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• Navigation in a #WP7 application with MVVM Light

  - by Laurent Bugnion

  In MVVM applications, it can be a bit of a challenge to send instructions to the view (for example a page) from a viewmodel. Thankfully, we have good tools at our disposal to help with that. In his excellent series “MVVM Light Toolkit soup to nuts”, Jesse Liberty proposes one approach using the MVVM Light messaging infrastructure. While this works fine, I would like to show here another approach using what I call a “view service”, i.e. an abstracted service that is invoked from the viewmodel, and implemented on the view. Multiple kinds of view services In fact, I use view services quite often, and even started standardizing them for the Windows Phone 7 applications I work on. If there is interest, I will be happy to show other such view services, for example Animation services, responsible to start/stop animations on the view. Dialog service, in charge of displaying messages to the user and gathering feedback. Navigation service, in charge of navigating to a given page directly from the viewmodel. In this article, I will concentrate on the navigation service. The INavigationService interface In most WP7 apps, the navigation service is used in quite a straightforward way. We want to: Navigate to a given URI. Go back. Be notified when a navigation is taking place, and be able to cancel. The INavigationService interface is quite simple indeed: public interface INavigationService { event NavigatingCancelEventHandler Navigating; void NavigateTo(Uri pageUri); void GoBack(); } Obviously, this interface can be extended if necessary, but in most of the apps I worked on, I found that this covers my needs. The NavigationService class It is possible to nicely pack the navigation service into its own class. To do this, we need to remember that all the PhoneApplicationPage instances use the same instance of the navigation service, exposed through their NavigationService property. In fact, in a WP7 application, it is the main frame (RootFrame, of type PhoneApplicationFrame) that is responsible for this task. So, our implementation of the NavigationService class can leverage this. First the class will grab the PhoneApplicationFrame and store a reference to it. Also, it registers a handler for the Navigating event, and forwards the event to the listening viewmodels (if any). Then, the NavigateTo and the GoBack methods are implemented. They are quite simple, because they are in fact just a gateway to the PhoneApplicationFrame. The whole class is as follows: public class NavigationService : INavigationService { private PhoneApplicationFrame _mainFrame; public event NavigatingCancelEventHandler Navigating; public void NavigateTo(Uri pageUri) { if (EnsureMainFrame()) { _mainFrame.Navigate(pageUri); } } public void GoBack() { if (EnsureMainFrame() && _mainFrame.CanGoBack) { _mainFrame.GoBack(); } } private bool EnsureMainFrame() { if (_mainFrame != null) { return true; } _mainFrame = Application.Current.RootVisual as PhoneApplicationFrame; if (_mainFrame != null) { // Could be null if the app runs inside a design tool _mainFrame.Navigating += (s, e) => { if (Navigating != null) { Navigating(s, e); } }; return true; } return false; } } Exposing URIs I find that it is a good practice to expose each page’s URI as a constant. In MVVM Light applications, a good place to do that is the ViewModelLocator, which already acts like a central point of setup for the views and their viewmodels. Note that in some cases, it is necessary to expose the URL as a string, for instance when a query string needs to be passed to the view. So for example we could have: public static readonly Uri MainPageUri = new Uri("/MainPage.xaml", UriKind.Relative); public const string AnotherPageUrl = "/AnotherPage.xaml?param1={0}&param2={1}"; Creating and using the NavigationService Normally, we only need one instance of the NavigationService class. In cases where you use an IOC container, it is easy to simply register a singleton instance. For example, I am using a modified version of a super simple IOC container, and so I can register the navigation service as follows: SimpleIoc.Register<INavigationService, NavigationService>(); Then, it can be resolved where needed with: SimpleIoc.Resolve<INavigationService>(); Or (more frequently), I simply declare a parameter on the viewmodel constructor of type INavigationService and let the IOC container do its magic and inject the instance of the NavigationService when the viewmodel is created. On supported platforms (for example Silverlight 4), it is also possible to use MEF. Or, of course, we can simply instantiate the NavigationService in the ViewModelLocator, and pass this instance as a parameter of the viewmodels’ constructor, injected as a property, etc… Once the instance has been passed to the viewmodel, it can be used, for example with: NavigationService.NavigateTo(ViewModelLocator.ComparisonPageUri); Testing Thanks to the INavigationService interface, navigation can be mocked and tested when the viewmodel is put under unit test. Simply implement and inject a mock class, and assert that the methods are called as they should by the viewmodel. Conclusion As usual, there are multiple ways to code a solution answering your needs. I find that view services are a really neat way to delegate view-specific responsibilities such as animation, dialogs and of course navigation to other classes through an abstracted interface. In some cases, such as the NavigationService class exposed here, it is even possible to standardize the implementation and pack it in a class library for reuse. I hope that this sample is useful! Happy coding. Laurent   Laurent Bugnion (GalaSoft) Subscribe | Twitter | Facebook | Flickr | LinkedIn

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• Django: way to test what class a generic relation content_object is?

  - by bitbutter

  In my project I have a class, NewsItem. Instances of NewsItem act like a wrapper. They can be associated with either an ArtWork instance, or an Announcement instance. Here's how the NewsItem model looks: class NewsItem(models.Model): content_type = models.ForeignKey(ContentType) object_id = models.PositiveIntegerField() content_object = generic.GenericForeignKey('content_type', 'object_id') date = models.DateTimeField(default=datetime.datetime.now,) class Meta: ordering = ('-date',) def __unicode__(self): return (self.title()) In a template I'm dealing with a NewsItem instance, and would like to output a certain bunch of html it it's 'wrapping' an Artwork instance, and a different bunch of html if it's wrapping an Announcement instance. Could someone explain how I can write a conditional to test for this? My first naive try looked like this: {% if news_item.content_object.type=='Artwork' %}do this{% else %}do that{% endif %}

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• How can I simulate the effects of an observable collection in this situation?

  - by MGSoto

  I am making a configuration editor for another application and am using reflection to pull editable fields from the configuration class. The following class is the base class for my various "DataTypeViewModels" and shows how I get and set the appropriate properties. public abstract class DataTypeViewModel<T> : ViewModelBase { Func<T> getFunction; Action<T> setAction; public const string ValuePropertyName = "Value"; public string Label { get; set; } public T Value { get { return getFunction.Invoke(); } set { if (getFunction.Invoke().Equals(value)) { return; } setAction.Invoke(value); // Update bindings, no broadcast RaisePropertyChanged(ValuePropertyName); } } /// <summary> /// Initializes a new instance of the StringViewModel class. /// </summary> public DataTypeViewModel(string sectionName, string label) { if (IsInDesignMode) { // Code runs in Blend --> create design time data. } else { Label = label; getFunction = new Func<T>(() => { return (T)Settings.Instance.GetType().GetProperty(sectionName).PropertyType. GetProperty(label).GetValue(Settings.Instance.GetType().GetProperty(sectionName).GetValue(Settings.Instance, null), null); }); setAction = new Action<T>(value => { Settings.Instance.GetType().GetProperty(sectionName).PropertyType.GetProperty(label). SetValue(Settings.Instance.GetType().GetProperty(sectionName).GetValue(Settings.Instance, null), value, null); }); } } } This part works the way I want it to, the next part is a sample DataTypeViewModel on a list of strings. public class StringListViewModel : DataTypeViewModel<ICollection<string>> { /// <summary> /// The <see cref="RemoveItemCommand" /> property's name. /// </summary> public const string RemoveItemCommandPropertyName = "RemoveItemCommand"; private RelayCommand<string> _removeItemCommand = null; public ObservableCollection<string> ObservableValue { get; set; } /// <summary> /// Gets the RemoveItemCommand property. /// TODO Update documentation: /// Changes to that property's value raise the PropertyChanged event. /// This property's value is broadcasted by the Messenger's default instance when it changes. /// </summary> public RelayCommand<string> RemoveItemCommand { get { return _removeItemCommand; } set { if (_removeItemCommand == value) { return; } var oldValue = _removeItemCommand; _removeItemCommand = value; // Update bindings, no broadcast RaisePropertyChanged(RemoveItemCommandPropertyName); } } /// <summary> /// The <see cref="AddItemCommand" /> property's name. /// </summary> public const string AddItemCommandPropertyName = "AddItemCommand"; private RelayCommand<string> _addItemCommand = null; /// <summary> /// Gets the AddItemCommand property. /// TODO Update documentation: /// Changes to that property's value raise the PropertyChanged event. /// This property's value is broadcasted by the Messenger's default instance when it changes. /// </summary> public RelayCommand<string> AddItemCommand { get { return _addItemCommand; } set { if (_addItemCommand == value) { return; } var oldValue = _addItemCommand; _addItemCommand = value; // Update bindings, no broadcast RaisePropertyChanged(AddItemCommandPropertyName); } } /// <summary> /// Initializes a new instance of the StringListViewModel class. /// </summary> public StringListViewModel(string sectionName, string label) : base(sectionName, label) { ObservableValue = new ObservableCollection<string>(Value); AddItemCommand = new RelayCommand<string>(param => { if (param != string.Empty) { Value.Add(param); ObservableValue.Add(param); } }); RemoveItemCommand = new RelayCommand<string>(param => { if (param != null) { Value.Remove(param); ObservableValue.Remove(param); } }); } } As you can see in the constructor, I currently have "Value" mirrored into a new ObservableCollection called "ObservableValue", which is then bound to by a ListView in the XAML. It works well this way, but cloning the List seems like such a hacky way to do this. While bound to Value, I've tried adding: RaisePropertyChanged("Value"); to the AddItemCommand and RemoveItemCommand, but this doesn't work, the ListView won't get updated. What is the proper way to do this?

