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  • what should be the return type of the hashCode()

    - by subhashis
    The signature of the hashCode() method is public int hashCode(){ return x; } in this case x must be an int(primitive) but plz can anyone explain it to me that the number which the hashCode() returns must be a prime number, even number...etc or there is no specification ? the reason behind i am asking this question is i have seen it in different ids the auto generated code always returns a prime number, so i need to know why? thanks in advance

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  • Casting Type array to Generic array?

    - by George R
    The short version of the question - why can't I do this? I'm restricted to .NET 3.5. T[] genericArray; // Obviously T should be float! genericArray = new T[3]{ 1.0f, 2.0f, 0.0f }; // Can't do this either, why the hell not genericArray = new float[3]{ 1.0f, 2.0f, 0.0f }; Longer version - I'm working with the Unity engine here, although that's not important. What is - I'm trying to throw conversion between its fixed Vector2 (2 floats) and Vector3 (3 floats) and my generic Vector< class. I can't cast types directly to a generic array. using UnityEngine; public struct Vector { private readonly T[] _axes; #region Constructors public Vector(int axisCount) { this._axes = new T[axisCount]; } public Vector(T x, T y) { this._axes = new T[2] { x, y }; } public Vector(T x, T y, T z) { this._axes = new T[3]{x, y, z}; } public Vector(Vector2 vector2) { // This doesn't work this._axes = new T[2] { vector2.x, vector2.y }; } public Vector(Vector3 vector3) { // Nor does this this._axes = new T[3] { vector3.x, vector3.y, vector3.z }; } #endregion #region Properties public T this[int i] { get { return _axes[i]; } set { _axes[i] = value; } } public T X { get { return _axes[0];} set { _axes[0] = value; } } public T Y { get { return _axes[1]; } set { _axes[1] = value; } } public T Z { get { return this._axes.Length (Vector2 vector2) { Vector vector = new Vector(vector2); return vector; } public static explicit operator Vector(Vector3 vector3) { Vector vector = new Vector(vector3); return vector; } #endregion }

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  • Type-casting. C and C++

    - by thecoshman
    I always though that float var_a = 9.99; int var_b = (int)var_a; was they way to typecast in c++... But here it said that its not the proper C++ way, its the old C way. So I ask, What is the proper C++ way, and more importantly, how do they differ? the C method should still work though shouldn't it.

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  • Eclipse - How to show warning for unused method parameter ?

    - by Brad
    I am using Eclipse v3.5. In previous Eclipse versions i remember if i have defined a method with a parameter and didn't use it internally a warning appears, like this : public void myMethod( int x ) { // Didn't use x here so a warning appears at the x parameter. } But in v3.5 i do not see this warning. How can i enable it in Eclipse ?

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  • ActionScript Custom Class With Return Type?

    - by TheDarkIn1978
    i just know this is a dumb question, so excuse me in advance. i want to essentially classify a simple function in it's own .as file. the function compares integers. but i don't know how to call the class and receive a boolean return. here's my class package { public class CompareInts { public function CompareInts(small:int, big:int) { compare(small, big); } private function compare(small:int, big:int):Boolean { if (small < big) return true; else return false; } } } so now i'd like to write something like this: if (CompareInts(1, 5) == true). or output 'true' by writing trace(CompareInts(1, 5));

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  • Do I really need to return Type::size_type?

    - by dehmann
    I often have classes that are mostly just wrappers around some STL container, like this: class Foo { public: typedef std::vector<whatever> Vec; typedef Vec::size_type; const Vec& GetVec() { return vec_; } size_type size() { return vec_.size() } private: Vec vec_; }; I am not so sure about returning size_type. Often, some function will call size() and pass that value on to another function and that one will use it and maybe pass it on. Now everyone has to include that Foo header, although I'm really just passing some size value around, which should just be unsigned int anyway ...? What is the right thing to do here? Is it best practice to really use size_type everywhere?

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  • Passing Parameters to an ADF Page through the URL - Part 2.

    - by shay.shmeltzer
    I showed before how to pass a parameter on the URL when invoking a taskflow (where the taskflow starts with a method call and then a page). However in some simpler scenarios you don't actually need a full blown taskflow. Instead you can use page level parameters defined for your page in the adfc-config.xml file. So below is a demo of this technique. I'm also taking advantage of this video to show the concept of a view object level service method and how to invoke it from your page. P.S. You might wonder - why not just reference #{param.amount} as the value set for the method parameter? Why do I need to copy it into a viewScope parameter? The advantage of placing the value in the viewScope is that it is available even when the page went through several sumbits. For example if you switch the "partialSumbit" property of the "Next" button to false in the above example - the minute that you press the button to go to the next department - the param.amount value is gone. However the ViewScope is still there as long as you stay on this page.

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  • XNA - Inconsistent accessibility: parameter type is less accessible than method

    - by DijkeMark
    I have a level class in which I make a new turret. I give the turret the level class as parameter. So far so good. Then in the Update function of the Turret I call a function Shoot(), which has that level parameter it got at the moment I created it. But from that moment it gives the following error: Inconsistent accessibility: parameter type 'Space_Game.Level' is less accessible than method 'Space_Game.GameObject.Shoot(Space_Game.Level, string)' All I know it has something to do with not thr right protection level or something like that. The level class: public Level(Game game, Viewport viewport) { _game = game; _viewport = viewport; _turret = new Turret(_game, "blue", this); _turret.SetPosition((_viewport.Width / 2).ToString(), (_viewport.Height / 2).ToString()); } The Turret Class: public Turret(Game game, String team, Level level) :base(game) { _team = team; _level = level; switch (_team) { case "blue": _texture = LoadResources._blue_turret.Texture; _rows = LoadResources._blue_turret.Rows; _columns = LoadResources._blue_turret.Columns; _maxFrameCounter = 10; break; default: break; } _frameCounter = 0; _currentFrame = 0; _currentFrameMultiplier = 1; } public override void Update() { base.Update(); SetRotation(); Shoot(_level, "turret"); } The Shoot Function (Which is in GameObject class. The Turret Class inherited the GameObject Class. (Am I saying that right?)): protected void Shoot(Level level, String type) { MouseState mouse = Mouse.GetState(); if (mouse.LeftButton == ButtonState.Pressed) { switch (_team) { case "blue": switch (type) { case "turret": TurretBullet _turretBullet = new TurretBullet(_game, _team); level.AddProjectile(_turretBullet); break; default: break; } break; default: break; } } } Thanks in Advance, Mark Dijkema

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  • 5 Android Keyboard Replacements to Help You Type Faster

