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• SQL Azure Database Size Calculator

  - by kaleidoscope

  A neat trick on how to measure your database size in SQL Azure.  Here are the exact queries you can run to do it: Select Sum (reserved_page_count) * 8.0 / 1024 From sys.dm_db_partition_stats GO Select sys.objects.name, sum (reserved_page_count) * 8.0 / 1024 From sys.dm_db_partition_stats, sys.objects Where sys.dm_db_partition_stats.object_id = sys.objects.object_id Group by sys.objects.name The first one will give you the size of your database in MB and the second one will do the same, but break it out for each object in your database. http://www.azurejournal.com/2010/03/sql-azure-database-size-calculator/   Ritesh, D

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• Using T4 to generate Configuration classes

  - by Justin Hoffman

  I wanted to try to use T4 to read a web.config and generate all of the appSettings and connectionStrings as properties of a class.  I elected in this template only to output appSettings and connectionStrings but you can see it would be easily adapted for app specific settings, bindings etc.  This allows for quick access to config values as well as removing the potential for typo's when accessing values from the ConfigurationManager. One caveat: a developer would need to remember to run the .tt file after adding an entry to the web.config.  However, one would quickly notice when trying to access the property from the generated class (it wouldn't be there).  Additionally, there are other options as noted here. The first step was to create the .tt file.  Note that this is a basic example, it could be extended even further I'm sure.  In this example I just manually input the path to the web.config file. <#@ template debug="false" hostspecific="true" language="C#" #><#@ output extension=".cs" #><#@ assembly Name="System.Configuration" #><#@ assembly name="System.Xml" #><#@ assembly name="System.Xml.Linq" #><#@ assembly name="System.Net" #><#@ assembly name="System" #><#@ import namespace="System.Configuration" #><#@ import namespace="System.Xml" #><#@ import namespace="System.Net" #><#@ import namespace="Microsoft.VisualStudio.TextTemplating" #><#@ import namespace="System.Xml.Linq" #>using System;using System.Configuration;using System.Xml;using System.Xml.Linq;using System.Linq;namespace MyProject.Web { public partial class Configurator { <# var xDocument = XDocument.Load(@"G:\MySolution\MyProject\Web.config"); var results = xDocument.Descendants("appSettings"); const string key = "key"; const string name = "name"; foreach (var xElement in results.Descendants()) {#> public string <#= xElement.Attribute(key).Value#>{get {return ConfigurationManager.AppSettings[<#= string.Format("{0}{1}{2}","\"" , xElement.Attribute(key).Value, "\"")#>];}} <#}#> <# var connectionStrings = xDocument.Descendants("connectionStrings"); foreach(var connString in connectionStrings.Descendants()) {#> public string <#= connString.Attribute(name).Value#>{get {return ConfigurationManager.ConnectionStrings[<#= string.Format("{0}{1}{2}","\"" , connString.Attribute(name).Value, "\"")#>].ConnectionString;}} <#} #> }} The resulting .cs file: using System;using System.Configuration;using System.Xml;using System.Xml.Linq;using System.Linq;namespace MyProject.Web { public partial class Configurator { public string ClientValidationEnabled{get {return ConfigurationManager.AppSettings["ClientValidationEnabled"];}} public string UnobtrusiveJavaScriptEnabled{get {return ConfigurationManager.AppSettings["UnobtrusiveJavaScriptEnabled"];}} public string ServiceUri{get {return ConfigurationManager.AppSettings["ServiceUri"];}} public string TestConnection{get {return ConfigurationManager.ConnectionStrings["TestConnection"].ConnectionString;}} public string SecondTestConnection{get {return ConfigurationManager.ConnectionStrings["SecondTestConnection"].ConnectionString;}} }} Next, I extended the partial class for easy access to the Configuration. However, you could just use the generated class file itself. using System;using System.Linq;using System.Xml.Linq;namespace MyProject.Web{ public partial class Configurator { private static readonly Configurator Instance = new Configurator(); public static Configurator For { get { return Instance; } } }} Finally, in my example, I used the Configurator class like so: [TestMethod] public void Test_Web_Config() { var result = Configurator.For.ServiceUri; Assert.AreEqual(result, "http://localhost:30237/Service1/"); }

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• How can I simulate objects floating on water without a physics engine?

  - by user1075940

  In my game the water movement is done in a shader using Gerstner equations. The water movement looks realistic enough for a school project but I encounter serious problem when I wanted to do sailing on waves (similar to this). I managed to do collision with land by calculating quad's vertices and normals beneath ship, however same method can not be applied to water because XZ are displaced and Y is calculated in a shader :( How to approach this problem ? Is it possible to retrieve transformed grid from shader? Unfortunately no external physics libraries can be used.

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• How can I prevent seams from showing up on objects using lower mipmap levels?