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• Haskell: variant of `show` that doesn't wrap String and Char in quotes

  - by Joey Adams

  I'd like a variant of show (let's call it label) that acts just like show, except that it doesn't wrap Strings in " " or Chars in ' '. Examples: > label 5 "5" > label "hello" "hello" > label 'c' "c" I tried implementing this manually, but I ran into some walls. Here is what I tried: {-# LANGUAGE FlexibleInstances #-} {-# LANGUAGE UndecidableInstances #-} module Label where class (Show a) => Label a where label :: a -> String instance Label [Char] where label str = str instance Label Char where label c = [c] -- Default case instance Show a => Label a where label x = show x However, because the default case's class overlaps instance Label [Char] and instance Label Char, those types don't work with the label function. Is there a library function that provides this functionality? If not, is there a workaround to get the above code to work?

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• What comes first in Ruby's object model?

  - by Timothy

  I've been reading Metaprogramming Ruby and the object model like the chicken or egg dilemma. In Ruby 1.8, the Object class is an instance of Class. Module's superclass is Object and is an instance of Class. Class' superclass is Module, and it is an instance of Class (self-referential). Say class SomeClass; end is defined somewhere; SomeClass is an instance of Class, however its superclass is Object. Why does an instance of Class have Object as the superclass instead of nil? Also, if Object is to exist, then Class has to exist, but then Module has to exist, but for Module to exist Object has to exist. How are these classes created?

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• Override Django inlineformset_factory has_changed() to always return True

  - by John

  Hi, I am using the django inlineformset_factory function. a = get_object_or_404(ModelA, pk=id) FormSet = inlineformset_factory(ModelA, ModelB) if request.method == 'POST': metaform = FormSet (instance=a, data=request.POST) if metaform.is_valid(): f = metaform.save(commit=False) for instance in f: instance.updated_by = request.user instance.save() else: metaform = FormSet(instance=a) return render_to_response('nodes/form.html', {'form':metaform}) What is happening is that if I change any of the data then everything works ok and all the data gets updated. However if I don't change any of the data then the data is not updated. i.e. only entries which are changed go through the for loop to be saved. I guess this makes sense as there is no point saving data if it has not changed. However I need to go through and save every object in the form regardless of whether it has any changes on not. So my question is how do I override this so that it goes through and saves every record whether it has any changes or not? Hope this makes sense Thanks

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• how does serializable work in java?

  - by Karl Trumstedt

  If I have an instance of a class that I store in a session I need to make it serializable. This class has a static variable, will this be serialized in every instance stored? The static variable is a reference to a cache containing a lot of data in the background. Will all of this data be serialized? If so, it seems preferable to make this variable transient and re-fetch the cache instance each time the instance is restored. Maybe not store the cache instance at all in the class. Will the constructor execute when a class is restored from a serialized state? if not is there any other method I can use to re-instate a transient variable?

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• Serialization of a TChan String

  - by J Fritsch

  I have declared the following type KEY = (IPv4, Integer) type TPSQ = TVar (PSQ.PSQ KEY POSIXTime) type TMap = TVar (Map.Map KEY [String]) data Qcfg = Qcfg { qthresh :: Int, tdelay :: Rational, cwpsq :: TPSQ, cwmap :: TMap, cw chan :: TChan String } deriving (Show) and would like this to be serializable in a sense that Qcfg can either be written to disk or be sent over the network. When I compile this I get the error No instances for (Show TMap, Show TPSQ, Show (TChan String)) arising from the 'deriving' clause of a data type declaration Possible fix: add instance declarations for (Show TMap, Show TPSQ, Show (TChan String)) or use a standalone 'deriving instance' declaration, so you can specify the instance context yourself When deriving the instance for (Show Qcfg) I am now not quite sure whether there is a chance at all to serialize my TChan although all individual nodes in it are members of the show class. For TMap and TPSQ I wonder whether there are ways to show the values in the TVar directly (because it does not get changed, so there should no need to lock it) without having to declare an instance that does a readTVar ?

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• How can I use Javascript to access sub-elements?

  - by Steve

  I am dynamically creating forms dynamically according to a users actions. It is an entry-box and a two "buttons" for each instance. Each instance will be wrapped in a unique div tag. What I tried to do without success is when I dynamically create the "button" I attach a function with the input variable containing the div of its instance. This a brief excerpt: var newDivClass = document.getElementById("instance"+1); button1.innerHTML = "<a href=\"#\" onclick=\"buttons("+newDivClass+");\" id=\"button1\"> Button1 </a>"; function buttons(selected) { //I want this to select the first instance //of button1 found within div newDivClass selected.getElementById("button1"); //I also tried //this.getElementById("button1"); //selected.getChildren[0]; } The problem appears to be in passing newDivClass to the the actual function.

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• flash core engine by Dinesh [closed]

