Touch any video in that category [issue: notice that a new page is loaded, but none of the UIWebView delegates are called] I know that this is not an issue of UIWebView's delegate not being set properly, since the delegate methods do get invoked when loading other links (e.g. if you try clicking on a link that takes you outside of youtube, you'll notice the delegate methods getting called). My gut feeling initially was that it might be because the page is loaded using AJAX, which may not invoke the delegate method. But then when I checked Safari, it did not exhibit this problem, so it must be something on my side. I've also noticed that Three20's TTWebController has the exact same issue as I'm having. But the problem that arises from this issue is that without the delegate methods called, I'm unable to update the UI to enable/disable the back and forward browsing buttons when new requests are loaded. And idea why this is happening or how can I work around it to update the UI when a new request is made?

  Read the article

• How do I run a universal app on the iPhone 3.1.3 simulator?

  - by bpapa

  I'm working on a new app that I want to be universal for the iPhone and iPad. I started out with the "Create a Window-based app" wizard, and it created separate app delegates in "iPhone" and "iPad" groups. Since I already was quite familiar with iPhone dev, I did that part of my project, and now I'm ready to do some iPad stuff. So... I started out by adding a UISplitViewController to my iPad delegate, switch the Active SDK to 3.2, and it works! But when I switch back to 3.1.3, and try to run it in the simulator, Build and Go fails. For starters, I see: ...path.../iPad/AppDelegate_Pad.h:13: error: expected specifier-qualifier-list before 'UISplitViewController' I've got my Base SDK set to 3.2 and my Deployment Target set to 3.1.3. I thought that was enough. But I also have found in the documentation this method to conditionally compile: #if __IPHONE_OS_VERSION_MAX_ALLOWED >= 30200 MyIPadViewController* vc; // Create the iPad view controller #else MyIPhoneViewController* vc; // Create the iPhone view controller #endif So do I need to do this everywhere? It seems like an awful lot of code to add (that I'll be getting rid of in a short time for 4.0 anyway) so I feel like I must be doing something wrong. And, I don't even have any idea how this works for things like @property or @synthesize declarations. tl;dr version of the question - did I miss a setting somewhere?

  Read the article

• NSPredicate cause update editing to return NSFetchedResultsChangeDelete not NSFetchedResultsChangeUp

  - by Matthew Weiss

  I have predicate inside of - (NSFetchedResultsController *)fetchedResultsController in a standard way starting from the CoreDataBook example. NSPredicate *predicate = [NSPredicate predicateWithFormat:@"state=%@ && date = %@ && date < %@", @"1",fromDate,toDate]; [fetchRequest setPredicate:predicate]; This works fine however when editing an item, it returns with NSFetchedResultsChangeDelete not Update. When the main view returns, it is missing the item. If I restart the simulator the delete was not saved and the correct editing result is shown the the predicate working correctly. case NSFetchedResultsChangeDelete: [tableView deleteRowsAtIndexPaths:[NSArray arrayWithObject:indexPath] withRowAnimation:UITableViewRowAnimationFade]; break; I can confirm the behavior by commenting out the two predicate lines ONLY and then all works as it should correctly returning with the full set after editing and calling NSFetchedResultsChangeUpdate instead of NSFetchedResultsChangeDelete. I have read http://matteocaldari.it/2009/11/multiple-contexts-controllers-delegates-and-coredata-bug who reports similar behavior but I have not found a work around to my problem. I can

  Read the article

• .net layered design: return error code to forms indicating which controls have an error

  - by David Casillas

  Let's say I have a simple application. It tries to add a new entry to a database grabing the info from the user. The information is a tipical MasterDetail objetc like an invoice. The Invoice object used to collect the data has some simple atributes (Id, Date, etc...) and a List of InvoiceDetail, consisting of some simple atributes (invoiceId, productId, quantity, etc...) A form in the UI Layer collects the data from the user, creates an instance of Invoice and sends it to the Bussiness Layer. The Bussines layer sends the data to a Validation Module. If any error in the input is detected it has to return some kind of error code. The Bussiness Layer has to send the error code back to the Form to let the user correct the worng information. I want the application to display some kind of warning (a different background color for example) in every form control with an error. ¿What's a good aproach to I manage the errors to be able to inform the form which controls are wrong? ¿Can I create an error object?¿Use delegates?. I'm using VB.net but don't think this is relevant to the solution of the problem. P.D: Please suggest me some tags to this post.

  Read the article

• What should I do if i have a factory method which requires different parameters for different implem

  - by Sam Holder

  I have an interface, IMessage and a class which have several methods for creating different types of message like so: class MessageService { IMessage TypeAMessage(param 1, param 2) IMessage TypeBMessage(param 1, param 2, param 3, param 4) IMessage TypeCMessage(param 1, param 2, param 3) IMessage TypeDMessage(param 1) } I don't want this class to do all the work for creating these messages so it simply delegates to a MessageCreatorFactory which produces an IMessageCreator depending on the type given (an enumeration based on the type of the message TypeA, TypeB, TypeC etc) interface IMessageCreator { IMessage Create(MessageParams params); } So I have 4 implementations of IMessageCreator: TypeAMessageCreator, TypeBMessageCreator, TypeCMessageCreator, TypeDMessageCreator I ok with this except for the fact that because each type requires different parameters I have had to create a MessageParams object which contains 4 properties for the 4 different params, but only some of them are used in each IMessageCreator. Is there an alternative to this? One other thought I had was to have a param array as the parameter in the Create emthod, but this seems even worse as you don't have any idea what the params are. Or to create several overloads of Create in the interface and have some of them throw an exception if they are not suitable for that particular implementation (ie you called a method which needs more params, so you should have called one of the other overloads.) Does this seem ok? Is there a better solution?