  - by Shivan Dragon

  Disclaimer: kindly right click on the images and open them separately so that they're at full size, as there are fine details which don't show up otherwise. Thank you. I made a simple Blender model, it's a cylinder with the top cap removed: I've exported the UVs: Then imported them into Photoshop, and painted the inner area in yellow and the outer area in red. I made sure I cover well the UV lines: I then save the image and load it as texture on the model in Blender. Actually, I just reload it as the image where the UVs are exported, and change the viewport view mode to textured. When I look at the mesh up-close, there's yellow everywhere, everything seems fine: However, if I start zooming out, I start seeing red (literally and metaphorically) where the texture edges are: And the more I zoom, the more I see it: Same thing happends in Unity, though the effect seems less pronounced. Up close is fine and yellow: Zoom out and you see red at the seams: Now, obviously, for this simple example a workaround is to spread the yellow well outside the UV margins, and its fine from all distances. However this is an issue when you try making a complex texture that should tile seamlessly at the edges. In this situation I either make a few lines of pixels overlap (in which case it looks bad from upclose and ok from far away), or I leave them seamless and then I have those seams when seeing it from far away. So my question is, is there something I'm missing, or some extra thing I must do to have my texture look seamless from all distances?

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• Is it a good pattern that no objects should know more than what it needs to know?

  - by Jim Thio

  I am implementing a viewController class. The view controller class got NSNotification when the Grabbing class start or finish updating. I have 2 choices. I can make the grabbing class to provide a public read only property so all other classes can know whether it is still uploading. Or I can let view Controller to listen to 2 different events. Start updating and finish updating events. The truth is the viewController do need to know whether the grabbing class is still updating or not at any other time. So I am thinking of creating 2 events would be a better way to go. Actually, what do you think?

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• What types of objects are useful in SQL CLR?

  - by Greg Low

  I've had a number of people over the years ask about whether or not a particular type of object is a good candidate for SQL CLR integration. The rules that I normally apply are as follows: Database Object Transact-SQL Managed Code Scalar UDF Generally poor performance Good option when limited or no data-access Table-valued UDF Good option if data-related Good option when limited or no data-access Stored Procedure Good option Good option when external access is required or limited data access DML...(read more)

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• How do you handle objects that need custom behavior, and need to exist as an entity in the database?

  - by Scott Whitlock

  For a simple example, assume your application sends out notifications to users when various events happen. So in the database I might have the following tables: TABLE Event EventId uniqueidentifier EventName varchar TABLE User UserId uniqueidentifier Name varchar TABLE EventSubscription EventUserId EventId UserId The events themselves are generated by the program. So there are hard-coded points in the application where an event instance is generated, and it needs to notify all the subscribed users. So, the application itself doesn't edit the Event table, except during initial installation, and during an update where a new Event might be created. At some point, when an event is generated, the application needs to lookup the Event and get a list of Users. What's the best way to link the event in the source code to the event in the database? Option 1: Store the EventName in the program as a fixed constant, and look it up by name. Option 2: Store the EventId in the program as a static Guid, and look it up by ID. Extra Credit In other similar circumstances I may want to include custom behavior with the event type. That is, I'll want subclasses of my Event entity class with different behaviors, and when I lookup an event, I want it to return an instance of my subclass. For instance: class Event { public Guid Id { get; } public Guid EventName { get; } public ReadOnlyCollection<EventSubscription> EventSubscriptions { get; } public void NotifySubscribers() { foreach(var eventSubscription in EventSubscriptions) { eventSubscription.Notify(); } this.OnSubscribersNotified(); } public virtual void OnSubscribersNotified() {} } class WakingEvent : Event { private readonly IWaker waker; public WakingEvent(IWaker waker) { if(waker == null) throw new ArgumentNullException("waker"); this.waker = waker; } public override void OnSubscribersNotified() { this.waker.Wake(); base.OnSubscribersNotified(); } } So, that means I need to map WakingEvent to whatever key I'm using to look it up in the database. Let's say that's the EventId. Where do I store this relationship? Does it go in the event repository class? Should the WakingEvent know declare its own ID in a static member or method? ...and then, is this all backwards? If all events have a subclass, then instead of retrieving events by ID, should I be asking my repository for the WakingEvent like this: public T GetEvent<T>() where T : Event { ... // what goes here? ... } I can't be the first one to tackle this. What's the best practice?

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• Java heap space

  - by java_mouse

  In Java/JVM, why do we call the memory place where Java creates objects as "Heap"? Does it use the Heap Data Structure to create/remove/maintain the objects? As I read in the documentation of Heap data structure, the algorithm compares the objects with existing nodes and places them in such a way that Parent object is "greater" than the children. ( Or "lesser" in case of min heap). So in JVM, how are the objects compared against each other before placing them in the heap?

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• Where can I find free md2 models and .obj objects for a boxing game? [duplicate]

  - by omgzor

  This question is an exact duplicate of: What are good sites that provide free media resources for hobby game development? [closed] I'm creating a first person boxing game in Opengl as a school project and I want textures and models to apply to it. A look like Wii Sport's Boxing is what I'm aiming for. Something like this (but, you know, free)

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• Algorithms for pairing a rating system to an assignment queue

  - by blunders

  Attempting to research how to allow a group of people to effectively rank a set of objects (each group member will have contributed one object to the group), and then assign each member an object that's not their own based on: Their ratings of the objects, Their objects rating, and The object remaining to be assigned. Idea is to attempt to assign objects to people based on the groups rating of their contribution to the group relative to other member's contribution, the the personal preferences expressed via the ratings. Any suggestions for: Further research, Refining the statement of the problem/solution, or A solution.

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• What if globals make sense?