  - by hdinesh

  This post was a dump of the following code (without the highlights). No question, just a dump. Please update this q. with a real question to have it reopened. You (the asker) risk to be flagged as spammer (if not already) and a bad reputation. This is a q/a site, not a site to promote your own code libraries. package facers { import flash.display.*; import flash.events.*; import flash.geom.ColorTransform; import flash.utils.Dictionary; import org.papervision3d.cameras.*; import org.papervision3d.scenes.*; import org.papervision3d.objects.*; import org.papervision3d.objects.special.*; import org.papervision3d.objects.primitives.*; import org.papervision3d.materials.*; import org.papervision3d.events.FileLoadEvent; import org.papervision3d.materials.special.*; import org.papervision3d.materials.shaders.*; import org.papervision3d.materials.utils.*; import org.papervision3d.lights.*; import org.papervision3d.render.*; import org.papervision3d.view.*; import org.papervision3d.events.InteractiveScene3DEvent; import org.papervision3d.events.*; import org.papervision3d.core.utils.*; import org.papervision3d.core.geom.renderables.Vertex3D; import caurina.transitions.*; public class Main extends Sprite { public var viewport :BasicView; public var displayObject :DisplayObject3D; private var light :PointLight3D; private var shadowPlane :Plane; private var dataArray :Array; private var material :BitmapFileMaterial; private var planeByContainer :Dictionary = new Dictionary(); private var paperSize :Number = 0.5; private var cloudSize :Number = 1500; private var rotSize :Number = 360; private var maxAlbums :Number = 50; private var num :Number = 0; public function Main():void { trace("START APPLICATION"); viewport = new BasicView(1024, 690, true, true, CameraType.FREE); viewport.camera.zoom = 50; viewport.camera.extra = { goPosition: new DisplayObject3D(),goTarget: new DisplayObject3D() }; addChild(viewport); displayObject = new DisplayObject3D(); viewport.scene.addChild(displayObject); createAlbum(); addEventListener(Event.ENTER_FRAME, onRenderEvent); } private function createAlbum() { dataArray = new Array("images/thums/pic1.jpg", "images/thums/pic2.jpg", "images/thums/pic3.jpg", "images/thums/pic4.jpg", "images/thums/pic5.jpg", "images/thums/pic6.jpg", "images/thums/pic7.jpg", "images/thums/pic8.jpg", "images/thums/pic9.jpg", "images/thums/pic10.jpg", "images/thums/pic1.jpg", "images/thums/pic2.jpg", "images/thums/pic3.jpg", "images/thums/pic4.jpg", "images/thums/pic5.jpg", "images/thums/pic6.jpg", "images/thums/pic7.jpg", "images/thums/pic8.jpg", "images/thums/pic9.jpg", "images/thums/pic10.jpg"); for (var i:int = 0; i < dataArray.length; i++) { material = new BitmapFileMaterial(dataArray[i]); material.doubleSided = true; material.addEventListener(FileLoadEvent.LOAD_COMPLETE, loadMaterial); } } public function loadMaterial(event:Event) { var plane:Plane = new Plane(material, 300, 180); displayObject.addChild(plane); var _x:int = Math.random() * cloudSize - cloudSize/2; var _y:int = Math.random() * cloudSize - cloudSize/2; var _z:int = Math.random() * cloudSize - cloudSize/2; var _rotationX:int = Math.random() * rotSize; var _rotationY:int = Math.random() * rotSize; var _rotationZ:int = Math.random() * rotSize; Tweener.addTween(plane, { x:_x, y:_y, z:_z, rotationX:_rotationX, rotationY:_rotationY, rotationZ:_rotationZ, time:5, transition:"easeIn" } ); } protected function onRenderEvent(event:Event):void { var rotY: Number = (mouseY-(stage.stageHeight/2))/(900/2)*(1200); var rotX: Number = (mouseX-(stage.stageWidth/2))/(600/2)*(-1200); displayObject.rotationY = viewport.camera.x + (rotX - viewport.camera.x) / 50; displayObject.rotationX = viewport.camera.y + (rotY - viewport.camera.y) / 30; viewport.singleRender(); } } } package designLab.events { import flash.display.BlendMode; import flash.display.Sprite; import flash.events.Event; import flash.filters.BlurFilter; // Import designLab import designLab.layer.IntroLayer; import designLab.shadow.ShadowCaster; import designLab.utils.LayerConstant; // Import Papervision3D import org.papervision3d.cameras.*; import org.papervision3d.scenes.*; import org.papervision3d.objects.*; import org.papervision3d.objects.special.*; import org.papervision3d.objects.primitives.*; import org.papervision3d.materials.*; import org.papervision3d.materials.special.*; import org.papervision3d.materials.shaders.*; import org.papervision3d.materials.utils.*; import org.papervision3d.lights.*; import org.papervision3d.render.*; import org.papervision3d.view.*; import org.papervision3d.events.InteractiveScene3DEvent; import org.papervision3d.events.*; import org.papervision3d.core.utils.*; import org.papervision3d.core.geom.renderables.Vertex3D; public class CoreEnging extends Sprite { public var viewport :BasicView; // Create BasicView public var displayObject :DisplayObject3D; // Create DisplayObject public var shadowCaster :ShadowCaster; // Create ShadowCaster private var light :PointLight3D; // Create PointLight private var shadowPlane :Plane; // Create Plane private var layer :LayerConstant; // Create constant resource layer private static var instance :CoreEnging; // Create CoreEnging class static instance // CoreEnging class static instance mathod function public static function getinstance() { if (instance != null) return instance; else { instance = new CoreEnging(); return instance; } } // CoreEnging constrictor public function CoreEnging () { trace("INFO: Design Lab Application : Core Enging v0.1"); layer = new LayerConstant(); viewport = new BasicView(900, 600, true, true, CameraType.FREE); // pass the width, height, scaleToStage, interactive, cameraType to BasicView viewport.camera.zoom = 100; // Define the zoom level of camera addChild(viewport); createFloor(); // Create the floor displayObject = new DisplayObject3D(); // Create new instance of DisplayObject viewport.scene.addChild(displayObject); // Add the DisplayObject to the BasicView light = new PointLight3D(); // Create new instance of PointLight light.z = -50; // Position the Z of create instance light.x = 0; //Position the X of create instance light.rotationZ = 45; //Position the rotation angel of the Z of create instance light.y = 500; //Position the Y of create instance shadowCaster = new ShadowCaster("shadow", 0x000000, BlendMode.MULTIPLY, .1, [new BlurFilter(20, 20, 1)]); // pass shadowcaster name, color, blend mode, alpha and filters shadowCaster.setType(ShadowCaster.SPOTLIGHT); // Define the shadow type addEventListener(Event.ENTER_FRAME, onRenderEvent); // Add frame render event } // Start create floor public function createFloor() { var spr:Sprite = new Sprite(); // Create Sprite spr.graphics.beginFill(0xFFFFFF); // Define the fill color for sprite spr.graphics.drawRect(0, 0, 600, 600); // Define the X, Y, width, height of the sprite var sprMaterial:MovieMaterial = new MovieMaterial(spr, true, true, true); //Create a texture from an existing sprite instance shadowPlane = new Plane(sprMaterial, 2000, 2000, 1, 1); // create new instance of the Plane and pass the texture material, width, height, segmentsW and segmentsH shadowPlane.rotationX = 80; //Position the rotation angel of the X of Plane shadowPlane.y = -200; //Position the Y of Plane viewport.scene.addChild(shadowPlane); // Add the Plane to the BasicView } // switch method function of the page layer control public function addLayer(type:String) { switch (type) { case layer.INTRO: var intro:IntroLayer = new IntroLayer(); break; } } // Create get mathod function for DisplayObject public function getDisplayObject():DisplayObject3D { return displayObject; } // Create get mathod function for BasicView public function getViewport():BasicView { return viewport; } // Rendering function protected function onRenderEvent(event:Event):void { var rotY: Number = (mouseY-(stage.stageHeight/2))/(900/2)*(1200); var rotX: Number = (mouseX-(stage.stageWidth/2))/(600/2)*(-1200); displayObject.rotationY = viewport.camera.x + (rotX - viewport.camera.x) / 50; displayObject.rotationX = viewport.camera.y + (rotY - viewport.camera.y) / 30; // Remove the shadow shadowCaster.invalidate(); // create new shadow on DisplayObject move shadowCaster.castModel(displayObject, light, shadowPlane); viewport.singleRender(); } } } package designLab.layer { import flash.display.Sprite; import flash.events.Event; // Import designLab import designLab.materials.iBusinessCard; import designLab.events.CoreEnging; // Import Papervision3D import org.papervision3d.objects.primitives.Cube; import org.papervision3d.materials.ColorMaterial; import org.papervision3d.materials.MovieMaterial; public class IntroLayer { // IntroLayer constrictor public function IntroLayer() { trace("INFO: Load Intro layer"); var indexDP:DP_index = new DP_index(); //Create the library MovieClip var blackMaterial:MovieMaterial = new MovieMaterial(indexDP, true); //Create a texture from an existing library MovieClip instance blackMaterial.smooth = true; blackMaterial.doubleSided = false; var mycolor:ColorMaterial = new ColorMaterial(0x000000); //Create solid color material var mycard:iBusinessCard = new iBusinessCard(blackMaterial, blackMaterial, mycolor, 372, 10, 207); // Create custom 3D cube object to pass the Front, Back, All, CubeWidth, CubeDepth and CubeHeight CoreEnging.getinstance().getDisplayObject().addChild(mycard.create3DCube()); // Add the custom 3D cube to the DisplayObject } } } package designLab.materials { import flash.display.*; import flash.events.*; // Import Papervision3D import org.papervision3d.materials.