    - by Chris Hoffman
    Android allows developers to replace its keyboard with their own keyboard apps. This has led to experimentation and great new features, like the gesture-typing feature that’s made its way into Android’s official keyboard after proving itself in third-party keyboards. This sort of customization isn’t possible on Apple’s iOS or even Microsoft’s modern Windows environments. Installing a third-party keyboard is easy — install it from Google Play, launch it like another app, and it will explain how to enable it. Google Keyboard Google Keyboard is Android’s official keyboard, as seen on Google’s Nexus devices. However, there’s a good chance your Android smartphone or tablet comes with a keyboard designed by its manufacturer instead. You can install the Google Keyboard from Google Play, even if your device doesn’t come with it. This keyboard offers a wide variety of features, including a built-in gesture-typing feature, as popularized by Swype. It also offers prediction, including full next-word prediction based on your previous word, and includes voice recognition that works offline on modern versions of Android. Google’s keyboard may not offer the most accurate swiping feature or the best autocorrection, but it’s a great keyboard that feels like it belongs in Android. SwiftKey SwiftKey costs $4, although you can try it free for one month. In spite of its price, many people who rarely buy apps have been sold on SwiftKey. It offers amazing auto-correction and word-prediction features. Just mash away on your touch-screen keyboard, typing as fast as possible, and SwiftKey will notice your mistakes and type what you actually meant to type. SwiftKey also now has built-in support for gesture-typing via SwiftKey Flow, so you get a lot of flexibility. At $4, SwiftKey may seem a bit pricey, but give the month-long trial a try. A great keyboard makes all the typing you do everywhere on your phone better. SwiftKey is an amazing keyboard if you tap-to-type rather than swipe-to-type. Swype While other keyboards have copied Swype’s swipe-to-type feature, none have completely matched its accuracy. Swype has been designing a gesture-typing keyboard for longer than anyone else and its gesture feature still seems more accurate than its competitors’ gesture support. If you use gesture-typing all the time, you’ll probably want to use Swype. Swype can now be installed directly from Google Play without the old, tedious process of registering a beta account and sideloading the Swype app. Swype offers a month-long free trial and the full version is available for $1 afterwards. Minuum Minuum is a crowdfunded keyboard that is currently still in beta and only supports English. We include it here because it’s so interesting — it’s a great example of the kind of creativity and experimentation that happens when you allow developers to experiment with their own forms of keyboard. Minuum uses a tiny, minimum keyboard that frees up your screen space, so your touch-screen keyboard doesn’t hog your device’s screen. Rather than displaying a full keyboard on your screen, Minuum displays a single row of letters.  Each letter is small and may be difficult to hit, but that doesn’t matter — Minuum’s smart autocorrection algorithms interpret what you intended to type rather than typing the exact letters you press. Just swipe to the right to type a space and accept Minuum’s suggestion. At $4 for a beta version with no trial, Minuum may seem a bit pricy. But it’s a great example of the flexibility Android allows. If there’s a problem with this keyboard, it’s that it’s a bit late — in an age of 5″ smartphones with 1080p screens, full-size keyboards no longer feel as cramped. MessagEase MessagEase is another example of a new take on text input. Thankfully, this keyboard is available for free. MessagEase presents all letters in a nine-button grid. To type a common letter, you’d tap the button. To type an uncommon letter, you’d tap the button, hold down, and swipe in the appropriate direction. This gives you large buttons that can work well as touch targets, especially when typing with one hand. Like any other unique twist on a traditional keyboard, you’d have to give it a few minutes to get used to where the letters are and the new way it works. After giving it some practice, you may find this is a faster way to type on a touch-screen — especially with one hand, as the targets are so large. Google Play is full of replacement keyboards for Android phones and tablets. Keyboards are just another type of app that you can swap in. Leave a comment if you’ve found another great keyboard that you prefer using. Image Credit: Cheon Fong Liew on Flickr     

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  • WPF unity Activation error occured while trying to get instance of type