  - by Greg

  I've got a value that many objects need. For example, a financial application with different investments as objects, and most of them need the current interest rate. I was hoping to encapsulate my "financial environment" as an object, with the interest rate as a property. But, sibling objects that need that value can't get to it. So how do I share values among many objects without over-coupling my design? Obviously I'm thinking about this wrong.

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• Why are only some of my objects being rendered?

  - by BleedObsidian

  Every time I create a new asteroid the previous one is no longer rendered? I did some debugging and printed out the size of Array-List 'Small' and when a new asteroid is created it doesn't go down, so the thread is still there it's just not being rendered, Why? StatePlay: package me.bleedobsidian.astroidjump; import org.newdawn.slick.GameContainer; import org.newdawn.slick.Graphics; import org.newdawn.slick.SlickException; import org.newdawn.slick.state.BasicGameState; import org.newdawn.slick.state.StateBasedGame; public class StatePlay extends BasicGameState { int stateID = 10; Player player; Asteroids asteroids; StatePlay(int stateID) { this.stateID = stateID; } @Override public int getID() { return stateID; } @Override public void init(GameContainer gc, StateBasedGame sbg) throws SlickException { ResManager.loadImages(); player = new Player(); asteroids = new Asteroids(); } @Override public void render(GameContainer gc, StateBasedGame sbg, Graphics g) throws SlickException { g.setAntiAlias(true); player.render(g); asteroids.render(g); g.drawString("Asteroids: " + Asteroids.small.size(), 10, 25); } @Override public void update(GameContainer gc, StateBasedGame sbg, int delta) throws SlickException { player.update(gc, delta); asteroids.update(delta); } } Asteroids: package me.bleedobsidian.astroidjump; import java.util.ArrayList; import java.util.Timer; import org.newdawn.slick.Graphics; import org.newdawn.slick.Image; import org.newdawn.slick.SpriteSheet; public class Asteroids { public static ArrayList<Asteroid_Small> small = new ArrayList<Asteroid_Small>(); static SpriteSheet small_sprites = new SpriteSheet(ResManager.asteroids_small_ss, 32, 32); static Image small_1 = small_sprites.getSubImage(0, 0); static Image small_2 = small_sprites.getSubImage(1, 0); static Image small_3 = small_sprites.getSubImage(2, 0); static Image small_4 = small_sprites.getSubImage(3, 0); static boolean asteroids = true; static int diff = 0; Asteroids() { Task_Asteroids TaskA = new Task_Asteroids(); Timer timer = new Timer("Asteroids"); if(diff == 0) { timer.schedule(TaskA, 0, 4000); } else if(diff == 1) { timer.schedule(TaskA, 0, 3000); } } public static Image chooseSmallImage(int i) { if(i == 0) { return small_1; } else if(i == 1) { return small_2; } else if(i == 2) { return small_3; } else if(i == 3) { return small_4; } else { return small_1; } } public static void level_manager(float x) { if(x < 1000) { diff = 0; } else if(x < 2000) { diff = 1; } else if(x < 3000) { diff = 2; } else if(x < 5000) { diff = 3; } else if(x < 10000) { diff = 4; } else { diff = 5; } } public void update(int delta) { for(int s = 0; s < small.size(); s++) { Asteroid_Small as = small.get(s); as.update(delta); } } public void render(Graphics g) { for(int s = 0; s < small.size(); s++) { Asteroid_Small as = small.get(s); as.render(g); } } public static void setAsteroids(boolean tf) { asteroids = tf; } } Asteroid_Small: package me.bleedobsidian.astroidjump; import org.newdawn.slick.Graphics; import org.newdawn.slick.Image; public class Asteroid_Small { private static Image me; private static float x = 0; private static float y = 0; private static float speed = 0; private static float rotation = 0; private static float rotation_speed = 0; Asteroid_Small(Image i, float x, float y, float rs, float sp) { me = i; Asteroid_Small.x = x; Asteroid_Small.y = y; Asteroid_Small.rotation_speed = rs; Asteroid_Small.speed = sp; } public void update(int delta) { x -= speed * delta; rotation += rotation_speed * delta; me.setRotation(rotation); } public void render(Graphics g) { g.drawImage(me, x, y); } } Task_Asteroid: package me.bleedobsidian.astroidjump; import java.util.TimerTask; public class Task_Asteroids extends TimerTask { public void run() { if(Asteroids.diff == 0) { int randImage = (int) (Math.random() * 4); int randHeight = (int) (Math.random() * 480); Asteroids.small.add(new Asteroid_Small(Asteroids.chooseSmallImage(randImage), Player.x + 960, randHeight, 0.05f, 0.04f)); } } }

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• Why RenderTarget2D overwrites other objects when trying to put some text in a model?