*; import org.papervision3d.materials.utils.MaterialsList; import org.papervision3d.objects.primitives.Cube; public class iBusinessCard extends Sprite { private var materialsList :MaterialsList; private var cube :Cube; private var Front :MovieMaterial = new MovieMaterial(); private var Back :MovieMaterial = new MovieMaterial(); private var All :ColorMaterial = new ColorMaterial(); private var CubeWidth :Number; private var CubeDepth :Number; private var CubeHeight :Number; public function iBusinessCard(Front:MovieMaterial, Back:MovieMaterial, All:ColorMaterial, CubeWidth:Number, CubeDepth:Number, CubeHeight:Number) { setFront(Front); setBack(Back); setAll(All); setCubeWidth(CubeWidth); setCubeDepth(CubeDepth); setCubeHeight(CubeHeight); } public function create3DCube():Cube { materialsList = new MaterialsList(); materialsList.addMaterial(Front, "front"); materialsList.addMaterial(Back, "back"); materialsList.addMaterial(All, "left"); materialsList.addMaterial(All, "right"); materialsList.addMaterial(All, "top"); materialsList.addMaterial(All, "bottom"); cube = new Cube(materialsList, CubeWidth, CubeDepth, CubeHeight); cube.x = 0; cube.y = 0; cube.z = 0; cube.rotationY = 180; return cube; } public function setFront(Front:MovieMaterial) { this.Front = Front; } public function getFront():MovieMaterial { return Front; } public function setBack(Back:MovieMaterial) { this.Back = Back; } public function getBack():MovieMaterial { return Back; } public function setAll(All:ColorMaterial) { this.All = All; } public function getAll():ColorMaterial { return All; } public function setCubeWidth(CubeWidth:Number) { this.CubeWidth = CubeWidth; } public function getCubeWidth():Number { return CubeWidth; } public function setCubeDepth(CubeDepth:Number) { this.CubeDepth = CubeDepth; } public function getCubeDepth():Number { return CubeDepth; } public function setCubeHeight(CubeHeight:Number) { this.CubeHeight = CubeHeight; } public function getCubeHeight():Number { return CubeHeight; } } } package designLab.shadow { import flash.display.Sprite; import flash.filters.BlurFilter; import flash.geom.Point; import flash.geom.Rectangle; import flash.utils.Dictionary; import org.papervision3d.core.geom.TriangleMesh3D; import org.papervision3d.core.geom.renderables.Triangle3D; import org.papervision3d.core.geom.renderables.Vertex3D; import org.papervision3d.core.math.BoundingSphere; import org.papervision3d.core.math.Matrix3D; import org.papervision3d.core.math.Number3D; import org.papervision3d.core.math.Plane3D; import org.papervision3d.lights.PointLight3D; import org.papervision3d.materials.MovieMaterial; import org.papervision3d.objects.DisplayObject3D; import org.papervision3d.objects.primitives.Plane; public class ShadowCaster { private var vertexRefs:Dictionary; private var numberRefs:Dictionary; private var lightRay:Number3D = new Number3D() private var p3d:Plane3D = new Plane3D(); public var color:uint = 0; public var alpha:Number = 0; public var blend:String = ""; public var filters:Array; public var uid:String; private var _type:String = "point"; private var dir:Number3D; private var planeBounds:Dictionary; private var targetBounds:Dictionary; private var models:Dictionary; public static var DIRECTIONAL:String = "dir"; public static var SPOTLIGHT:String = "spot"; public function ShadowCaster(uid:String, color:uint = 0, blend:String = "multiply", alpha:Number = 1, filters:Array=null) { this.uid = uid; this.color = color; this.alpha = alpha; this.blend = blend; this.filters = filters ? filters : [new BlurFilter()]; numberRefs = new Dictionary(true); targetBounds = new Dictionary(true); planeBounds = new Dictionary(true); models = new Dictionary(true); } public function castModel(model:DisplayObject3D, light:PointLight3D, plane:Plane, faces:Boolean = true, cull:Boolean = false):void{ var ar:Array; if(models[model]) { ar = models[model]; }else{ ar = new Array(); getChildMesh(model, ar); models[model] = ar; } var reset:Boolean = true; for each(var t:TriangleMesh3D in ar){ if(faces) castFaces(light, t, plane, cull, reset); else castBoundingSphere(light, t, plane, 0.75, reset); reset = false; } } private function getChildMesh(do3d:DisplayObject3D, ar):void{ if(do3d is TriangleMesh3D) ar.push(do3d); for each(var d:DisplayObject3D in do3d.children) getChildMesh(d, ar); } public function setType(type:String="point"):void{ _type = type; } public function getType():String{ return _type; } public function castBoundingSphere(light:PointLight3D, target:TriangleMesh3D, plane:Plane, scaleRadius:Number=0.8, clear:Boolean = true):void{ var planeVertices:Array = plane.geometry.vertices; //convert to target space? var world:Matrix3D = plane.world; var inv:Matrix3D = Matrix3D.inverse(plane.transform); var lp:Number3D = new Number3D(light.x, light.y, light.z); Matrix3D.multiplyVector(inv, lp); p3d.setNormalAndPoint(plane.geometry.faces[0].faceNormal, new Number3D()); var b:BoundingSphere = target.geometry.boundingSphere; var bounds:Object = planeBounds[plane]; if(!bounds){ bounds = plane.boundingBox(); planeBounds[plane] = bounds; } var tbounds:Object = targetBounds[target]; if(!tbounds){ tbounds = target.boundingBox(); targetBounds[target] = tbounds; } var planeMovie:Sprite = Sprite(MovieMaterial(plane.material).movie); var movieSize:Point = new Point(planeMovie.width, planeMovie.height); var castClip:Sprite = getCastClip(plane); castClip.blendMode = this.blend; castClip.filters = this.filters; castClip.alpha = this.alpha; if(clear) castClip.graphics.clear(); vertexRefs = new Dictionary(true); var tlp:Number3D = new Number3D(light.x, light.y, light.z); Matrix3D.multiplyVector(Matrix3D.inverse(target.world), tlp); var center:Number3D = new Number3D(tbounds.min.x+tbounds.size.x*0.5, tbounds.min.y+tbounds.size.y*0.5, tbounds.min.z+tbounds.size.z*0.5); var dif:Number3D = Number3D.sub(lp, center); dif.normalize(); var other:Number3D = new Number3D(); other.x = -dif.y; other.y = dif.x; other.z = 0; other.normalize(); var cross:Number3D = Number3D.cross(new Number3D(plane.transform.n12, plane.transform.n22, plane.transform.n32), p3d.normal); cross.normalize(); //cross = new Number3D(-dif.y, dif.x, 0); //cross.normalize(); cross.multiplyEq(b.radius*scaleRadius); if(_type == DIRECTIONAL){ var oPos:Number3D = new Number3D(target.x, target.y, target.z); Matrix3D.multiplyVector(target.world, oPos); Matrix3D.multiplyVector(inv, oPos); dir = new Number3D(oPos.x-lp.x, oPos.y-lp.y, oPos.z-lp.z); } //numberRefs = new Dictionary(true); var pos:Number3D; var c2d:Point; var r2d:Point; //_type = SPOTLIGHT; pos = projectVertex(new Vertex3D(center.x, center.y, center.z), lp, inv, target.world); c2d = get2dPoint(pos, bounds.min, bounds.size, movieSize); pos = projectVertex(new Vertex3D(center.x+cross.x, center.y+cross.y, center.z+cross.z), lp, inv, target.world); r2d = get2dPoint(pos, bounds.min, bounds.size, movieSize); var dx:Number = r2d.x-c2d.x; var dy:Number = r2d.y-c2d.y; var rad:Number = Math.sqrt(dx*dx+dy*dy); castClip.graphics.beginFill(color); castClip.graphics.moveTo(c2d.x, c2d.y); castClip.graphics.drawCircle(c2d.x, c2d.y, rad); castClip.graphics.endFill(); } public function getCastClip(plane:Plane):Sprite{ var planeMovie:Sprite = Sprite(MovieMaterial(plane.material).movie); var movieSize:Point = new Point(planeMovie.width, planeMovie.height); var castClip:Sprite;// = new Sprite(); if(planeMovie.getChildByName("castClip"+uid)) return Sprite(planeMovie.getChildByName("castClip"+uid)); else{ castClip = new Sprite(); castClip.name = "castClip"+uid; castClip.scrollRect = new Rectangle(0, 0, movieSize.x, movieSize.y); //castClip.alpha = 0.4; planeMovie.addChild(castClip); return castClip; } } public function castFaces(light:PointLight3D, target:TriangleMesh3D, plane:Plane, cull:Boolean=false, clear:Boolean = true):void{ var planeVertices:Array = plane.geometry.vertices; //convert to target space? var world:Matrix3D = plane.world; var inv:Matrix3D = Matrix3D.inverse(plane.transform); var lp:Number3D = new Number3D(light.x, light.y, light.z); Matrix3D.multiplyVector(inv, lp); var tlp:Number3D; if(cull){ tlp = new Number3D(light.x, light.y, light.z); Matrix3D.multiplyVector(Matrix3D.inverse(target.world), tlp); } //Matrix3D.multiplyVector(Matrix3D.inverse(target.transform), tlp); //p3d.setThreePoints(planeVertices[0].getPosition(), planeVertices[1].getPosition(), planeVertices[2].getPosition()); p3d.setNormalAndPoint(plane.geometry.faces[0].faceNormal, new Number3D()); if(_type == DIRECTIONAL){ var oPos:Number3D = new Number3D(target.x, target.y, target.z); Matrix3D.multiplyVector(target.world, oPos); Matrix3D.multiplyVector(inv, oPos); dir = new Number3D(oPos.x-lp.x, oPos.y-lp.y, oPos.z-lp.z); } var bounds:Object = planeBounds[plane]; if(!bounds){ bounds = plane.boundingBox(); planeBounds[plane] = bounds; } var castClip:Sprite = getCastClip(plane); castClip.blendMode = this.blend; castClip.filters = this.filters; castClip.alpha = this.alpha; var planeMovie:Sprite = Sprite(MovieMaterial(plane.material).movie); var movieSize:Point = new Point(planeMovie.width, planeMovie.height); if(clear) castClip.graphics.clear(); vertexRefs = new Dictionary(true); //numberRefs = new Dictionary(true); var pos:Number3D; var p2d:Point; var s2d:Point; var hitVert:Number3D = new Number3D(); for each(var t:Triangle3D in target.geometry.faces){ if( cull){ hitVert.x = t.v0.x; hitVert.y = t.v0.y; hitVert.z = t.v0.z; if(Number3D.dot(t.faceNormal, Number3D.sub(tlp, hitVert)) <= 0) continue; } castClip.graphics.beginFill(color); pos = projectVertex(t.v0, lp, inv, target.world); s2d = get2dPoint(pos, bounds.min, bounds.size, movieSize); castClip.graphics.moveTo(s2d.x, s2d.y); pos = projectVertex(t.v1, lp, inv, target.world); p2d = get2dPoint(pos, bounds.min, bounds.size, movieSize); castClip.graphics.lineTo(p2d.x, p2d.y); pos = projectVertex(t.v2, lp, inv, target.world); p2d = get2dPoint(pos, bounds.min, bounds.size, movieSize); castClip.graphics.lineTo(p2d.x, p2d.y); castClip.graphics.lineTo(s2d.x, s2d.y); castClip.graphics.endFill(); } } public function invalidate():void{ invalidateModels(); invalidatePlanes(); } public function invalidatePlanes():void{ planeBounds = new Dictionary(true); } public function invalidateTargets():void{ numberRefs = new Dictionary(true); targetBounds = new Dictionary(true); } public function invalidateModels():void{ models = new Dictionary(true); invalidateTargets(); } private function get2dPoint(pos3D:Number3D, min3D:Number3D, size3D:Number3D, movieSize:Point):Point{ return new Point((pos3D.x-min3D.x)/size3D.x*movieSize.x, ((-pos3D.y-min3D.y)/size3D.y*movieSize.y)); } private function projectVertex(v:Vertex3D, light:Number3D, invMat:Matrix3D, world:Matrix3D):Number3D{ var pos:Number3D = vertexRefs[v]; if(pos) return pos; var n:Number3D = numberRefs[v]; if(!n){ n = new Number3D(v.x, v.y, v.z); Matrix3D.multiplyVector(world, n); Matrix3D.multiplyVector(invMat, n); numberRefs[v] = n; } if(_type == SPOTLIGHT){ lightRay.x = light.x; lightRay.y = light.y; lightRay.z = light.z; }else{ lightRay.x = n.x-dir.x; lightRay.y = n.y-dir.y; lightRay.z = n.z-dir.z; } pos = p3d.getIntersectionLineNumbers(lightRay, n); vertexRefs[v] = pos; return pos; } } } package designLab.utils { public class LayerConstant { public const INTRO:String = "INTRO"; // Intro layer string constant } }*emphasized text*