    - by Traci
    I am getting the following error when trying to Initialise the Module using Unity and Prism. The DLL is found by return new DirectoryModuleCatalog() { ModulePath = @".\Modules" }; The dll is found and the Name is Found #region Constructors public AdminModule( IUnityContainer container, IScreenFactoryRegistry screenFactoryRegistry, IEventAggregator eventAggregator, IBusyService busyService ) : base(container, screenFactoryRegistry) { this.EventAggregator = eventAggregator; this.BusyService = busyService; } #endregion #region Properties protected IEventAggregator EventAggregator { get; set; } protected IBusyService BusyService { get; set; } #endregion public override void Initialize() { base.Initialize(); } #region Register Screen Factories protected override void RegisterScreenFactories() { this.ScreenFactoryRegistry.Register(ScreenKeyType.ApplicationAdmin, typeof(AdminScreenFactory)); } #endregion #region Register Views and Various Services protected override void RegisterViewsAndServices() { //View Models this.Container.RegisterType<IAdminViewModel, AdminViewModel>(); } #endregion the code that produces the error is: namespace Microsoft.Practices.Composite.Modularity protected virtual IModule CreateModule(string typeName) { Type moduleType = Type.GetType(typeName); if (moduleType == null) { throw new ModuleInitializeException(string.Format(CultureInfo.CurrentCulture, Properties.Resources.FailedToGetType, typeName)); } return (IModule)this.serviceLocator.GetInstance(moduleType); <-- Error Here } Can Anyone Help Me Error Log Below: General Information Additional Info: ExceptionManager.MachineName: xxxxx ExceptionManager.TimeStamp: 22/02/2010 10:16:55 AM ExceptionManager.FullName: Microsoft.ApplicationBlocks.ExceptionManagement, Version=1.0.3591.32238, Culture=neutral, PublicKeyToken=null ExceptionManager.AppDomainName: Infinity.vshost.exe ExceptionManager.ThreadIdentity: ExceptionManager.WindowsIdentity: xxxxx 1) Exception Information Exception Type: Microsoft.Practices.Composite.Modularity.ModuleInitializeException ModuleName: AdminModule Message: An exception occurred while initializing module 'AdminModule'. - The exception message was: Activation error occured while trying to get instance of type AdminModule, key "" Check the InnerException property of the exception for more information. If the exception occurred while creating an object in a DI container, you can exception.GetRootException() to help locate the root cause of the problem. Data: System.Collections.ListDictionaryInternal TargetSite: Void HandleModuleInitializationError(Microsoft.Practices.Composite.Modularity.ModuleInfo, System.String, System.Exception) HelpLink: NULL Source: Microsoft.Practices.Composite StackTrace Information at Microsoft.Practices.Composite.Modularity.ModuleInitializer.HandleModuleInitializationError(ModuleInfo moduleInfo, String assemblyName, Exception exception) at Microsoft.Practices.Composite.Modularity.ModuleInitializer.Initialize(ModuleInfo moduleInfo) at Microsoft.Practices.Composite.Modularity.ModuleManager.InitializeModule(ModuleInfo moduleInfo) at Microsoft.Practices.Composite.Modularity.ModuleManager.LoadModulesThatAreReadyForLoad() at Microsoft.Practices.Composite.Modularity.ModuleManager.OnModuleTypeLoaded(ModuleInfo typeLoadedModuleInfo, Exception error) at Microsoft.Practices.Composite.Modularity.FileModuleTypeLoader.BeginLoadModuleType(ModuleInfo moduleInfo, ModuleTypeLoadedCallback callback) at Microsoft.Practices.Composite.Modularity.ModuleManager.BeginRetrievingModule(ModuleInfo moduleInfo) at Microsoft.Practices.Composite.Modularity.ModuleManager.LoadModuleTypes(IEnumerable`1 moduleInfos) at Microsoft.Practices.Composite.Modularity.ModuleManager.LoadModulesWhenAvailable() at Microsoft.Practices.Composite.Modularity.ModuleManager.Run() at Microsoft.Practices.Composite.UnityExtensions.UnityBootstrapper.InitializeModules() at Infinity.Bootstrapper.InitializeModules() in D:\Projects\dotNet\Infinity\source\Inifinty\Infinity\Application Modules\BootStrapper.cs:line 75 at Microsoft.Practices.Composite.UnityExtensions.UnityBootstrapper.Run(Boolean runWithDefaultConfiguration) at Microsoft.Practices.Composite.UnityExtensions.UnityBootstrapper.Run() at Infinity.App.Application_Startup(Object sender, StartupEventArgs e) in D:\Projects\dotNet\Infinity\source\Inifinty\Infinity\App.xaml.cs:line 37 at System.Windows.Application.OnStartup(StartupEventArgs e) at System.Windows.Application.<.ctorb__0(Object unused) at System.Windows.Threading.ExceptionWrapper.InternalRealCall(Delegate callback, Object args, Boolean isSingleParameter) at System.Windows.Threading.ExceptionWrapper.TryCatchWhen(Object source, Delegate callback, Object args, Boolean isSingleParameter, Delegate catchHandler) 2) Exception Information Exception Type: Microsoft.Practices.ServiceLocation.ActivationException Message: Activation error occured while trying to get instance of type AdminModule, key "" Data: System.Collections.ListDictionaryInternal TargetSite: System.Object GetInstance(System.Type, System.String) HelpLink: NULL Source: Microsoft.Practices.ServiceLocation StackTrace Information at Microsoft.Practices.ServiceLocation.ServiceLocatorImplBase.GetInstance(Type serviceType, String key) at Microsoft.Practices.ServiceLocation.ServiceLocatorImplBase.GetInstance(Type serviceType) at Microsoft.Practices.Composite.Modularity.ModuleInitializer.CreateModule(String typeName) at Microsoft.Practices.Composite.Modularity.ModuleInitializer.Initialize(ModuleInfo moduleInfo) 3) Exception Information Exception Type: Microsoft.Practices.Unity.ResolutionFailedException TypeRequested: AdminModule NameRequested: NULL Message: Resolution of the dependency failed, type = "Infinity.Modules.Admin.AdminModule", name = "". Exception message is: The current build operation (build key Build Key[Infinity.Modules.Admin.AdminModule, null]) failed: The parameter screenFactoryRegistry could not be resolved when attempting to call constructor Infinity.Modules.Admin.AdminModule(Microsoft.Practices.Unity.IUnityContainer container, PhoenixIT.IScreenFactoryRegistry screenFactoryRegistry, Microsoft.Practices.Composite.Events.IEventAggregator eventAggregator, PhoenixIT.IBusyService busyService). (Strategy type BuildPlanStrategy, index 3) Data: System.Collections.ListDictionaryInternal TargetSite: System.Object DoBuildUp(System.Type, System.Object, System.String) HelpLink: NULL Source: Microsoft.Practices.Unity StackTrace Information at Microsoft.Practices.Unity.UnityContainer.DoBuildUp(Type t, Object existing, String name) at Microsoft.Practices.Unity.UnityContainer.DoBuildUp(Type t, String name) at Microsoft.Practices.Unity.UnityContainer.Resolve(Type t, String name) at Microsoft.Practices.Composite.UnityExtensions.UnityServiceLocatorAdapter.DoGetInstance(Type serviceType, String key) at Microsoft.Practices.ServiceLocation.ServiceLocatorImplBase.GetInstance(Type serviceType, String key) 4) Exception Information Exception Type: Microsoft.Practices.ObjectBuilder2.BuildFailedException ExecutingStrategyTypeName: BuildPlanStrategy ExecutingStrategyIndex: 3 BuildKey: Build Key[Infinity.Modules.Admin.AdminModule, null] Message: The current build operation (build key Build Key[Infinity.Modules.Admin.AdminModule, null]) failed: The parameter screenFactoryRegistry could not be resolved when attempting to call constructor Infinity.Modules.Admin.AdminModule(Microsoft.Practices.Unity.IUnityContainer container, PhoenixIT.IScreenFactoryRegistry screenFactoryRegistry, Microsoft.Practices.Composite.Events.IEventAggregator eventAggregator, PhoenixIT.IBusyService busyService). (Strategy type BuildPlanStrategy, index 3) Data: System.Collections.ListDictionaryInternal TargetSite: System.Object ExecuteBuildUp(Microsoft.Practices.ObjectBuilder2.IBuilderContext) HelpLink: NULL Source: Microsoft.Practices.ObjectBuilder2 StackTrace Information at Microsoft.Practices.ObjectBuilder2.StrategyChain.ExecuteBuildUp(IBuilderContext context) at Microsoft.Practices.ObjectBuilder2.Builder.BuildUp(IReadWriteLocator locator, ILifetimeContainer lifetime, IPolicyList policies, IStrategyChain strategies, Object buildKey, Object existing) at Microsoft.Practices.Unity.UnityContainer.DoBuildUp(Type t, Object existing, String name) 5) Exception Information Exception Type: System.InvalidOperationException Message: The parameter screenFactoryRegistry could not be resolved when attempting to call constructor Infinity.Modules.Admin.AdminModule(Microsoft.Practices.Unity.IUnityContainer container, PhoenixIT.IScreenFactoryRegistry screenFactoryRegistry, Microsoft.Practices.Composite.Events.IEventAggregator eventAggregator, PhoenixIT.IBusyService busyService). Data: System.Collections.ListDictionaryInternal TargetSite: Void ThrowForResolutionFailed(System.Exception, System.String, System.String, Microsoft.Practices.ObjectBuilder2.IBuilderContext) HelpLink: NULL Source: Microsoft.Practices.ObjectBuilder2 StackTrace Information at Microsoft.Practices.ObjectBuilder2.DynamicMethodConstructorStrategy.ThrowForResolutionFailed(Exception inner, String parameterName, String constructorSignature, IBuilderContext context) at BuildUp_Infinity.Modules.Admin.AdminModule(IBuilderContext ) at Microsoft.Practices.ObjectBuilder2.DynamicMethodBuildPlan.BuildUp(IBuilderContext context) at Microsoft.Practices.ObjectBuilder2.BuildPlanStrategy.PreBuildUp(IBuilderContext context) at Microsoft.Practices.ObjectBuilder2.StrategyChain.ExecuteBuildUp(IBuilderContext context) 6) Exception Information Exception Type: Microsoft.Practices.ObjectBuilder2.BuildFailedException ExecutingStrategyTypeName: BuildPlanStrategy ExecutingStrategyIndex: 3 BuildKey: Build Key[PhoenixIT.IScreenFactoryRegistry, null] Message: The current build operation (build key Build Key[PhoenixIT.IScreenFactoryRegistry, null]) failed: The current type, PhoenixIT.IScreenFactoryRegistry, is an interface and cannot be constructed. Are you missing a type mapping? (Strategy type BuildPlanStrategy, index 3) Data: System.Collections.ListDictionaryInternal TargetSite: System.Object ExecuteBuildUp(Microsoft.Practices.ObjectBuilder2.IBuilderContext) HelpLink: NULL Source: Microsoft.Practices.ObjectBuilder2 StackTrace Information at Microsoft.Practices.ObjectBuilder2.StrategyChain.ExecuteBuildUp(IBuilderContext context) at Microsoft.Practices.Unity.ObjectBuilder.NamedTypeDependencyResolverPolicy.Resolve(IBuilderContext context) at BuildUp_Infinity.Modules.Admin.AdminModule(IBuilderContext ) 7) Exception Information Exception Type: System.InvalidOperationException Message: The current type, PhoenixIT.IScreenFactoryRegistry, is an interface and cannot be constructed. Are you missing a type mapping? Data: System.Collections.ListDictionaryInternal TargetSite: Void ThrowForAttemptingToConstructInterface(Microsoft.Practices.ObjectBuilder2.IBuilderContext) HelpLink: NULL Source: Microsoft.Practices.ObjectBuilder2 StackTrace Information at Microsoft.Practices.ObjectBuilder2.DynamicMethodConstructorStrategy.ThrowForAttemptingToConstructInterface(IBuilderContext context) at BuildUp_PhoenixIT.IScreenFactoryRegistry(IBuilderContext ) at Microsoft.Practices.ObjectBuilder2.DynamicMethodBuildPlan.BuildUp(IBuilderContext context) at Microsoft.Practices.ObjectBuilder2.BuildPlanStrategy.PreBuildUp(IBuilderContext context) at Microsoft.Practices.ObjectBuilder2.StrategyChain.ExecuteBuildUp(IBuilderContext context) For more information, see Help and Support Center at http://go.microsoft.com/fwlink/events.asp.

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  • HTML5 Input type=date Formatting Issues