  - by cad

  I am trying to draw an object composited by two cubes (A & B) (one on top of the other, but for now I have them a little bit more open). I am able to do it and this is the result. (Cube A is the blue and Cube B is the one with brown text that comes from a png texture) But I want to have any text as parameter in the cube B. I have tried what @alecnash suggested in his question, but for some reason when I try to draw cube B, cube A dissapears and everything turns purple. This is my draw code: public void Draw(GraphicsDevice graphicsDevice, SpriteBatch spriteBatch, Matrix viewMatrix, Matrix projectionMatrix) { graphicsDevice.BlendState = BlendState.Opaque; graphicsDevice.DepthStencilState = DepthStencilState.Default; graphicsDevice.RasterizerState = RasterizerState.CullCounterClockwise; graphicsDevice.SamplerStates[0] = SamplerState.LinearClamp; // CUBE A basicEffect.View = viewMatrix; basicEffect.Projection = projectionMatrix; basicEffect.World = Matrix.CreateTranslation(ModelPosition); basicEffect.VertexColorEnabled = true; foreach (EffectPass pass in basicEffect.CurrentTechnique.Passes) { pass.Apply(); drawCUBE_TOP(graphicsDevice); drawCUBE_Floor(graphicsDevice); DrawFullSquareStripesFront(graphicsDevice, _numStrips, Color.Red, Color.Blue, _levelPercentage); DrawFullSquareStripesLeft(graphicsDevice, _numStrips, Color.Red, Color.Blue, _levelPercentage); DrawFullSquareStripesRight(graphicsDevice, _numStrips, Color.Red, Color.Blue, _levelPercentage); DrawFullSquareStripesBack(graphicsDevice, _numStrips, Color.Red, Color.Blue, _levelPercentage); } // CUBE B // Set the World matrix which defines the position of the cube texturedCubeEffect.World = Matrix.CreateTranslation(ModelPosition); // Set the View matrix which defines the camera and what it's looking at texturedCubeEffect.View = viewMatrix; // Set the Projection matrix which defines how we see the scene (Field of view) texturedCubeEffect.Projection = projectionMatrix; // Enable textures on the Cube Effect. this is necessary to texture the model texturedCubeEffect.TextureEnabled = true; Texture2D a = SpriteFontTextToTexture(graphicsDevice, spriteBatch, arialFont, "TEST ", Color.Black, Color.GhostWhite); texturedCubeEffect.Texture = a; //texturedCubeEffect.Texture = cubeTexture; // Enable some pretty lights texturedCubeEffect.EnableDefaultLighting(); // apply the effect and render the cube foreach (EffectPass pass in texturedCubeEffect.CurrentTechnique.Passes) { pass.Apply(); cubeToDraw.RenderToDevice(graphicsDevice); } } private Texture2D SpriteFontTextToTexture(GraphicsDevice graphicsDevice, SpriteBatch spriteBatch, SpriteFont font, string text, Color backgroundColor, Color textColor) { Vector2 Size = font.MeasureString(text); RenderTarget2D renderTarget = new RenderTarget2D(graphicsDevice, (int)Size.X, (int)Size.Y); graphicsDevice.SetRenderTarget(renderTarget); graphicsDevice.Clear(Color.Transparent); spriteBatch.Begin(); //have to redo the ColorTexture //spriteBatch.Draw(ColorTexture.Create(graphicsDevice, 1024, 1024, backgroundColor), Vector2.Zero, Color.White); spriteBatch.DrawString(font, text, Vector2.Zero, textColor); spriteBatch.End(); graphicsDevice.SetRenderTarget(null); return renderTarget; } The way I generate texture with dynamic text is: Texture2D a = SpriteFontTextToTexture(graphicsDevice, spriteBatch, arialFont, "TEST ", Color.Black, Color.GhostWhite); After commenting several parts to see what caused the problem, it seems to be located in this line graphicsDevice.SetRenderTarget(renderTarget);

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• Should this code/logic be included in Business Objects class or a separate class?

  - by aspdotnetuser

  I have created a small application which has a three tier architecture and I have business object classes to represent entities such as User, Orders, UserType etc. In these classes I have methods that are executed when the Constuctor method of, for example, User is called. These methods perform calculations and generate details that setup data for attributes that are part of each User object. Here is the structure for the project in Visual Studio: Here is some code from the business object class User.cs: Public Class User { public string Name { get; set; } public int RandomNumber { get; set; } etc public User { Name = GetName(); RandomNumber = GetRandomNumber(); } public string GetName() { .... return name; } public int GetRandomNumber() { ... return randomNumber; } } Should this logic be included in the Business Object classes or should it be included in a Utilities class of some kind? Or in the business rules?

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• How to simulate objects floating on water without a physics engine?

  - by user1075940

  In my game the water movement is done in a shader using Gerstner equations. The water movement looks realistic enough for a school project but I encounter serious problem when I wanted to do sailing on waves (similar to this). I managed to do collision with land by calculating quad's vertices and normals beneath ship, however same method can not be applied to water because XZ are displaced and Y is calculated in a shader :( How to approach this problem ? Is it possible to retrieve transformed grid from shader? Unfortunately no external physics libraries can be used.

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• What techniques can I use to render very large numbers of objects more efficiently in OpenGL?

  - by Luke

  You can think of my application as drawing a very large ball-and-stick diagram (or graph). At times, this graph can get very large, where the number of elements even outnumbers the pixels on the screen. Currently I am simply passing all of my textures (as GL_POINTS) and lines to the graphics card using VBO's. When the number of elements outnumbers the number of pixels, is this the most efficient way to do this? Or should I do some calculations on the CPU side before handing everything over to the GPU? If it matters, I do use GL_DEPTH_TEST and GL_ALPHA_TEST. I do some alpha blending, but probably not enough to make a huge performance difference. My scene can be static at times, but the user has control over a typical arc-ball camera and can pan, rotate, or zoom. It is during these operations that performance degradation is noticeable.