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• Performing an upgrade from TFS 2008 to TFS 2010

  - by Enrique Lima

  I recently had to go through the process of migrating a TFS 2008 SP1 to a TFS 2010 environment. I will go into the details of the tasks that I went through, but first I want to explain why I define it as a migration and not an upgrade. When this environment was setup, based on support and limitations for TFS 2008, we used a 32 bit platform for the TFS Application Tier and Build Servers.  The Data Tier, since we were installing SP1 for TFS 2008, was done as a 64 bit installation.  We knew at that point that TFS 2010 was in the picture so that served as further motivation to make that a 64bit install of SQL Server.  The SQL Server at that point was a single instance (Default) installation too.  We had a pretty good strategy in place for backups of the databases supporting the environment (and this made the migration so much smoother), so we were pretty familiar with the databases and the purpose they serve. I am sure many of you that have gone through a TFS 2008 installation have encountered challenges and trials.  And likely even more so if you, like me, needed to configure your deployment for SSL.  So, frankly I was a little concerned about the process of migrating.  They say practice makes perfect, and this environment I worked on is in some way my brain child, so I was not ready nor willing for this to be a failure or something that would impact my client’s work. Prior to going through the migration process, we did the install of the environment.  The Data Tier was the same, with a new Named instance in place to host the 2010 install.  The Application Tier was in place too, and we did the DefaultCollection configuration to test and validate all components were in place as they should. Anyway, on to the tasks for the migration (thanks to Martin Hinselwood for his very thorough documentation): Close access to TFS 2008, you want to make sure all code is checked in and ready to go.  We stated a difference of 8 hours between code lock and the start of migration to give time for any unexpected delay.  How do we close access?  Stop IIS. Backup your databases.  Which ones? TfsActivityLogging TfsBuild TfsIntegration TfsVersionControl TfsWorkItemTracking TfsWorkItemTrackingAttachments Restore the databases to the new Named Instance (make sure you keep the same names) Now comes the fun part! The actual import/migration of the databases.  A couple of things happen here. The TfsIntegration database will be scanned, the other databases will be checked to validate they exist.  Those databases will go through a process of data being extracted and transferred to the TfsVersionControl database to then be renamed to Tfs_<Collection>. You will be using a tool called tfsconfig and the option import. This tool is located in the TFS 2010 installation path (C:\Program Files\Microsoft Team Foundation Server 2010\Tools),  the command to use is as follows:    tfsconfig import /sqlinstance:<instance> /collectionName:<name> /confirmed Where <instance> is going to be the SQL Server instance where you restored the databases to.  <name> is the name you will give the collection. And to explain /confirmed, well this means you have done a backup of the databases, why?  well remember you are going to merge the databases you restored when you execute the tfsconfig import command. The process will go through about 200 tasks, once it completes go to Team Foundation Server Administration Console and validate your imported databases and contents. We’ll keep this manageable, so the next post is about how to complete that implementation with the SSL configuration.

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• Web Application Integration Steps in OAM 11gR2 (High Level)

  - by Venkata Srikanth

  Install OAM, Webtier (OHS) and WebGate as per the standard installation steps. Create a WebGate instance (i.e deploy WebGate) A WebGate instance must be created that will copy required bits of agent from WEBGATE_HOME to WebGate instance location that shares the same INSTANCE_HOME with OHS ./deployWebGateInstance.sh –w /Oracle/Middleware/Oracle_WT1/instances/instance1/config/ohs1 –oh /Oracle/Middleware/Oracle_OAMWebGate1 Note: Here –w flag indicates OHS instance folder and –oh indicates the WebGate Oracle home Configure WebGate In the webgate configuration the EditHttpdConf utility will copy OUI instantiated apache_webgate.template from WEBGATE_HOME to webgate instance location (renamed to webgate.conf), and update httpd.conf with one additional line to include webgate.conf. export LD_LIBRARY_PATH=$ LD_LIBRARY_PATH:/Oracle/Middleware/Oracle_WT1/lib Navigate to /Oracle/Middleware/Oracle_OAMWebGate1/webgate/ohs/tools/setup/InstallTools ./EditHttpdConf –w /Oracle/Middleware/Oracle_WT1/instances/instace1/config/OHS/ohs1 –oh /Oracle/Middleware/Oracle_OAMWebGate1 –o webgate.conf Register WebGate Use RREG tool to register the OAM 11G WebGate Navigate to /Oracle/Middleware/Oracle_IDM1/oam/server/rreg/input Edit OAM11Grequest.xml. Change the specific xml content to include the weblogic admin URL, agentBaseURL, host identifier etc.. Navigate to /Oracle/Middleware/Oracle_IDM1/oam/server/rreg/bin Set permissions to oamreg.sh à chmod 777 oamreg.sh Edit oamreg.sh and set OAM_REG_HOME=/Oracle/Middleware/Oracle_IDM1/oam/server/rreg ./oamreg.sh inband input/OAM11Grequest.xml Enter the WebLogic admin credentials when prompted. After performing the above steps, there will be two artifcats created under Oracle/Middleware/Oracle_IDM1/oam/server/rreg/output, namely ObAccessClient.xml (Stroing webgate config parameters) and cwallet.sso (storing the agent key). These files must be copied to WebGate instance config folder (/Oracle/Middleware/Oracle_WT1/instances/instance1/config/ohs1/webgate/config) Restart OHS Deploy the web application (myApp) in WebLogic application server Proxy Configuration in OHS The mod_wl_ohs module enables requests to be proxied from Oracle HTTP Server 11g to Oracle WebLogic Server. Navigate to /Oracle/Middleware/Oracle_WT1/instances/instance1/config/OHS/ohs1 Edit mod_wl_ohs.conf file to include the following: <IfModule weblogic_module> WebLogicHost <WEBLOGIC_HOST> WebLogicPort <WEBLOGIC_PORT> # Debug ON # WLLogFile /tmp/weblogic.log MatchExpression *.jsp </IfModule> <Location /myApp> SetHandler weblogic-handler # PathTrim /weblogic # ErrorPage http:/WEBLOGIC_HOME:WEBLOGIC_PORT/ </Location> Note: Here WEBLOGIC_HOST and WEBLOGIC_PORT are the WebLogic admin server host and port respectively Restart OHS. Now if we access the web application URL with OHS host and port (Ex: http://OHS_HOST:<OHS_PORT>/myApp) so that the requests will be proxied to WebLogic server. Create a new application domain Login to OAM Admin Console Navigate to Shared Componentsà Authentication Schemesà Create Authentication Scheme (Ex: LDAP Auth Scheme. Here the scheme is assoicated with LDAP Authentication Module) Navigate to Policy Configuration à Application Domain à Create Application Domain Enter the Application Domain Name and Click Apply. Navigate to Resources tab and add the resource urls (Web Application URLs that needs to be protected) Navigate to Authentication Policy tab à Create a new authentication ploicy by providing the Resource URLs (The sample Web Application URLs) and Authentication Scheme. Navigate to Authorization Policy tab à Create a new authorization policy à Enter authorization policy name and navigate to Resource Tab à Attach the Reource URL, Host Identifiers here. Navigate to Conditions tab à Add the conditions like whom to allow and whom to deny access. Navigate to Rules tab à Crate the Allow Rule and Deny Rule with the available conditions from the previous step so that the Authorization Policy may authorize the logins. Navigate to Resources tab and attach the Authentication and Authorization plocies created in the above steps. Test the Web Application Integration.