    - by Rick Strahl
    One of the nice features in HTML5 is the abililty to specify a specific input type for HTML text input boxes. There a host of very useful input types available including email, number, date, datetime, month, number, range, search, tel, time, url and week. For a more complete list you can check out the MDN reference. Date input types also support automatic validation which can be useful in some scenarios but maybe can get in the way at other times. One of the more common input types, and one that can most benefit of a custom UI for selection is of course date input. Almost every application could use a decent date representation and HTML5's date input type seems to push into the right direction. It'd be nice if you could just say:<form action="DateTest.html"> <label for="FromDate">Enter a Date:</label> <input type="date" id="FromDate" name="FromDate" value="11/08/2012" class="date" /> <hr /> <input type="submit" id="btnSubmit" name="btnSubmit" value="Save Date" class="smallbutton" /> </form> but if you'd expect to just work, you're likely to be pretty disappointed. Problem #1: Browser Support For starters there's browser support. Out of the major browsers only the latest versions of WebKit and Opera based browsers seem to support date input. Neither FireFox, nor any version of Internet Explorer (including the new touch enabled IE10 in Windows RT) support input type=date. Browser support is an issue, but it would be OK if it wasn't for problem #2. Problem #2: Date Formatting If you look at my date input from before:<input type="date" id="FromDate" name="FromDate" value="11/08/2012" class="date" /> You can see that my date is formatted in local date format (ie. en-us). Now when I run this sadly the form that comes up in Chrome (and also iOS mobile browsers) comes up like this: Chrome isn't recognizing my local date string. Instead it's expecting my date format to be provided in ISO 8601 format which is: 2012-11-08 So if I change the date input field to:<input type="date" id="FromDate" name="FromDate" value="2012-10-08" class="date" /> I correctly get the date field filled in: Also when I pick a date with the DatePicker the date value is also returned is also set to the ISO date format. Yet notice how the date is still formatted to the local date time format (ie. en-US format). So if I pick a new date: and then save, the value field is set back to: 2012-11-15 using the ISO format. The same is true for Opera and iOS browsers and I suspect any other WebKit style browser and their date pickers. So to summarize input type=date: Expects ISO 8601 format dates to display intial values Sets selected date values to ISO 8601 Now what? This would sort of make sense, if all browsers supported input type=date. It'd be easy because you could just format dates appropriately when you set the date value into the control by applying the appropriate culture formatting (ie. .ToString("yyyy-MM-dd") ). .NET is actually smart enough to pick up the date on the other end for modelbinding when ISO 8601 is used. For other environments this might be a bit more tricky. input type=date is clearly the way to go forward. Date controls implemented in HTML are going the way of the dodo, given the intricacies of mobile platforms and scaling for both desktop and mobile. I've been using jQuery UI Datepicker for ages but once going to mobile, that's no longer an option as the control doesn't scale down well for mobile apps (at least not without major re-styling). It also makes a lot of sense for the browser to provide this functionality - creating a consistent date input experience across apps only makes sense, which is why I find it baffling that neither FireFox nor IE 10 deign it necessary to support date input natively. The problem is that a large number of even the latest and greatest browsers don't support this. So now you're stuck with not knowing what date format you have to serve since neither the local format, nor the ISO format works in all cases. For my current app I just broke down and used the ISO format and so I'll live with the non-local date format. <input type="date" id="ToDate" name="ToDate" value="2012-11-08" class="date"/> Here's what this looks like on Chrome: Here's what it looks like on my iPhone: Both Chrome and the phone do this the way it should be. For the phone especially this demonstrates why we'd want this - the built-in date picker there certainly beats manually trying to edit the date using finger gymnastics, and it's one of the easiest ways to pick a date I can think of (ie. easier to use than your typical date picker). Finally here's what the date looks like in FireFox: Certainly this is not the ideal date format, but it's clear enough I suppose. If users enter a date in local US format and that works as well (but won't work for other locales). It'll have to do. Over time one can only hope that other browsers will finally decide to implement this functionality natively to provide a unique experience. Until then, incomplete solutions it is. Related Posts Html 5 Input Types - How useful is this really going to be?© Rick Strahl, West Wind Technologies, 2005-2012Posted in HTML5  HTML   Tweet !function(d,s,id){var js,fjs=d.getElementsByTagName(s)[0];if(!d.getElementById(id)){js=d.createElement(s);js.id=id;js.src="//platform.twitter.com/widgets.js";fjs.parentNode.insertBefore(js,fjs);}}(document,"script","twitter-wjs"); (function() { var po = document.createElement('script'); po.type = 'text/javascript'; po.async = true; po.src = 'https://apis.google.com/js/plusone.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(po, s); })();

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  • Unable to cast transparent proxy to type &lt;type&gt;

    - by Rick Strahl
    This is not the first time I've run into this wonderful error while creating new AppDomains in .NET and then trying to load types and access them across App Domains. In almost all cases the problem I've run into with this error the problem comes from the two AppDomains involved loading different copies of the same type. Unless the types match exactly and come exactly from the same assembly the typecast will fail. The most common scenario is that the types are loaded from different assemblies - as unlikely as that sounds. An Example of Failure To give some context, I'm working on some old code in Html Help Builder that creates a new AppDomain in order to parse assembly information for documentation purposes. I create a new AppDomain in order to load up an assembly process it and then immediately unload it along with the AppDomain. The AppDomain allows for unloading that otherwise wouldn't be possible as well as isolating my code from the assembly that's being loaded. The process to accomplish this is fairly established and I use it for lots of applications that use add-in like functionality - basically anywhere where code needs to be isolated and have the ability to be unloaded. My pattern for this is: Create a new AppDomain Load a Factory Class into the AppDomain Use the Factory Class to load additional types from the remote domain Here's the relevant code from my TypeParserFactory that creates a domain and then loads a specific type - TypeParser - that is accessed cross-AppDomain in the parent domain:public class TypeParserFactory : System.MarshalByRefObject,IDisposable { …/// <summary> /// TypeParser Factory method that loads the TypeParser /// object into a new AppDomain so it can be unloaded. /// Creates AppDomain and creates type. /// </summary> /// <returns></returns> public TypeParser CreateTypeParser() { if (!CreateAppDomain(null)) return null; /// Create the instance inside of the new AppDomain /// Note: remote domain uses local EXE's AppBasePath!!! TypeParser parser = null; try { Assembly assembly = Assembly.GetExecutingAssembly(); string assemblyPath = Assembly.GetExecutingAssembly().Location; parser = (TypeParser) this.LocalAppDomain.CreateInstanceFrom(assemblyPath, typeof(TypeParser).FullName).Unwrap(); } catch (Exception ex) { this.ErrorMessage = ex.GetBaseException().Message; return null; } return parser; } private bool CreateAppDomain(string lcAppDomain) { if (lcAppDomain == null) lcAppDomain = "wwReflection" + Guid.NewGuid().ToString().GetHashCode().ToString("x"); AppDomainSetup setup = new AppDomainSetup(); // *** Point at current directory setup.ApplicationBase = AppDomain.CurrentDomain.BaseDirectory; //setup.PrivateBinPath = Path.Combine(AppDomain.CurrentDomain.BaseDirectory, "bin"); this.LocalAppDomain = AppDomain.CreateDomain(lcAppDomain,null,setup); // Need a custom resolver so we can load assembly from non current path AppDomain.CurrentDomain.AssemblyResolve += new ResolveEventHandler(CurrentDomain_AssemblyResolve); return true; } …} Note that the classes must be either [Serializable] (by value) or inherit from MarshalByRefObject in order to be accessible remotely. Here I need to call methods on the remote object so all classes are MarshalByRefObject. The specific problem code is the loading up a new type which points at an assembly that visible both in the current domain and the remote domain and then instantiates a type from it. This is the code in question:Assembly assembly = Assembly.GetExecutingAssembly(); string assemblyPath = Assembly.GetExecutingAssembly().Location; parser = (TypeParser) this.LocalAppDomain.CreateInstanceFrom(assemblyPath, typeof(TypeParser).FullName).Unwrap(); The last line of code is what blows up with the Unable to cast transparent proxy to type <type> error. Without the cast the code actually returns a TransparentProxy instance, but the cast is what blows up. In other words I AM in fact getting a TypeParser instance back but it can't be cast to the TypeParser type that is loaded in the current AppDomain. Finding the Problem To see what's going on I tried using the .NET 4.0 dynamic type on the result and lo and behold it worked with dynamic - the value returned is actually a TypeParser instance: Assembly assembly = Assembly.GetExecutingAssembly(); string assemblyPath = Assembly.GetExecutingAssembly().Location; object objparser = this.LocalAppDomain.CreateInstanceFrom(assemblyPath, typeof(TypeParser).FullName).Unwrap(); // dynamic works dynamic dynParser = objparser; string info = dynParser.GetVersionInfo(); // method call works // casting fails parser = (TypeParser)objparser; So clearly a TypeParser type is coming back, but nevertheless it's not the right one. Hmmm… mysterious.Another couple of tries reveal the problem however:// works dynamic dynParser = objparser; string info = dynParser.GetVersionInfo(); // method call works // c:\wwapps\wwhelp\wwReflection20.dll (Current Execution Folder) string info3 = typeof(TypeParser).Assembly.CodeBase; // c:\program files\vfp9\wwReflection20.dll (my COM client EXE's folder) string info4 = dynParser.GetType().Assembly.CodeBase; // fails parser = (TypeParser)objparser; As you can see the second value is coming from a totally different assembly. Note that this is even though I EXPLICITLY SPECIFIED an assembly path to load the assembly from! Instead .NET decided to load the assembly from the original ApplicationBase folder. Ouch! How I actually tracked this down was a little more tedious: I added a method like this to both the factory and the instance types and then compared notes:public string GetVersionInfo() { return ".NET Version: " + Environment.Version.ToString() + "\r\n" + "wwReflection Assembly: " + typeof(TypeParserFactory).Assembly.CodeBase.Replace("file:///", "").Replace("/", "\\") + "\r\n" + "Assembly Cur Dir: " + Directory.GetCurrentDirectory() + "\r\n" + "ApplicationBase: " + AppDomain.CurrentDomain.SetupInformation.ApplicationBase + "\r\n" + "App Domain: " + AppDomain.CurrentDomain.FriendlyName + "\r\n"; } For the factory I got: .NET Version: 4.0.30319.239wwReflection Assembly: c:\wwapps\wwhelp\bin\wwreflection20.dllAssembly Cur Dir: c:\wwapps\wwhelpApplicationBase: C:\Programs\vfp9\App Domain: wwReflection534cfa1f For the instance type I got: .NET Version: 4.0.30319.239wwReflection Assembly: C:\\Programs\\vfp9\wwreflection20.dllAssembly Cur Dir: c:\\wwapps\\wwhelpApplicationBase: C:\\Programs\\vfp9\App Domain: wwDotNetBridge_56006605 which clearly shows the problem. You can see that both are loading from different appDomains but the each is loading the assembly from a different location. Probably a better solution yet (for ANY kind of assembly loading problem) is to use the .NET Fusion Log Viewer to trace assembly loads.The Fusion viewer will show a load trace for each assembly loaded and where it's looking to find it. Here's what the viewer looks like: The last trace above that I found for the second wwReflection20 load (the one that is wonky) looks like this:*** Assembly Binder Log Entry (1/13/2012 @ 3:06:49 AM) *** The operation was successful. Bind result: hr = 0x0. The operation completed successfully. Assembly manager loaded from: C:\Windows\Microsoft.NET\Framework\V4.0.30319\clr.dll Running under executable c:\programs\vfp9\vfp9.exe --- A detailed error log follows. === Pre-bind state information === LOG: User = Ras\ricks LOG: DisplayName = wwReflection20, Version=4.61.0.0, Culture=neutral, PublicKeyToken=null (Fully-specified) LOG: Appbase = file:///C:/Programs/vfp9/ LOG: Initial PrivatePath = NULL LOG: Dynamic Base = NULL LOG: Cache Base = NULL LOG: AppName = vfp9.exe Calling assembly : (Unknown). === LOG: This bind starts in default load context. LOG: Using application configuration file: C:\Programs\vfp9\vfp9.exe.Config LOG: Using host configuration file: LOG: Using machine configuration file from C:\Windows\Microsoft.NET\Framework\V4.0.30319\config\machine.config. LOG: Policy not being applied to reference at this time (private, custom, partial, or location-based assembly bind). LOG: Attempting download of new URL file:///C:/Programs/vfp9/wwReflection20.DLL. LOG: Assembly download was successful. Attempting setup of file: C:\Programs\vfp9\wwReflection20.dll LOG: Entering run-from-source setup phase. LOG: Assembly Name is: wwReflection20, Version=4.61.0.0, Culture=neutral, PublicKeyToken=null LOG: Binding succeeds. Returns assembly from C:\Programs\vfp9\wwReflection20.dll. LOG: Assembly is loaded in default load context. WRN: The same assembly was loaded into multiple contexts of an application domain: WRN: Context: Default | Domain ID: 2 | Assembly Name: wwReflection20, Version=4.61.0.0, Culture=neutral, PublicKeyToken=null WRN: Context: LoadFrom | Domain ID: 2 | Assembly Name: wwReflection20, Version=4.61.0.0, Culture=neutral, PublicKeyToken=null WRN: This might lead to runtime failures. WRN: It is recommended to inspect your application on whether this is intentional or not. WRN: See whitepaper http://go.microsoft.com/fwlink/?LinkId=109270 for more information and common solutions to this issue. Notice that the fusion log clearly shows that the .NET loader makes no attempt to even load the assembly from the path I explicitly specified. Remember your Assembly Locations As mentioned earlier all failures I've seen like this ultimately resulted from different versions of the same type being available in the two AppDomains. At first sight that seems ridiculous - how could the types be different and why would you have multiple assemblies - but there are actually a number of scenarios where it's quite possible to have multiple copies of the same assembly floating around in multiple places. If you're hosting different environments (like hosting the Razor Engine, or ASP.NET Runtime for example) it's common to create a private BIN folder and it's important to make sure that there's no overlap of assemblies. In my case of Html Help Builder the problem started because I'm using COM interop to access the .NET assembly and the above code. COM Interop has very specific requirements on where assemblies can be found and because I was mucking around with the loader code today, I ended up moving assemblies around to a new location for explicit loading. The explicit load works in the main AppDomain, but failed in the remote domain as I showed. The solution here was simple enough: Delete the extraneous assembly which was left around by accident. Not a common problem, but one that when it bites is pretty nasty to figure out because it seems so unlikely that types wouldn't match. I know I've run into this a few times and writing this down hopefully will make me remember in the future rather than poking around again for an hour trying to debug the issue as I did today. Hopefully it'll save some of you some time as well in the future.© Rick Strahl, West Wind Technologies, 2005-2012Posted in .NET  COM   Tweet !function(d,s,id){var js,fjs=d.getElementsByTagName(s)[0];if(!d.getElementById(id)){js=d.createElement(s);js.id=id;js.src="//platform.twitter.com/widgets.js";fjs.parentNode.insertBefore(js,fjs);}}(document,"script","twitter-wjs"); (function() { var po = document.createElement('script'); po.type = 'text/javascript'; po.async = true; po.src = 'https://apis.google.com/js/plusone.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(po, s); })();