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• SOLVED: The type or namespace name 'Linq' does not exist in the namespace 'System' - are you missing

  This problem has been cropping up a lot recently - projects will complain of missing namespace's when I open them up and attempt to compile the first time. If this has happened to you then read on for a simple fix. Scenario I don't know if this one is a bug in Visual Studio 2010 (Beta 2 and RC1) or something else but recently I have noticed this error cropping up more and more. When I open an existing project it might fail to compile. I have also noticed it happen when I have downloaded a fresh...Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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• What's a good way to store a series of interconnected pipe and tank objects?

  - by mars

  I am working on a puzzle game with a 6 by 6 grid of storage tanks that are connected to up to 4 tanks adjacent to them via pipes. The gameplay is concerned with combining what's in a tank with an adjacent tank via the pipe than interconnects them. Right now I store the tanks in a 6x6 array, vertical pipes in a 5x6 array, and horizontal pipes in a 6x5 array. Each tank has a reference to the object that contains both tanks and pipes and when a pipe needs to be animated filling with liquid, the selected tank just calls a method on the container object telling it to animate the pipes it is connected to (subtract 1 from row or column to find connected pipes). This feels like the wrong way of doing it, as I've also considered just giving each tank references to the pipes connected to it to access directly.

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• MS Access 2007 doesn't allow to group form objects anymore like in 2003 ?

  - by asksuperuser

  It's a long time I haven't looked at MS Access but I clearly remembered it was possible to select multiple objects (lines, textbox, etc.) and type Ctrl + G to group them. In Access 2007 I can't make it work and I can't find any context menu to do so. Has this feature been erased by MS ?

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• How can you procedurally place objects in a non-gridded game?

  - by nickbadal

  This is a follow-up question to this question. I mistakenly worded the question, but got a good answer before I could correct myself, so I didn't want to delete it. Sorry! Now that I know that it is possible, I'd like to implement procedural world generation, but I don't want it to look gridded or blocky, where everything is obviously placed on an integer grid. I know that you can do this in gridded worlds by inputting a square's x and y into a noise function, or similar, but how can I generate a more natural looking object placement using procedural methods? This is in the context of an adventure game, if it matters.

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• Static vs. dynamic memory allocation - lots of constant objects, only small part of them used at runtime

  - by k29

  Here are two options: Option 1: enum QuizCategory { CATEGORY_1(new MyCollection<Question>() .add(Question.QUESTION_A) .add(Question.QUESTION_B) .add...), CATEGORY_2(new MyCollection<Question>() .add(Question.QUESTION_B) .add(Question.QUESTION_C) .add...), ... ; public MyCollection<Question> collection; private QuizCategory(MyCollection<Question> collection) { this.collection = collection; } public Question getRandom() { return collection.getRandomQuestion(); } } Option 2: enum QuizCategory2 { CATEGORY_1 { @Override protected MyCollection<Question> populateWithQuestions() { return new MyCollection<Question>() .add(Question.QUESTION_A) .add(Question.QUESTION_B) .add...; } }, CATEGORY_2 { @Override protected MyCollection<Question> populateWithQuestions() { return new MyCollection<Question>() .add(Question.QUESTION_B) .add(Question.QUESTION_C) .add...; } }; public Question getRandom() { MyCollection<Question> collection = populateWithQuestions(); return collection.getRandomQuestion(); } protected abstract MyCollection<Question> populateWithQuestions(); } There will be around 1000 categories, each containing 10 - 300 questions (100 on average). At runtime typically only 10 categories and 30 questions will be used. Each question is itself an enum constant (with its fields and methods). I'm trying to decide between those two options in the mobile application context. I haven't done any measurements since I have yet to write the questions and would like to gather more information before committing to one or another option. As far as I understand: (a) Option 1 will perform better since there will be no need to populate the collection and then garbage-collect the questions; (b) Option 1 will require extra memory: 1000 categories x 100 questions x 4 bytes for each reference = 400 Kb, which is not significant. So I'm leaning to Option 1, but just wondered if I'm correct in my assumptions and not missing something important? Perhaps someone has faced a similar dilemma? Or perhaps it doesn't actually matter that much?

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• Did Bjarne Stroustrup create the terms constructor/destructor when talking about objects?

  - by user104971

  I was watching this keynote and Bjarne Stroustrup (Creator of C++) claims that he hadn't yet invented the words constructor and destructor yet when he was giving an example of RAII. http://www.youtube.com/watch?v=IYBLXBJr0HU I know the concept of construction and destruction has been around a lot longer (even in C, a function that allocates and returns a struct and then a function that frees it etc.), but was Bjarne really the first to invent the terms?

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• Can I retrieve objects from a complex query that limits results to fields from a single table?