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• How would you gather client's data on Google App Engine without using Datastore/Backend Instances too much?

  - by ruslan

  I'm relatively new to StackExchange and not sure if it's appropriate place to ask design question. Site gives me a hint "The question you're asking appears subjective and is likely to be closed". Please let me know. Anyway.. One of the projects I'm working on is online survey engine. It's my first big commercial project on Google App Engine. I need your advice on how to collect stats and efficiently record them in DataStore without bankrupting me. Initial requirements are: After user finishes survey client sends list of pairs [ID (int) + PercentHit (double)]. This list shows how close answers of this user match predefined answers of reference answerers (which identified by IDs). I call them "target IDs". Creator of the survey wants to see aggregated % for given IDs for last hour, particular timeframe or from the beginning of the survey. Some surveys may have thousands of target/reference answerers. So I created entity public class HitsStatsDO implements Serializable { @Id transient private Long id; transient private Long version = (long) 0; transient private Long startDate; @Parent transient private Key parent; // fake parent which contains target id @Transient int targetId; private double avgPercent; private long hitCount; } But writing HitsStatsDO for each target from each user would give a lot of data. For instance I had a survey with 3000 targets which was answered by ~4 million people within one week with 300K people taking survey in first day. Even if we assume they were answering it evenly for 24 hours it would give us ~1040 writes/second. Obviously it hits concurrent writes limit of Datastore. I decided I'll collect data for one hour and save that, that's why there are avgPercent and hitCount in HitsStatsDO. GAE instances are stateless so I had to use dynamic backend instance. There I have something like this: // Contains stats for one hour private class Shard { ReadWriteLock lock = new ReentrantReadWriteLock(); Map<Integer, HitsStatsDO> map = new HashMap<Integer, HitsStatsDO>(); // Key is target ID public void saveToDatastore(); public void updateStats(Long startDate, Map<Integer, Double> hits); } and map with shard for current hour and previous hour (which doesn't stay here for long) private HashMap<Long, Shard> shards = new HashMap<Long, Shard>(); // Key is HitsStatsDO.startDate So once per hour I dump Shard for previous hour to Datastore. Plus I have class LifetimeStats which keeps Map<Integer, HitsStatsDO> in memcached where map-key is target ID. Also in my backend shutdown hook method I dump stats for unfinished hour to Datastore. There is only one major issue here - I have only ONE backend instance :) It raises following questions on which I'd like to hear your opinion: Can I do this without using backend instance ? What if one instance is not enough ? How can I split data between multiple dynamic backend instances? It hard because I don't know how many I have because Google creates new one as load increases. I know I can launch exact number of resident backend instances. But how many ? 2, 5, 10 ? What if I have no load at all for a week. Constantly running 10 backend instances is too expensive. What do I do with data from clients while backend instance is dead/restarting? Thank you very much in advance for your thoughts.

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• Bug in Delphi XE RegularExpressions Unit

  - by Jan Goyvaerts

  Using the new RegularExpressions unit in Delphi XE, you can iterate over all the matches that a regex finds in a string like this: procedure TForm1.Button1Click(Sender: TObject); var RegEx: TRegEx; Match: TMatch; begin RegEx := TRegex.Create('\w+'); Match := RegEx.Match('One two three four'); while Match.Success do begin Memo1.Lines.Add(Match.Value); Match := Match.NextMatch; end end; Or you could save yourself two lines of code by using the static TRegEx.Match call: procedure TForm1.Button2Click(Sender: TObject); var Match: TMatch; begin Match := TRegEx.Match('One two three four', '\w+'); while Match.Success do begin Memo1.Lines.Add(Match.Value); Match := Match.NextMatch; end end; Unfortunately, due to a bug in the RegularExpressions unit, the static call doesn’t work. Depending on your exact code, you may get fewer matches or blank matches than you should, or your application may crash with an access violation. The RegularExpressions unit defines TRegEx and TMatch as records. That way you don’t have to explicitly create and destroy them. Internally, TRegEx uses TPerlRegEx to do the heavy lifting. TPerlRegEx is a class that needs to be created and destroyed like any other class. If you look at the TRegEx source code, you’ll notice that it uses an interface to destroy the TPerlRegEx instance when TRegEx goes out of scope. Interfaces are reference counted in Delphi, making them usable for automatic memory management. The bug is that TMatch and TGroupCollection also need the TPerlRegEx instance to do their work. TRegEx passes its TPerlRegEx instance to TMatch and TGroupCollection, but it does not pass the instance of the interface that is responsible for destroying TPerlRegEx. This is not a problem in our first code sample. TRegEx stays in scope until we’re done with TMatch. The interface is destroyed when Button1Click exits. In the second code sample, the static TRegEx.Match call creates a local variable of type TRegEx. This local variable goes out of scope when TRegEx.Match returns. Thus the reference count on the interface reaches zero and TPerlRegEx is destroyed when TRegEx.Match returns. When we call MatchAgain the TMatch record tries to use a TPerlRegEx instance that has already been destroyed. To fix this bug, delete or rename the two RegularExpressions.dcu files and copy RegularExpressions.pas into your source code folder. Make these changes to both the TMatch and TGroupCollection records in this unit: Declare FNotifier: IInterface; in the private section. Add the parameter ANotifier: IInterface; to the Create constructor. Assign FNotifier := ANotifier; in the constructor’s implementation. You also need to add the ANotifier: IInterface; parameter to the TMatchCollection.Create constructor. Now try to compile some code that uses the RegularExpressions unit. The compiler will flag all calls to TMatch.Create, TGroupCollection.Create and TMatchCollection.Create. Fix them by adding the ANotifier or FNotifier parameter, depending on whether ARegEx or FRegEx is being passed. With these fixes, the TPerlRegEx instance won’t be destroyed until the last TRegEx, TMatch, or TGroupCollection that uses it goes out of scope or is used with a different regular expression.

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• How can I gather client's data on Google App Engine without using Datastore/Backend Instances too much?