  Read the article

• C# delegate or Func for 'all methods'?

  - by Michel

  Hi, i've read something about Func's and delegates and that they can help you to pass a method as a parameter. Now i have a cachingservice, and it has this declaration: public static void AddToCache<T>(T model, double millisecs, string cacheId) where T : class public static T GetFromCache<T>(string cacheId) where T : class So in a place where i want to cache some data, i check if it exists in the cache (with GetFromCache) and if not, get the data from somewhere, and the add it to the cache (with AddToCache) Now i want to extend the AddToCache method with a parameter, which is the class+method to call to get the data Then the declaration would be like this public static void AddToCache<T>(T model, double millisecs, string cacheId, Func/Delegate methode) where T : class Then this method could check wether the cache has data or not, and if not, get the data itself via the method it got provided. Then in the calling code i could say: AddToCache<Person>(p, 10000, "Person", new PersonService().GetPersonById(1)); AddToCache<Advert>(a, 100000, "Advert", new AdvertService().GetAdverts(3)); What i want to achieve is that the 'if cache is empty get data and add to cache' logic is placed on only one place. I hope this makes sense :) Oh, by the way, the question is: is this possible?

  Read the article

• How to copy generically superclass instances to subclass instances?

  - by gerry

  Hi @all, I have a class hierarchy / inheritance like this: public class A { private String name; // with getters & setters public void doAWithName(){ ... } } public class B extends A { public void doBWithName(){ // a differnt implementation to what I do in class A } } public class C extends B { public void doCWithName(){ // a differnt implementation to what I do in class A and B } } So at one time there is a instance of class A with the initialized field "name". Later I want this instance of A get wrapped into instance of B or C. So the superclasses should be get wrapped with a subclass! How can I make this most efficent with respect to DRY? I've thought about a constructor that does some copying with the getters/setters. But in this case I have to repeat myself - and this doesn't respect anymore to my initial requirement of DRY! So, how can I warp A to B by just initializing B's new fields (with default values) and delegating the rest to a method in A (which knows more than B about which fields of A should be accessed...). In the same way: If A should be wrapped into C only a method in c should init C's 'new' fields, delegate to B's wrap method (which therefore inits B's 'new' fields in C) and at last B delegates to A which copies it's fields to the fields of C). So in the end I have a new instance of C which has the values of A wrapped (and some default init values to the fields which the inheritance hierarchy has added).

  Read the article

• Scala newbie vproducer/consumer attempt running out of memory

  - by Nick

  I am trying to create a producer/consumer type Scala app. The LoopControl just sends a message to the MessageReceiver continually. The MessageReceiver then delegates work to the MessageCreatorActor (whose work is to check a map for an object, and if not found create one and start it up). Each MessageActor created by this MessageCreatorActor is associated with an Id. Eventually this is where I want to do business logic. But I run out of memory after 15 minutes. Its finding the cached actors,but quickly runs out of memory. Any help is appreciated. Or any one has any good code on producers consumers doing real stuff (not just adding numbers), please post. import scala.actors.Actor import java.util.HashMap import scala.actors.Actor._ case object LoopControl case object MessageReceiver case object MessageActor case object MessageActorCreator class MessageReceiver(msg: String) extends Actor { var messageActorMap = new HashMap[String, MessageActor] val messageCreatorActor = new MessageActorCreator(null, null) def act() { messageCreatorActor.start loop { react { case MessageActor(messageId) => if (msg.length() > 0) { var messageActor = messageActorMap.get(messageId); if(messageActor == null) { messageCreatorActor ! MessageActorCreator(messageId, messageActorMap) }else { messageActor ! MessageActor } } } } } } case class MessageActorCreator(msg:String, messageActorMap: HashMap[String, MessageActor]) extends Actor { def act() { loop { react { case MessageActorCreator(messageId, messageActorMap) => if(messageId != null ) { var messageActor = new MessageActor(messageId); messageActorMap.put(messageId, messageActor) println(messageActorMap) messageActor.start messageActor ! MessageActor } } } } } class LoopControl(messageReceiver:MessageReceiver) extends Actor { var count : Int = 0; def act() { while (true) { messageReceiver ! MessageActor ("00-122-0X95-FEC0" + count) //Thread.sleep(100) count = count +1; if(count > 5) { count = 0; } } } } case class MessageActor(msg: String) extends Actor { def act() { loop { react { case MessageActor => println() println("MessageActor: Got something-> " + msg) } } } } object messages extends Application { val messageReceiver = new MessageReceiver("bootstrap") val loopControl = new LoopControl(messageReceiver) messageReceiver.start loopControl.start }

  Read the article

• Custom Swing component: questions on approach

  - by phatmanace

  Hi Folks, I'm trying to build a new java swing component, I realise that I might be able to find one that does what I need on the web, but this is partly an exercise for me to learn ow to do this. I want to build a swing component that represents a Gantt chart. it would be good (though not essential for people to be able to interact with it (e.g slide the the tasks around to adjust timings) it feels like the best approach for this is to subclass JComponent, and override PaintComponent() to 'draw a picture' of what the chart should look like, as opposed to doing something like trying to jam everything into a custom JTable. I've read a couple of books on the subject, and also looked at a few examples (most notably things like JXGraph) - but I'm curious about a few things When do I have to switch to using UI delegates, and when can I stick to just fiddling around in paintcomponent() to render what I want? if I want other swing components as sub-elements of my component (e.g I wanted a text box on my gantt chart) can I no longer use paintComponent()? can I arbitrarily position them within my Gantt chart, or do I have to use a normal swing layout manager many thanks in advance. -Ace

  Read the article

< Previous Page | 15 16 17 18 19 20 21 22 23 24  | Next Page >