  - by Sean Redmond

  I have a model whose rows I always want to sort based on the values in another associated model and I was thinking that the way to implement this would be to use set_dataset in the model. This is causing query results to be returned as hashes rather than objects, though, so none of the methods from the class can be used when iterating over the dataset. I basically have two classes class SortFields < Sequel::Model(:sort_fields) set_primary_key :objectid end class Items < Sequel::Model(:items) set_primary_key :objectid one_to_one :sort_fields, :class => SortFields, :key => :objectid end Some backstory: the data is imported from a legacy system into mysql. The values in sort_fields are calculated from multiple other associated tables (some one-to-many, some many-to-many) according to some complicated rules. The likely solution will be to just add the values in sort_fields to items (I want to keep the imported data separate from the calculated data, but I don't have to). First, though, I just want to understand how far you can go with a dataset and still get objects rather than hashes. If I set the dataset to sort on a field in items like so class Items < Sequel::Model(:items) set_primary_key :objectid one_to_one :sort_fields, :class => SortFields, :key => :objectid set_dataset(order(:sortnumber)) end then the expected clause is added to the generated SQL, e.g.: >> Items.limit(1).sql => "SELECT * FROM `items` ORDER BY `sortnumber` LIMIT 1" and queries still return objects: >> Items.limit(1).first.class => Items If I order it by the associated fields though... class Items < Sequel::Model(:items) set_primary_key :objectid one_to_one :sort_fields, :class => SortFields, :key => :objectid set_dataset( eager_graph(:sort_fields). order(:sort1, :sort2, :sort3) ) end ...I get hashes ?> Items.limit(1).first.class => Hash My first thought was that this happens because all fields from sort_fields are included in the results and maybe if selected only the fields from items I would get Items objects again: class Items < Sequel::Model(:items) set_primary_key :objectid one_to_one :sort_fields, :class => SortFields, :key => :objectid set_dataset( eager_graph(:sort_fields). select(:items.*). order(:sort1, :sort2, :sort3) ) end The generated SQL is what I would expect: >> Items.limit(1).sql => "SELECT `items`.* FROM `items` LEFT OUTER JOIN `sort_fields` ON (`sort_fields`.`objectid` = `items`.`objectid`) ORDER BY `sort1`, `sort2`, `sort3` LIMIT 1" It returns the same rows as the set_dataset(order(:sortnumber)) version but it still doesn't work: >> Items.limit(1).first.class => Hash Before I add the sort fields to the items table so that they can all live happily in the same model, is there a way to tell Sequel to return on object when it wants to return a hash?

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• ASP.NET exception gives irrelevant stack trace on YSOD, very challenging!