  - by ruslan

  One of the projects I'm working on is online survey engine. It's my first big commercial project on Google App Engine. I need your advice on how to collect stats and efficiently record them in DataStore without bankrupting me. Initial requirements are: After user finishes survey client sends list of pairs [ID (int) + PercentHit (double)]. This list shows how close answers of this user match predefined answers of reference answerers (which identified by IDs). I call them "target IDs". Creator of the survey wants to see aggregated % for given IDs for last hour, particular timeframe or from the beginning of the survey. Some surveys may have thousands of target/reference answerers. So I created entity public class HitsStatsDO implements Serializable { @Id transient private Long id; transient private Long version = (long) 0; transient private Long startDate; @Parent transient private Key parent; // fake parent which contains target id @Transient int targetId; private double avgPercent; private long hitCount; } But writing HitsStatsDO for each target from each user would give a lot of data. For instance I had a survey with 3000 targets which was answered by ~4 million people within one week with 300K people taking survey in first day. Even if we assume they were answering it evenly for 24 hours it would give us ~1040 writes/second. Obviously it hits concurrent writes limit of Datastore. I decided I'll collect data for one hour and save that, that's why there are avgPercent and hitCount in HitsStatsDO. GAE instances are stateless so I had to use dynamic backend instance. There I have something like this: // Contains stats for one hour private class Shard { ReadWriteLock lock = new ReentrantReadWriteLock(); Map<Integer, HitsStatsDO> map = new HashMap<Integer, HitsStatsDO>(); // Key is target ID public void saveToDatastore(); public void updateStats(Long startDate, Map<Integer, Double> hits); } and map with shard for current hour and previous hour (which doesn't stay here for long) private HashMap<Long, Shard> shards = new HashMap<Long, Shard>(); // Key is HitsStatsDO.startDate So once per hour I dump Shard for previous hour to Datastore. Plus I have class LifetimeStats which keeps Map<Integer, HitsStatsDO> in memcached where map-key is target ID. Also in my backend shutdown hook method I dump stats for unfinished hour to Datastore. There is only one major issue here - I have only ONE backend instance :) It raises following questions on which I'd like to hear your opinion: Can I do this without using backend instance ? What if one instance is not enough ? How can I split data between multiple dynamic backend instances? It hard because I don't know how many I have because Google creates new one as load increases. I know I can launch exact number of resident backend instances. But how many ? 2, 5, 10 ? What if I have no load at all for a week. Constantly running 10 backend instances is too expensive. What do I do with data from clients while backend instance is dead/restarting?

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• Investigating Strategies For Functional Decomposition

  - by Liam McLennan

  Introducing Functional Decomposition Before I begin I must apologise. I think I am using the term ‘functional decomposition’ loosely, and probably incorrectly. For the purpose of this article I use functional decomposition to mean the recursive splitting of a large problem into increasingly smaller ones, so that the one large problem may be solved by solving a set of smaller problems. The justification for functional decomposition is that the decomposed problem is more easily solved. As software developers we recognise that the smaller pieces are more easily tested, since they do less and are more cohesive. Functional decomposition is important to all scientific pursuits. Once we understand natural selection we can start to look for humanities ancestral species, once we understand the big bang we can trace our expanding universe back to its origin. Isaac Newton acknowledged the compositional nature of his scientific achievements: If I have seen further than others, it is by standing upon the shoulders of giants   The Two Strategies For Functional Decomposition of Computer Programs Private Methods When I was working on my undergraduate degree I was taught to functionally decompose problems by using private methods. Consider the problem of painting a house. The obvious solution is to solve the problem as a single unit: public void PaintAHouse() { // all the things required to paint a house ... } We decompose the problem by breaking it into parts: public void PaintAHouse() { PaintUndercoat(); PaintTopcoat(); } private void PaintUndercoat() { // everything required to paint the undercoat } private void PaintTopcoat() { // everything required to paint the topcoat } The problem can be recursively decomposed until a sufficiently granular level of detail is reached: public void PaintAHouse() { PaintUndercoat(); PaintTopcoat(); } private void PaintUndercoat() { prepareSurface(); fetchUndercoat(); paintUndercoat(); } private void PaintTopcoat() { fetchPaint(); paintTopcoat(); } According to Wikipedia, at least one computer programmer has referred to this process as “the art of subroutining”. The practical issues that I have encountered when using private methods for decomposition are: To preserve the top level API all of the steps must be private. This means that they can’t easily be tested. The private methods often have little cohesion except that they form part of the same solution. Decomposing to Classes The alternative is to decompose large problems into multiple classes, effectively using a class instead of each private method. The API delegates to related classes, so the API is not polluted by the sub-steps of the problem, and the steps can be easily tested because they are each in their own highly cohesive class. Additionally, I think that this technique facilitates better adherence to the Single Responsibility Principle, since each class can be decomposed until it has precisely one responsibility. Revisiting my previous example using class composition: public class HousePainter { private undercoatPainter = new UndercoatPainter(); private topcoatPainter = new TopcoatPainter(); public void PaintAHouse() { undercoatPainter.Paint(); topcoatPainter.Paint(); } } Summary When decomposing a problem there is more than one way to represent the sub-problems. Using private methods keeps the logic in one place and prevents a proliferation of classes (thereby following the four rules of simple design) but the class decomposition is more easily testable and more compatible with the Single Responsibility Principle.

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• Call functions in AutoIt DLL using Python ctypes

  - by Josh

  I want to call functions from an AutoIt dll, that I found at C:\Program Files (x86)\AutoIt3\AutoItX\AutoItX3.dll using Python. I know I could use win32com.client.Dispatch("AutoItX3.Control") but I can't install the application or register anything in the system. So far, this is where I am: from ctypes import * path = r"C:\Program Files (x86)\AutoIt3\AutoItX\AutoItX3.dll" autoit = windll.LoadLibrary(path) Here are the methods that works: autoit.AU3_WinMinimizeAll() # windows were successfully minimized. autoit.AU3_Sleep(1000) # sleeps 1 sec. Here is my problem, python is crashing when I call other methods like this one. I get python.exe has stopped working from windows... autoit.AU3_WinGetHandle('Untitled - Notepad', '') And some other methods are not crashing python but are just not working. This one doesn't close the window and return 0: autoit.AU3_WinClose('Untitled - Notepad', '') And this other one return 1 but the window is still minimized: autoit.AU3_WinActivate('Untitled - Notepad', '') I've tested the examples with with Dispatch("AutoItX3.Control") and everything is working like expected. It seems like methods that should return something other than a string are crashing python. But still, others like WinClose are not even working... Thank you in advance for your help! EDIT: These methods are now working when using unicode strings: autoit.AU3_WinClose(u'Untitled - Notepad', u'') autoit.AU3_WinActivate(u'Untitled - Notepad', u'') And I found the prototype for AU3_WinGetHandle: AU3_API void WINAPI AU3_WinGetHandle(const char szTitle, /[in,defaultvalue("")]*/const char *szText, char *szRetText, int nBufSize); Now I see that I should get the handle from szRetText but I am not sure how... I tried the following without success: from ctypes.wintypes import LPCWSTR, INT, POINTER AU3_WinGetHandle.argtypes = (LPCWSTR, LPCWSTR, POINTER(LPCWSTR), INT) s = c_wchar_p() print AU3_WinGetHandle(u'Untitled - Notepad', u'', byref(s), 100) # prints 1 print s # prints c_wchar_p(u'') Any idea how to retrive the handle from szRetText?

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• Rails3 and Paperclip

  - by arkannia

  Hi, I have migrated my application from rails 2.3 to rails3 and i have a problem with paperclip. I saw there was a branch for rails3 on paperclip git. So I added "gem 'paperclip', :git = 'git://github.com/thoughtbot/paperclip.git', :branch = 'rails3'" into the Gemfile and launch the command bundle install. Once paperclip installed, the upload worked fine but not the styles. I saw a hack to fix it. # in lib/paperclip/attachment.rb at line 293 def callback which #:nodoc: # replace this line... # instance.run_callbacks(which, @queued_for_write){|result,obj| result == false } # with this: instance.run_callbacks(which, @queued_for_write) end The styles are ok after that, but i'm not able to active the processor. My code is : has_attached_file :image, :default_url => "/images/nopicture.jpg", :styles => { :large => "800x600>", :cropped => Proc.new { |instance| "#{instance.width}x#{instance.height}>" }, :crop => "300x300>" }, :processors => [:cropper] My processor is located in RAILS_APP/lib/paperclip_processors/cropper.rb and contains : module Paperclip class Cropper < Thumbnail def transformation_command if crop_command and !skip_crop? crop_command + super.sub(/ -crop \S+/, '') else super end end def crop_command target = @attachment.instance trans = ""; trans << " -crop #{target.crop_w}x#{target.crop_h}+#{target.crop_x}+#{target.crop_y}" if target.cropping? trans << " -resize \"#{target.width}x#{target.height}\"" trans end def skip_crop? ["800x600>", "300x300>"].include?(@target_geometry.to_s) end end end My problem is that i got this error message : uninitialized constant Paperclip::Cropper The cropped processor is not loaded. Is anybody has an idea to fix that ? For information my application works fine on rails 2.3.4.