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  • C#/.NET Little Wonders: Constraining Generics with Where Clause

    - by James Michael Hare
    Back when I was primarily a C++ developer, I loved C++ templates.  The power of writing very reusable generic classes brought the art of programming to a brand new level.  Unfortunately, when .NET 1.0 came about, they didn’t have a template equivalent.  With .NET 2.0 however, we finally got generics, which once again let us spread our wings and program more generically in the world of .NET However, C# generics behave in some ways very differently from their C++ template cousins.  There is a handy clause, however, that helps you navigate these waters to make your generics more powerful. The Problem – C# Assumes Lowest Common Denominator In C++, you can create a template and do nearly anything syntactically possible on the template parameter, and C++ will not check if the method/fields/operations invoked are valid until you declare a realization of the type.  Let me illustrate with a C++ example: 1: // compiles fine, C++ makes no assumptions as to T 2: template <typename T> 3: class ReverseComparer 4: { 5: public: 6: int Compare(const T& lhs, const T& rhs) 7: { 8: return rhs.CompareTo(lhs); 9: } 10: }; Notice that we are invoking a method CompareTo() off of template type T.  Because we don’t know at this point what type T is, C++ makes no assumptions and there are no errors. C++ tends to take the path of not checking the template type usage until the method is actually invoked with a specific type, which differs from the behavior of C#: 1: // this will NOT compile! C# assumes lowest common denominator. 2: public class ReverseComparer<T> 3: { 4: public int Compare(T lhs, T rhs) 5: { 6: return lhs.CompareTo(rhs); 7: } 8: } So why does C# give us a compiler error even when we don’t yet know what type T is?  This is because C# took a different path in how they made generics.  Unless you specify otherwise, for the purposes of the code inside the generic method, T is basically treated like an object (notice I didn’t say T is an object). That means that any operations, fields, methods, properties, etc that you attempt to use of type T must be available at the lowest common denominator type: object.  Now, while object has the broadest applicability, it also has the fewest specific.  So how do we allow our generic type placeholder to do things more than just what object can do? Solution: Constraint the Type With Where Clause So how do we get around this in C#?  The answer is to constrain the generic type placeholder with the where clause.  Basically, the where clause allows you to specify additional constraints on what the actual type used to fill the generic type placeholder must support. You might think that narrowing the scope of a generic means a weaker generic.  In reality, though it limits the number of types that can be used with the generic, it also gives the generic more power to deal with those types.  In effect these constraints says that if the type meets the given constraint, you can perform the activities that pertain to that constraint with the generic placeholders. Constraining Generic Type to Interface or Superclass One of the handiest where clause constraints is the ability to specify the type generic type must implement a certain interface or be inherited from a certain base class. For example, you can’t call CompareTo() in our first C# generic without constraints, but if we constrain T to IComparable<T>, we can: 1: public class ReverseComparer<T> 2: where T : IComparable<T> 3: { 4: public int Compare(T lhs, T rhs) 5: { 6: return lhs.CompareTo(rhs); 7: } 8: } Now that we’ve constrained T to an implementation of IComparable<T>, this means that our variables of generic type T may now call any members specified in IComparable<T> as well.  This means that the call to CompareTo() is now legal. If you constrain your type, also, you will get compiler warnings if you attempt to use a type that doesn’t meet the constraint.  This is much better than the syntax error you would get within C++ template code itself when you used a type not supported by a C++ template. Constraining Generic Type to Only Reference Types Sometimes, you want to assign an instance of a generic type to null, but you can’t do this without constraints, because you have no guarantee that the type used to realize the generic is not a value type, where null is meaningless. Well, we can fix this by specifying the class constraint in the where clause.  By declaring that a generic type must be a class, we are saying that it is a reference type, and this allows us to assign null to instances of that type: 1: public static class ObjectExtensions 2: { 3: public static TOut Maybe<TIn, TOut>(this TIn value, Func<TIn, TOut> accessor) 4: where TOut : class 5: where TIn : class 6: { 7: return (value != null) ? accessor(value) : null; 8: } 9: } In the example above, we want to be able to access a property off of a reference, and if that reference is null, pass the null on down the line.  To do this, both the input type and the output type must be reference types (yes, nullable value types could also be considered applicable at a logical level, but there’s not a direct constraint for those). Constraining Generic Type to only Value Types Similarly to constraining a generic type to be a reference type, you can also constrain a generic type to be a value type.  To do this you use the struct constraint which specifies that the generic type must be a value type (primitive, struct, enum, etc). Consider the following method, that will convert anything that is IConvertible (int, double, string, etc) to the value type you specify, or null if the instance is null. 1: public static T? ConvertToNullable<T>(IConvertible value) 2: where T : struct 3: { 4: T? result = null; 5:  6: if (value != null) 7: { 8: result = (T)Convert.ChangeType(value, typeof(T)); 9: } 10:  11: return result; 12: } Because T was constrained to be a value type, we can use T? (System.Nullable<T>) where we could not do this if T was a reference type. Constraining Generic Type to Require Default Constructor You can also constrain a type to require existence of a default constructor.  Because by default C# doesn’t know what constructors a generic type placeholder does or does not have available, it can’t typically allow you to call one.  That said, if you give it the new() constraint, it will mean that the type used to realize the generic type must have a default (no argument) constructor. Let’s assume you have a generic adapter class that, given some mappings, will adapt an item from type TFrom to type TTo.  Because it must create a new instance of type TTo in the process, we need to specify that TTo has a default constructor: 1: // Given a set of Action<TFrom,TTo> mappings will map TFrom to TTo 2: public class Adapter<TFrom, TTo> : IEnumerable<Action<TFrom, TTo>> 3: where TTo : class, new() 4: { 5: // The list of translations from TFrom to TTo 6: public List<Action<TFrom, TTo>> Translations { get; private set; } 7:  8: // Construct with empty translation and reverse translation sets. 9: public Adapter() 10: { 11: // did this instead of auto-properties to allow simple use of initializers 12: Translations = new List<Action<TFrom, TTo>>(); 13: } 14:  15: // Add a translator to the collection, useful for initializer list 16: public void Add(Action<TFrom, TTo> translation) 17: { 18: Translations.Add(translation); 19: } 20:  21: // Add a translator that first checks a predicate to determine if the translation 22: // should be performed, then translates if the predicate returns true 23: public void Add(Predicate<TFrom> conditional, Action<TFrom, TTo> translation) 24: { 25: Translations.Add((from, to) => 26: { 27: if (conditional(from)) 28: { 29: translation(from, to); 30: } 31: }); 32: } 33:  34: // Translates an object forward from TFrom object to TTo object. 35: public TTo Adapt(TFrom sourceObject) 36: { 37: var resultObject = new TTo(); 38:  39: // Process each translation 40: Translations.ForEach(t => t(sourceObject, resultObject)); 41:  42: return resultObject; 43: } 44:  45: // Returns an enumerator that iterates through the collection. 46: public IEnumerator<Action<TFrom, TTo>> GetEnumerator() 47: { 48: return Translations.GetEnumerator(); 49: } 50:  51: // Returns an enumerator that iterates through a collection. 52: IEnumerator IEnumerable.GetEnumerator() 53: { 54: return GetEnumerator(); 55: } 56: } Notice, however, you can’t specify any other constructor, you can only specify that the type has a default (no argument) constructor. Summary The where clause is an excellent tool that gives your .NET generics even more power to perform tasks higher than just the base "object level" behavior.  There are a few things you cannot specify with constraints (currently) though: Cannot specify the generic type must be an enum. Cannot specify the generic type must have a certain property or method without specifying a base class or interface – that is, you can’t say that the generic must have a Start() method. Cannot specify that the generic type allows arithmetic operations. Cannot specify that the generic type requires a specific non-default constructor. In addition, you cannot overload a template definition with different, opposing constraints.  For example you can’t define a Adapter<T> where T : struct and Adapter<T> where T : class.  Hopefully, in the future we will get some of these things to make the where clause even more useful, but until then what we have is extremely valuable in making our generics more user friendly and more powerful!   Technorati Tags: C#,.NET,Little Wonders,BlackRabbitCoder,where,generics

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  • These are few objective type questions which i was not able to find the solution [closed]