  - by pootow

  Here is the YSOD: Timeout expired. The timeout period elapsed prior to completion of the operation or the server is not responding. Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code. Exception Details: System.Data.SqlClient.SqlException: Timeout expired. The timeout period elapsed prior to completion of the operation or the server is not responding. Source Error: An unhandled exception was generated during the execution of the current web request. Information regarding the origin and location of the exception can be identified using the exception stack trace below. Stack Trace: [SqlException (0x80131904): Timeout expired. The timeout period elapsed prior to completion of the operation or the server is not responding.] System.Data.ProviderBase.DbConnectionPool.GetConnection(DbConnection owningObject) +428 System.Data.ProviderBase.DbConnectionFactory.GetConnection(DbConnection owningConnection) +65 System.Data.ProviderBase.DbConnectionClosed.OpenConnection(DbConnection outerConnection, DbConnectionFactory connectionFactory) +117 System.Data.SqlClient.SqlConnection.Open() +122 ECommerce.PMethod.Sql.SqlConns.Open() +78 ECommerce.PMethod.Sql.SqlConns..ctor() +120 ECommerce.login.DatasInfo.Proc.UserCenter.IsLogin(String UserGUID, Int32 UserID) +49 ECommerce.login.Rules.Users.UserLogin.isLogin() +44 Config.isUserLogined() +5 Shopping_Shopping.Page_Load(Object sender, EventArgs e) +10 System.Web.Util.CalliHelper.EventArgFunctionCaller(IntPtr fp, Object o, Object t, EventArgs e) +14 System.Web.Util.CalliEventHandlerDelegateProxy.Callback(Object sender, EventArgs e) +35 System.Web.UI.Control.OnLoad(EventArgs e) +99 System.Web.UI.Control.LoadRecursive() +50 System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +627 [TypeInitializationException: The type initializer for 'ECommerce.ERP.DAL.DBConn' threw an exception.] ECommerce.ERP.DAL.DBConn.get_ConnString() +0 [ObjectDefinitionStoreException: Factory method 'System.String get_ConnString()' threw an Exception.] Spring.Objects.Factory.Support.SimpleInstantiationStrategy.Instantiate(RootObjectDefinition definition, String name, IObjectFactory factory, MethodInfo factoryMethod, Object[] arguments) +257 Spring.Objects.Factory.Support.ConstructorResolver.InstantiateUsingFactoryMethod(String name, RootObjectDefinition definition, Object[] arguments) +624 Spring.Objects.Factory.Support.AbstractAutowireCapableObjectFactory.InstantiateUsingFactoryMethod(String name, RootObjectDefinition definition, Object[] arguments) +60 Spring.Objects.Factory.Support.AbstractAutowireCapableObjectFactory.CreateObjectInstance(String objectName, RootObjectDefinition objectDefinition, Object[] arguments) +56 Spring.Objects.Factory.Support.AbstractAutowireCapableObjectFactory.InstantiateObject(String name, RootObjectDefinition definition, Object[] arguments, Boolean allowEagerCaching, Boolean suppressConfigure) +436 [ObjectCreationException: Error thrown by a dependency of object 'styleService' defined in 'assembly [ECommerce.Services.Impl, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null], resource [ECommerce.Services.Impl.AppContext.xml] line 56' : Initialization of object failed : Factory method 'System.String get_ConnString()' threw an Exception. while resolving 'constructor argument with name promotionservice' to 'promotionService' defined in 'assembly [ECommerce.Services.Impl, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null], resource [ECommerce.Services.Impl.AppContext.xml] line 31' while resolving 'constructor argument with name domainservice' to 'promotionDomainService' defined in 'assembly [ECommerce.Domain, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null], resource [ECommerce.Domain.AppContext.xml] line 20' while resolving 'constructor argument with name promotionrepos' to 'promotionRepos' defined in 'assembly [ECommerce.Data.AdoNet, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null], resource [ECommerce.Data.AdoNet.AppContext.xml] line 34' while resolving 'constructor argument with name connstr' to 'ECommerce.ERP.DAL.DBConn#389F399' defined in 'assembly [ECommerce.Data.AdoNet, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null], resource [ECommerce.Data.AdoNet.AppContext.xml] line 34'] Spring.Objects.Factory.Support.ObjectDefinitionValueResolver.ResolveReference(IObjectDefinition definition, String name, String argumentName, RuntimeObjectReference reference) +394 Spring.Objects.Factory.Support.ObjectDefinitionValueResolver.ResolvePropertyValue(String name, IObjectDefinition definition, String argumentName, Object argumentValue) +312 Spring.Objects.Factory.Support.ObjectDefinitionValueResolver.ResolveValueIfNecessary(String name, IObjectDefinition definition, String argumentName, Object argumentValue) +17 Spring.Objects.Factory.Support.ConstructorResolver.ResolveConstructorArguments(String objectName, RootObjectDefinition definition, ObjectWrapper wrapper, ConstructorArgumentValues cargs, ConstructorArgumentValues resolvedValues) +993 Spring.Objects.Factory.Support.ConstructorResolver.AutowireConstructor(String objectName, RootObjectDefinition rod, ConstructorInfo[] chosenCtors, Object[] explicitArgs) +171 Spring.Objects.Factory.Support.AbstractAutowireCapableObjectFactory.AutowireConstructor(String name, RootObjectDefinition definition, ConstructorInfo[] ctors, Object[] explicitArgs) +65 Spring.Objects.Factory.Support.AbstractAutowireCapableObjectFactory.CreateObjectInstance(String objectName, RootObjectDefinition objectDefinition, Object[] arguments) +161 Spring.Objects.Factory.Support.AbstractAutowireCapableObjectFactory.InstantiateObject(String name, RootObjectDefinition definition, Object[] arguments, Boolean allowEagerCaching, Boolean suppressConfigure) +636 Spring.Objects.Factory.Support.AbstractObjectFactory.CreateAndCacheSingletonInstance(String objectName, RootObjectDefinition objectDefinition, Object[] arguments) +174 Spring.Objects.Factory.Support.WebObjectFactory.CreateAndCacheSingletonInstance(String objectName, RootObjectDefinition objectDefinition, Object[] arguments) +150 Spring.Objects.Factory.Support.AbstractObjectFactory.GetObjectInternal(String name, Type requiredType, Object[] arguments, Boolean suppressConfigure) +990 Spring.Objects.Factory.Support.AbstractObjectFactory.GetObject(String name) +10 Spring.Context.Support.AbstractApplicationContext.GetObject(String name) +20 ECommerce.Common.ServiceLocator.GetService() +334 ECommerce.Mvc.Controllers.StylesController..ctor() +72 [TargetInvocationException: Exception has been thrown by the target of an invocation.] System.RuntimeTypeHandle.CreateInstance(RuntimeType type, Boolean publicOnly, Boolean noCheck, Boolean& canBeCached, RuntimeMethodHandle& ctor, Boolean& bNeedSecurityCheck) +0 System.RuntimeType.CreateInstanceSlow(Boolean publicOnly, Boolean fillCache) +86 System.RuntimeType.CreateInstanceImpl(Boolean publicOnly, Boolean skipVisibilityChecks, Boolean fillCache) +230 System.Activator.CreateInstance(Type type, Boolean nonPublic) +67 System.Web.Mvc.DefaultControllerFactory.GetControllerInstance(RequestContext requestContext, Type controllerType) +80 [InvalidOperationException: An error occurred when trying to create a controller of type 'ECommerce.Mvc.Controllers.StylesController'. Make sure that the controller has a parameterless public constructor.] System.Web.Mvc.DefaultControllerFactory.GetControllerInstance(RequestContext requestContext, Type controllerType) +190 System.Web.Mvc.DefaultControllerFactory.CreateController(RequestContext requestContext, String controllerName) +68 System.Web.Mvc.MvcHandler.ProcessRequestInit(HttpContextBase httpContext, IController& controller, IControllerFactory& factory) +118 System.Web.Mvc.MvcHandler.BeginProcessRequest(HttpContextBase httpContext, AsyncCallback callback, Object state) +46 System.Web.Mvc.MvcHandler.BeginProcessRequest(HttpContext httpContext, AsyncCallback callback, Object state) +63 System.Web.Mvc.MvcHandler.System.Web.IHttpAsyncHandler.BeginProcessRequest(HttpContext context, AsyncCallback cb, Object extraData) +13 System.Web.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() +8677954 System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) +155 Version Information: Microsoft .NET Framework Version:2.0.50727.3082; ASP.NET Version:2.0.50727.3082 Question is: the first stack trace is irrelevant to others, what happened? Any ideas? Let me make this more clear: a MVC page uses the spring part trying to load a lazy-init service which constructor wants a connection string through a static property like this: <object id="promotionRepos" type="ECommerce.Data.AdoNet.Promotions.PromotionRepos, ECommerce.Data.AdoNet" lazy-init="true"> <constructor-arg name="provider"> <null /> </constructor-arg> <constructor-arg name="connStr"> <object type="ECommerce.ERP.DAL.DBConn, ECommerce.ERP.DAL" factory-method="get_ConnString" /> </constructor-arg> <property name="RefreshInterval" value="00:00:10" /> </object> the timeout part is some what irrelevent to all others. see this in the first exception: Shopping_Shopping.Page_Load(Object sender, EventArgs e) +10 it's another page at all. And also, ECommerce.PMethod.Sql.SqlConns.Open() uses its own connection string, not the one loaded by spring, it's different module from diffrent team. And I am sure the connection string is correct. And, this ysod cames up randomly. Sometimes nothing is wrong, and sometimes, it appears. I thought there could be something wrong with my database or the network/firewall, I will check it later, but now I want understand this tricky stack trace.