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• tolua++: Adding lua functions to a C++ class that has been exported to Lua

  - by skyeagle

  I am using tolua++ to export some C++ classes to Lua. My understanding that each class is 'implemented' on the lua side, as a lua table. I am wondering if it is possible therefore, to add new (Lua) methods to the C++ object table so that I can achieve the effect of adding new methods to the C++ class. Assume that I am exporting the class Foobar. Methods of Foobar will be accessisble in Lua as follows: Foobar:method1() Foobar:method2() ... etc. I would like to be able to add new methods (newmethod1, and newmethod2) to the Foobar table "object" I have the following questions: Is it possible to 'extend' the functionality of an exported C++ object in the manner I described above? How would one go about add new functions to the Foobar table? (I am relatively new to Lua)

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• How to prepopulate an Outlook MailItem and avoiding a com Exception from the object model guard

  - by torrente

  Hi, I work for a company that develops a CRM tool and offers integration with MS Office(2003 & 2007) from windows XP to 7. (I'm working using Win7) My task is to call an Outlook instance (using C#) from this CRM tool when the user wants to send an email and prepopulate with data of the CRM tool (email, recipient, etc..) All of this already works just fine. The problem I'm having is that Outlook's "object model guard" is throwing com Exception (Operation aborted (Exception from HRESULT: 0x80004004 (E_ABORT))) the moment I try to read a protected value from the mailItem (such as mail.bodyHTML). Example Snippet: using MSOutlook = Microsoft.Office.Interop.Outlook; //untrusted Instance _outlook = new MSOutlook.Application(); MSOutlook.MailItem mail = (MSOutlook.MailItem)_outlook.CreateItem(MSOutlook.OlItemType.olMailItem); //this where the Exception occurs string outlookStdHTMLBody = mail.HTMLBody; I've done quite a bit of reading and know that my Outlook Instance (derived by using new Application) is considered untrusted and therefore the "omg" kicks in. I do have a workaround for development: I'm running VS2010 as Administrator and if I run Outlook as Administrator as well - all is good. I suppose this is due to them having the same integrity levels(high) and the UAC(?) is not complaining. But that just ain't the way to go for deployment. Now the question is: Is there a way to obtain a trusted instance of Outlook so that I can avoid this exception? I've already read that when developing an Office Add-In using VSTO one can obtain a trusted Instance from the OnComplete event and/or using "ThisAddin" But I "merely" want to start an outlook instance and preopulate it, and do not want to develop an Add-In since this is not the requirement. And to make it clear - I have no problem with pop ups informing the user that outlook is being accessed - I just want to get rid of the exception! So how can I get around this problem using code? Any help is highly appreciated! Thomas

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• Example: Objective C method alongside a php method

  - by Nic Hubbard

  I am very used to javascript and php programing, and I just jumped into programing Objective C. After working with it for a few weeks, the methods still confused me, as to how it is passing params, and how the methods are named. Since I am used to php, I am used to seeing: function myFunc($param1, $param2, $param3, $param4) { return FALSE; } Could someone show me how this would be written in Objective C, so that I can get used to writing methods that have parameters?

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• Problem retrieving multiple instances of the same asp.net session variable

  - by sw1sh

  I'm having problems with retrieving multiple instances of a session variable from an InProc session state. In the following code I persist a simple BusinessObject into a session variable on the Page_Load event. On the click of a button I try to retrieve the object back into 2 new declared instances of the same BusinessObject. All works great until I change one of the properties in the first instance, it changes the second instance as well. Is this normal behaviour? I would have thought as these were new instances they wouldn’t demonstrate static behaviour? Any ideas where I'm going wrong? Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load If Not Page.IsPostBack Then ' create a new instance of a business object and set a containg variable Dim BO As New BusinessObject BO.SomeVariable = "test" ' persist to inproc session Session("BO") = BO End If End Sub Protected Sub btnRetrieveSessionVariable_Click(ByVal sender As Object, ByVal e As EventArgs) Handles btnRetrieveSessionVariable.Click ' retrieve the session variable to a new instance of BusinessObject Dim BO1 As New BusinessObject If Not Session("BO") Is Nothing Then BO1 = Session("BO") ' retrieve the session variable to a new instance of BusinessObject Dim BO2 As New BusinessObject If Not Session("BO") Is Nothing Then BO2 = Session("BO") ' change the property value on the first instance BO1.SomeVariable = "test2" ' why has this changed on both instances? Dim strBO1Property As String = BO1.SomeVariable Dim strBO2Property As String = BO2.SomeVariable End Sub ' simple BusinessObject class Public Class BusinessObject Private _SomeVariable As String Public Property SomeVariable() As String Get Return _SomeVariable End Get Set(ByVal value As String) _SomeVariable = value End Set End Property End Class

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• ASP.NET MVC Head Verb and Selenium RC

  - by Rob

  Selenium (RC) is being used to test an ASP.NET 1.1 site. When we make a request via Selenium RC (and then in turn via Firefox or other configured browser) the http verb is "HEAD". We have several form action methods that have separate POST and GET methods decorated with AcceptVerbs(HttpVerbs.Get). These methods are returning a 404 and logging a "a public action method could not be found" error message. Questions: When writing separate Get/Post action methods what is the best practice for handling the Head verb? Should we always decorate with an AcceptVerbs(HttpVerbs.Get | HttpVerbs.Head)? The only time we've seen HEAD verbs is from Selenium and from some crawlers. We created robots.txt entries for the crawlers. Does anyone know why HEAD verbs are issued via Selenium (instead of an If-Modified-Since header)? Are there mainstream crawlers that use the HEAD verb? Does it affect SEO ranking to not have it?

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• How "duplicated" Java code is optimized by the JVM JIT compiler?

  - by Renan Vinícius Mozone

  I'm in charge of maintaining a JSP based application, running on IBM WebSphere 6.1 (IBM J9 JVM). All JSP pages have a static include reference and in this include file there is some static Java methods declared. They are included in all JSP pages to offer an "easy access" to those utility static methods. I know that this is a very bad way to work, and I'm working to change this. But, just for curiosity, and to support my effort in changing this, I'm wondering how these "duplicated" static methods are optimized by the JVM JIT compiler. They are optimized separately even having the exact same signature? Does the JVM JIT compiler "sees" that these methods are all identical an provides an "unified" JIT'ed code?

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• Set-Cookie error appearing in logs when deployed to google appengine

  - by Jesse

  I have been working towards converting one of our applications to be threadsafe. When testing on the local dev app server everything is working as expected. However, upon deployment of the application it seems that Cookies are not being written correctly? Within the logs there is an error with no stack trace: 2012-11-27 16:14:16.879 Set-Cookie: idd_SRP=Uyd7InRpbnlJZCI6ICJXNFdYQ1ZITSJ9JwpwMAou.Q6vNs9vGR-rmg0FkAa_P1PGBD94; expires=Wed, 28-Nov-2012 23:59:59 GMT; Path=/ Here is the block of code in question: # area of the code the emits the cookie cookie = Cookie.SimpleCookie() if not domain: domain = self.__domain self.__updateCookie(cookie, expires=expires, domain=domain) self.__updateSessionCookie(cookie, domain=domain) print cookie.output() Cookie helper methods: def __updateCookie(self, cookie, expires=None, domain=None): """ Takes a Cookie.SessionCookie instance an updates it with all of the private persistent cookie data, expiry and domain. @param cookie: a Cookie.SimpleCookie instance @param expires: a datetime.datetime instance to use for expiry @param domain: a string to use for the cookie domain """ cookieValue = AccountCookieManager.CookieHelper.toString(self.cookie) cookieName = str(AccountCookieManager.COOKIE_KEY % self.partner.pid) cookie[cookieName] = cookieValue cookie[cookieName]['path'] = '/' cookie[cookieName]['domain'] = domain if not expires: # set the expiry date to 1 day from now expires = datetime.date.today() + datetime.timedelta(days = 1) expiryDate = expires.strftime("%a, %d-%b-%Y 23:59:59 GMT") cookie[cookieName]['expires'] = expiryDate def __updateSessionCookie(self, cookie, domain=None): """ Takes a Cookie.SessionCookie instance an updates it with all of the private session cookie data and domain. @param cookie: a Cookie.SimpleCookie instance @param expires: a datetime.datetime instance to use for expiry @param domain: a string to use for the cookie domain """ cookieValue = AccountCookieManager.CookieHelper.toString(self.sessionCookie) cookieName = str(AccountCookieManager.SESSION_COOKIE_KEY % self.partner.pid) cookie[cookieName] = cookieValue cookie[cookieName]['path'] = '/' cookie[cookieName]['domain'] = domain Again, the libraries in use are: Python 2.7 Django 1.2 Any suggestion on what I can try?

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