    - by Tarun
    1. Which of the following advantages does System.Collections.IDictionaryEnumerator provide over System.Collections.IEnumerator? a. It adds properties for direct access to both the Key and the Value b. It is optimized to handle the structure of a Dictionary. c. It provides properties to determine if the Dictionary is enumerated in Key or Value order d. It provides reverse lookup methods to distinguish a Key from a specific Value 2. When Implementing System.EnterpriseServices.ServicedComponent derived classes, which of the following statements are true? a. Enabling object pooling requires an attribute on the class and the enabling of pooling in the COM+ catalog. b. Methods can be configured to automatically mark a transaction as complete by the use of attributes. c. You can configure authentication using the AuthenticationOption when the ActivationMode is set to Library. d. You can control the lifecycle policy of an individual instance using the SetLifetimeService method. 3. Which of the following are true regarding event declaration in the code below? class Sample { event MyEventHandlerType MyEvent; } a. MyEventHandlerType must be derived from System.EventHandler or System.EventHandler<TEventArgs> b. MyEventHandlerType must take two parameters, the first of the type Object, and the second of a class derived from System.EventArgs c. MyEventHandlerType may have a non-void return type d. If MyEventHandlerType is a generic type, event declaration must use a specialization of that type. e. MyEventHandlerType cannot be declared static 4. Which of the following statements apply to developing .NET code, using .NET utilities that are available with the SDK or Visual Studio? a. Developers can create assemblies directly from the MSIL Source Code. b. Developers can examine PE header information in an assembly. c. Developers can generate XML Schemas from class definitions contained within an assembly. d. Developers can strip all meta-data from managed assemblies. e. Developers can split an assembly into multiple assemblies. 5. Which of the following characteristics do classes in the System.Drawing namespace such as Brush,Font,Pen, and Icon share? a. They encapsulate native resource and must be properly Disposed to prevent potential exhausting of resources. b. They are all MarshalByRef derived classes, but functionality across AppDomains has specific limitations. c. You can inherit from these classes to provide enhanced or customized functionality 6. Which of the following are required to be true by objects which are going to be used as keys in a System.Collections.HashTable? a. They must handle case-sensitivity identically in both the GetHashCode() and Equals() methods. b. Key objects must be immutable for the duration they are used within a HashTable. c. Get HashCode() must be overridden to provide the same result, given the same parameters, regardless of reference equalityl unless the HashTable constructor is provided with an IEqualityComparer parameter. d. Each Element in a HashTable is stored as a Key/Value pair of the type System.Collections.DictionaryElement e. All of the above 7. Which of the following are true about Nullable types? a. A Nullable type is a reference type. b. A Nullable type is a structure. c. An implicit conversion exists from any non-nullable value type to a nullable form of that type. d. An implicit conversion exists from any nullable value type to a non-nullable form of that type. e. A predefined conversion from the nullable type S? to the nullable type T? exists if there is a predefined conversion from the non-nullable type S to the non-nullable type T 8. When using an automatic property, which of the following statements is true? a. The compiler generates a backing field that is completely inaccessible from the application code. b. The compiler generates a backing field that is a private instance member with a leading underscore that can be programmatically referenced. c. The compiler generates a backing field that is accessible via reflection d. The compiler generates a code that will store the information separately from the instance to ensure its security. 9. Which of the following does using Initializer Syntax with a collection as shown below require? CollectionClass numbers = new CollectionClass { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 }; a. The Collection Class must implement System.Collections.Generic.ICollection<T> b. The Collection Class must implement System.Collections.Generic.IList<T> c. Each of the Items in the Initializer List will be passed to the Add<T>(T item) method d. The items in the initializer will be treated as an IEnumerable<T> and passed to the collection constructor+K110 10. What impact will using implicitly typed local variables as in the following example have? var sample = "Hello World"; a. The actual type is determined at compilation time, and has no impact on the runtime b. The actual type is determined at runtime, and late binding takes effect c. The actual type is based on the native VARIANT concept, and no binding to a specific type takes place. d. "var" itself is a specific type defined by the framework, and no special binding takes place 11. Which of the following is not supported by remoting object types? a. well-known singleton b. well-known single call c. client activated d. context-agile 12. In which of the following ways do structs differ from classes? a. Structs can not implement interfaces b. Structs cannot inherit from a base struct c. Structs cannot have events interfaces d. Structs cannot have virtual methods 13. Which of the following is not an unboxing conversion? a. void Sample1(object o) { int i = (int)o; } b. void Sample1(ValueType vt) { int i = (int)vt; } c. enum E { Hello, World} void Sample1(System.Enum et) { E e = (E) et; } d. interface I { int Value { get; set; } } void Sample1(I vt) { int i = vt.Value; } e. class C { public int Value { get; set; } } void Sample1(C vt) { int i = vt.Value; } 14. Which of the following are characteristics of the System.Threading.Timer class? a. The method provided by the TimerCallback delegate will always be invoked on the thread which created the timer. b. The thread which creates the timer must have a message processing loop (i.e. be considered a UI thread) c. The class contains protection to prevent reentrancy to the method provided by the TimerCallback delegate d. You can receive notification of an instance being Disposed by calling an overload of the Dispose method. 15. What is the proper declaration of a method which will handle the following event? Class MyClass { public event EventHandler MyEvent; } a. public void A_MyEvent(object sender, MyArgs e) { } b. public void A_MyEvent(object sender, EventArgs e) { } c. public void A_MyEvent(MyArgs e) { } d. public void A_MyEvent(MyClass sender,EventArgs e) { } 16. Which of the following scenarios are applicable to Window Workflow Foundation? a. Document-centric workflows b. Human workflows c. User-interface page flows d. Builtin support for communications across multiple applications and/or platforms e. All of the above 17. When using an automatic property, which of the following statements is true? a. The compiler generates a backing field that is completely inaccessible from the application code. b. The compiler generates a backing field that is a private instance member with a leading underscore that can be programmatically referenced. c. The compiler generates a backing field that is accessible via reflection d. The compiler generates a code that will store the information separately from the instance to ensure its security. 18 While using the capabilities supplied by the System.Messaging classes, which of the following are true? a. Information must be explicitly converted to/from a byte stream before it uses the MessageQueue class b. Invoking the MessageQueue.Send member defaults to using the System.Messaging.XmlMessageFormatter to serialize the object. c. Objects must be XMLSerializable in order to be transferred over a MessageQueue instance. d. The first entry in a MessageQueue must be removed from the queue before the next entry can be accessed e. Entries removed from a MessageQueue within the scope of a transaction, will be pushed back into the front of the queue if the transaction fails. 19. Which of the following are true about declarative attributes? a. They must be inherited from the System.Attribute. b. Attributes are instantiated at the same time as instances of the class to which they are applied. c. Attribute classes may be restricted to be applied only to application element types. d. By default, a given attribute may be applied multiple times to the same application element. 20. When using version 3.5 of the framework in applications which emit a dynamic code, which of the following are true? a. A Partial trust code can not emit and execute a code b. A Partial trust application must have the SecurityCriticalAttribute attribute have called Assert ReflectionEmit permission c. The generated code no more permissions than the assembly which emitted it. d. It can be executed by calling System.Reflection.Emit.DynamicMethod( string name, Type returnType, Type[] parameterTypes ) without any special permissions Within Windows Workflow Foundation, Compensating Actions are used for: a. provide a means to rollback a failed transaction b. provide a means to undo a successfully committed transaction later c. provide a means to terminate an in process transaction d. achieve load balancing by adapting to the current activity 21. What is the proper declaration of a method which will handle the following event? Class MyClass { public event EventHandler MyEvent; } a. public void A_MyEvent(object sender, MyArgs e) { } b. public void A_MyEvent(object sender, EventArgs e) { } c. public void A_MyEvent(MyArgs e) { } d. public void A_MyEvent(MyClass sender,EventArgs e) { } 22. Which of the following controls allows the use of XSL to transform XML content into formatted content? a. System.Web.UI.WebControls.Xml b. System.Web.UI.WebControls.Xslt c. System.Web.UI.WebControls.Substitution d. System.Web.UI.WebControls.Transform 23. To which of the following do automatic properties refer? a. You declare (explicitly or implicitly) the accessibility of the property and get and set accessors, but do not provide any implementation or backing field b. You attribute a member field so that the compiler will generate get and set accessors c. The compiler creates properties for your class based on class level attributes d. They are properties which are automatically invoked as part of the object construction process 24. Which of the following are true about Nullable types? a. A Nullable type is a reference type. b. An implicit conversion exists from any non-nullable value type to a nullable form of that type. c. A predefined conversion from the nullable type S? to the nullable type T? exists if there is a predefined conversion from the non-nullable type S to the non-nullable type T 25. When using an automatic property, which of the following statements is true? a. The compiler generates a backing field that is completely inaccessible from the application code. b. The compiler generates a backing field that is accessible via reflection. c. The compiler generates a code that will store the information separately from the instance to ensure its security. 26. When using an implicitly typed array, which of the following is most appropriate? a. All elements in the initializer list must be of the same type. b. All elements in the initializer list must be implicitly convertible to a known type which is the actual type of at least one member in the initializer list c. All elements in the initializer list must be implicitly convertible to common type which is a base type of the items actually in the list 27. Which of the following is false about anonymous types? a. They can be derived from any reference type. b. Two anonymous types with the same named parameters in the same order declared in different classes have the same type. c. All properties of an anonymous type are read/write. 28. Which of the following are true about Extension methods. a. They can be declared either static or instance members b. They must be declared in the same assembly (but may be in different source files) c. Extension methods can be used to override existing instance methods d. Extension methods with the same signature for the same class may be declared in multiple namespaces without causing compilation errors

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  • Parameter _rollback_segment_count can cause trouble

    - by Mike Dietrich
    Just some weeks ago we've learned that setting the hidden underscore parameter: _rollback_segment_count may cause trouble during upgrade. This parameter is used in very rare cases to have under all circumstances and situations this specified number of UNDO's online. Now during upgrade this may result in massive latch contention due to bug14226559 - and there's a patch available as well. Recommendation is to unset it during upgrade. I don't think that many people will hit this as I personally haven't seen databases with this underscore in their init.ora or spfiles. So take this post more or less as a reminder for myself

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  • Entity Framework 4.0: Creating objects of correct type when using lazy loading