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• Parallelism in .NET – Part 8, PLINQ’s ForAll Method

  - by Reed

  Parallel LINQ extends LINQ to Objects, and is typically very similar.  However, as I previously discussed, there are some differences.  Although the standard way to handle simple Data Parellelism is via Parallel.ForEach, it’s possible to do the same thing via PLINQ. PLINQ adds a new method unavailable in standard LINQ which provides new functionality… LINQ is designed to provide a much simpler way of handling querying, including filtering, ordering, grouping, and many other benefits.  Reading the description in LINQ to Objects on MSDN, it becomes clear that the thinking behind LINQ deals with retrieval of data.  LINQ works by adding a functional programming style on top of .NET, allowing us to express filters in terms of predicate functions, for example. PLINQ is, generally, very similar.  Typically, when using PLINQ, we write declarative statements to filter a dataset or perform an aggregation.  However, PLINQ adds one new method, which provides a very different purpose: ForAll. The ForAll method is defined on ParallelEnumerable, and will work upon any ParallelQuery<T>.  Unlike the sequence operators in LINQ and PLINQ, ForAll is intended to cause side effects.  It does not filter a collection, but rather invokes an action on each element of the collection. At first glance, this seems like a bad idea.  For example, Eric Lippert clearly explained two philosophical objections to providing an IEnumerable<T>.ForEach extension method, one of which still applies when parallelized.  The sole purpose of this method is to cause side effects, and as such, I agree that the ForAll method “violates the functional programming principles that all the other sequence operators are based upon”, in exactly the same manner an IEnumerable<T>.ForEach extension method would violate these principles.  Eric Lippert’s second reason for disliking a ForEach extension method does not necessarily apply to ForAll – replacing ForAll with a call to Parallel.ForEach has the same closure semantics, so there is no loss there. Although ForAll may have philosophical issues, there is a pragmatic reason to include this method.  Without ForAll, we would take a fairly serious performance hit in many situations.  Often, we need to perform some filtering or grouping, then perform an action using the results of our filter.  Using a standard foreach statement to perform our action would avoid this philosophical issue: // Filter our collection var filteredItems = collection.AsParallel().Where( i => i.SomePredicate() ); // Now perform an action foreach (var item in filteredItems) { // These will now run serially item.DoSomething(); } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } This would cause a loss in performance, since we lose any parallelism in place, and cause all of our actions to be run serially. We could easily use a Parallel.ForEach instead, which adds parallelism to the actions: // Filter our collection var filteredItems = collection.AsParallel().Where( i => i.SomePredicate() ); // Now perform an action once the filter completes Parallel.ForEach(filteredItems, item => { // These will now run in parallel item.DoSomething(); }); This is a noticeable improvement, since both our filtering and our actions run parallelized.  However, there is still a large bottleneck in place here.  The problem lies with my comment “perform an action once the filter completes”.  Here, we’re parallelizing the filter, then collecting all of the results, blocking until the filter completes.  Once the filtering of every element is completed, we then repartition the results of the filter, reschedule into multiple threads, and perform the action on each element.  By moving this into two separate statements, we potentially double our parallelization overhead, since we’re forcing the work to be partitioned and scheduled twice as many times. This is where the pragmatism comes into play.  By violating our functional principles, we gain the ability to avoid the overhead and cost of rescheduling the work: // Perform an action on the results of our filter collection .AsParallel() .Where( i => i.SomePredicate() ) .ForAll( i => i.DoSomething() ); The ability to avoid the scheduling overhead is a compelling reason to use ForAll.  This really goes back to one of the key points I discussed in data parallelism: Partition your problem in a way to place the most work possible into each task.  Here, this means leaving the statement attached to the expression, even though it causes side effects and is not standard usage for LINQ. This leads to my one guideline for using ForAll: The ForAll extension method should only be used to process the results of a parallel query, as returned by a PLINQ expression. Any other usage scenario should use Parallel.ForEach, instead.

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