    - by DigiMortal
    In my posting about Entity Framework 4.0 and POCOs I introduced lazy loading in EF applications. EF uses proxy classes for lazy loading and this means we have new types in that come and go dynamically in runtime. We don’t have these types available when we write code but we cannot forget that EF may expect us to use dynamically generated types. In this posting I will give you simple hint how to use correct types in your code. The background of lazy loading and proxy classes As a first thing I will explain you in short what is proxy class. Business classes when designed correctly have no knowledge about their birth and death – they don’t know how they are created and they don’t know how their data is persisted. This is the responsibility of object runtime. When we use lazy loading we need a little bit different classes that know how to load data for properties when code accesses the property first time. As we cannot add this functionality to our business classes (they may be stored through more than one data access technology or by more than one Data Access Layer (DAL)) we create proxy classes that extend our business classes. If we have class called Product and product has lazy loaded property called Customer then we need proxy class, let’s say ProductProxy, that has same public signature as Product so we can use it INSTEAD OF product in our code. ProductProxy overrides Customer property. If customer is not asked then customer is null. But if we ask for Customer property then overridden property of ProductProxy loads it from database. This is how lazy loading works. Problem – two types for same thing As lazy loading may introduce dynamically generated proxy types we don’t know in our application code which type is returned. We cannot be sure that we have Product not ProductProxy returned. This leads us to the following question: how can we create Product of correct type if we don’t know the correct type? In EF solution is simple. Solution – use factory methods If you are using repositories and you are not using factories (imho it is pretty pointless with mapper) you can add factory methods to your EF based repositories. Take a look at this class. public class Event {     public int ID { get; set; }     public string Title { get; set; }     public string Location { get; set; }     public virtual Party Organizer { get; set; }     public DateTime Date { get; set; } } We have virtual member called Organizer. This property is virtual because we want to use lazy loading on this class so Organizer is loaded only when we ask it. EF provides us with method called CreateObject<T>(). CreateObject<T>() is member of ObjectContext class and it creates the object based on given type. In runtime proxy type for Event is created for us automatically and when we call CreateObject<T>() for Event it returns as object of Event proxy type. The factory method for events repository is as follows. public Event CreateEvent() {     var evt = _context.CreateObject<Event>();     return evt; } And we are done. Instead of creating factory classes we created factory methods that guarantee that created objects are of correct type. Conclusion Although lazy loading introduces some new objects we cannot use at design time because they live only in runtime we can write code without worrying about exact implementation type of object. This holds true until we have clean code and we don’t make any decisions based on object type. EF4.0 provides us with very simple factory method that create and return objects of correct type. All we had to do was adding factory methods to our repositories.

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  • ASP.NET Create zip file for download: the compressed zipped folder is invalid or corrupted

    - by Jason Braswell
    string fileName = "test.zip"; string path = "c:\\temp\\"; string fullPath = path + fileName; FileInfo file = new FileInfo(fullPath); Response.Clear(); Response.ClearContent(); Response.ClearHeaders(); Response.Buffer = true; Response.AppendHeader("content-disposition", "attachment; filename=" + fileName ); Response.AppendHeader("content-length", file.Length.ToString()); Response.ContentType = "application/x-compressed"; Response.TransmitFile(fullPath); Response.Flush(); Response.End(); The actual zip file c:\temp\test.zip is good, valid, whatever you want to call it. When I navigate to the directory c:\temp\ and double-click on the test.zip file; it opens right up. My problem seems only to be with the download. The code above executes without any issue. A file download dialog is presented. I can chose to either save or open. If I try to open the file from the dialog, or save it and then open it. I get the following dialog message: The Compressed (zipped) Folder is invalid or corrupted. For Response.ContentType I've tried: application/x-compressed application/x-zip-compressed application/x-gzip-compresse application/octet-stream application/zip The zip file is being created with some prior code (that I'm sure is working fine due to my ability to open the created file directly) using: Ionic.zip http://www.codeplex.com/DotNetZip

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  • Question about Target parameter of Matrix.CreateLookAt

    - by manning18
    I have a newbie question that's causing me a little bit of confusion when experimenting with cameras and reading other peoples implementations - does this parameter represent a point or a vector? In some examples I've seen people treat it like a specific point they are looking at (eg a position in the world), other times I see people caching the orientation of the camera in a rotation matrix and simply using the Matrix.Forward property as the "target", and other times it's a vector that's the result of targetPos - camPos and also I saw a camPos + orientation.Forward I was also just playing around with hard-coded target positions with same direction eg 1 to 10000 with no discernible difference in what I saw in the scene. Is the "Target" parameter actually a position or a direction (irrespective of magnitude)? Are there any subtle differences in behaviors, common mistakes or gotchas that are associated with what values you provide, or HOW you provide this paramter? Are all the methods I mentioned above equivalent? (sorry, I've only recently started and my math is still catching up)

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  • Sending a android.content.Context parameter to a function with JNI

    - by Ef Es
    I am trying to create a method that checks for internet connection that needs a Context parameter. The JNIHelper allows me to call static functions with parameters, but I don't know how to "retrieve" Cocos2d-x Activity class to use it as a parameter. public static boolean isNetworkAvailable(Context context) { boolean haveConnectedWifi = false; boolean haveConnectedMobile = false; ConnectivityManager cm = (ConnectivityManager) context.getSystemService( Context.CONNECTIVITY_SERVICE); NetworkInfo[] netInfo = cm.getAllNetworkInfo(); for (NetworkInfo ni : netInfo) { if (ni.getTypeName().equalsIgnoreCase("WIFI")) if (ni.isConnected()) haveConnectedWifi = true; if (ni.getTypeName().equalsIgnoreCase("MOBILE")) if (ni.isConnected()) haveConnectedMobile = true; } return haveConnectedWifi || haveConnectedMobile; } and the c++ code is JniMethodInfo methodInfo; if ( !JniHelper::getStaticMethodInfo( methodInfo, "my/app/TestApp", "isNetworkAvailable", "(android/content/Context;)V")) { //error return; } CCLog( "Method found and loaded!"); methodInfo.env->CallStaticVoidMethod( methodInfo.classID, methodInfo.methodID); methodInfo.env->DeleteLocalRef( methodInfo.classID);

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  • Simplifying C++11 optimal parameter passing when a copy is needed

    - by Mr.C64
    It seems to me that in C++11 lots of attention was made to simplify returning values from functions and methods, i.e.: with move semantics it's possible to simply return heavy-to-copy but cheap-to-move values (while in C++98/03 the general guideline was to use output parameters via non-const references or pointers), e.g.: // C++11 style vector<string> MakeAVeryBigStringList(); // C++98/03 style void MakeAVeryBigStringList(vector<string>& result); On the other side, it seems to me that more work should be done on input parameter passing, in particular when a copy of an input parameter is needed, e.g. in constructors and setters. My understanding is that the best technique in this case is to use templates and std::forward<>, e.g. (following the pattern of this answer on C++11 optimal parameter passing): class Person { std::string m_name; public: template <class T, class = typename std::enable_if < std::is_constructible<std::string, T>::value >::type> explicit Person(T&& name) : m_name(std::forward<T>(name)) { } ... }; A similar code could be written for setters. Frankly, this code seems boilerplate and complex, and doesn't scale up well when there are more parameters (e.g. if a surname attribute is added to the above class). Would it be possible to add a new feature to C++11 to simplify code like this (just like lambdas simplify C++98/03 code with functors in several cases)? I was thinking of a syntax with some special character, like @ (since introducing a &&& in addition to && would be too much typing :) e.g.: class Person { std::string m_name; public: /* Simplified syntax to produce boilerplate code like this: template <class T, class = typename std::enable_if < std::is_constructible<std::string, T>::value >::type> */ explicit Person(std::string@ name) : m_name(name) // implicit std::forward as well { } ... }; This would be very convenient also for more complex cases involving more parameters, e.g. Person(std::string@ name, std::string@ surname) : m_name(name), m_surname(surname) { } Would it be possible to add a simplified convenient syntax like this in C++? What would be the downsides of such a syntax?

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  • How to convert a gi-normous integer (in string format) to hex format? (C#)

    - by eviljack
    Given a potentially huge integer value (in c# string format), I want to be able to generate it's hex equivalent. Normal methods don't apply here as we are talking arbitrarily large numbers, 50 digits or more. The techniques I've seen which use a technique like this: // Store integer 182 int decValue = 182; // Convert integer 182 as a hex in a string variable string hexValue = decValue.ToString("X"); // Convert the hex string back to the number int decAgain = int.Parse(hexValue, System.Globalization.NumberStyles.HexNumber); won't work because the integer to convert is too large. For example I need to be able to convert a string like this: 843370923007003347112437570992242323 to it's hex equivalent. these don't work: http://stackoverflow.com/questions/1139957/c-convert-int-to-hex-and-back-again http://stackoverflow.com/questions/74148/how-to-convert-numbers-between-hex-and-decimal-in-c

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  • Getting the keyword as a parameter from Adwords using ValueTrack

    - by Stephen Ostermiller
    I set up an AdWords campaign for website following the instructions for Google AdWords ValueTrack. One of the things that it is supposed to be able to do is pass the keyword as a URL parameter using the code {keyword} in the URL. I set it up for integration with Google Analytics such the landing URLs would look like: http://example.com/landing.html?utm_source=adwords&utm_medium=cpc&utm_term=%7Bkeyword%7D&utm_content=my_content&utm_campaign=my_page where {keyword} is in the utm_term parameter. Hower, this keyword substitution isn't happening. Why?

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