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  • Do I suffer from encapsulation overuse?

    - by Florenc
    I have noticed something in my code in various projects that seems like code smell to me and something bad to do, but I can't deal with it. While trying to write "clean code" I tend to over-use private methods in order to make my code easier to read. The problem is that the code is indeed cleaner but it's also more difficult to test (yeah I know I can test private methods...) and in general it seems a bad habit to me. Here's an example of a class that reads some data from a .csv file and returns a group of customers (another object with various fields and attributes). public class GroupOfCustomersImporter { //... Call fields .... public GroupOfCustomersImporter(String filePath) { this.filePath = filePath; customers = new HashSet<Customer>(); createCSVReader(); read(); constructTTRP_Instance(); } private void createCSVReader() { //.... } private void read() { //.... Reades the file and initializes the class attributes } private void readFirstLine(String[] inputLine) { //.... Method used by the read() method } private void readSecondLine(String[] inputLine) { //.... Method used by the read() method } private void readCustomerLine(String[] inputLine) { //.... Method used by the read() method } private void constructGroupOfCustomers() { //this.groupOfCustomers = new GroupOfCustomers(**attributes of the class**); } public GroupOfCustomers getConstructedGroupOfCustomers() { return this.GroupOfCustomers; } } As you can see the class has only a constructor which calls some private methods to get the job done, I know that's not a good practice not a good practice in general but I prefer to encapsulate all the functionality in the class instead of making the methods public in which case a client should work this way: GroupOfCustomersImporter importer = new GroupOfCustomersImporter(filepath) importer.createCSVReader(); read(); GroupOfCustomer group = constructGoupOfCustomerInstance(); I prefer this because I don't want to put useless lines of code in the client's side code bothering the client class with implementation details. So, Is this actually a bad habit? If yes, how can I avoid it? Please note that the above is just a simple example. Imagine the same situation happening in something a little bit more complex.

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  • Gravity stops when side-collision detected

    - by Adrian Marszalek
    Please, look at this GIF: The label on the animation says "Move button is pressed, then released". And you can see when it's pressed (and player's getCenterY() is above wall getCenterY()), gravity doesn't work. I'm trying to fix it since yesterday, but I can't. All methods are called from game loop. public void move() { if (left) { switch (game.currentLevel()) { case 1: for (int i = 0; i < game.lvl1.getX().length; i++) game.lvl1.getX()[i] += game.physic.xVel; break; } } else if (right) { switch (game.currentLevel()) { case 1: for (int i = 0; i < game.lvl1.getX().length; i++) game.lvl1.getX()[i] -= game.physic.xVel; break; } } } int manCenterX, manCenterY, boxCenterX, boxCenterY; //gravity stop public void checkCollision() { for (int i = 0; i < game.lvl1.getX().length; i++) { manCenterX = (int) game.man.getBounds().getCenterX(); manCenterY = (int) game.man.getBounds().getCenterY(); if (game.man.getBounds().intersects(game.lvl1.getBounds(i))) { boxCenterX = (int) game.lvl1.getBounds(i).getCenterX(); boxCenterY = (int) game.lvl1.getBounds(i).getCenterY(); if (manCenterY - boxCenterY > 0 || manCenterY - boxCenterY < 0) { game.man.setyPos(-2f); game.man.isFalling = false; } } } } //left side of walls public void colliLeft() { for (int i = 0; i < game.lvl1.getX().length; i++) { if (game.man.getBounds().intersects(game.lvl1.getBounds(i))) { if (manCenterX - boxCenterX < 0) { for (int i1 = 0; i1 < game.lvl1.getX().length; i1++) { game.lvl1.getX()[i1] += game.physic.xVel; game.man.isFalling = true; } } } } } //right side of walls public void colliRight() { for (int i = 0; i < game.lvl1.getX().length; i++) { if (game.man.getBounds().intersects(game.lvl1.getBounds(i))) { if (manCenterX - boxCenterX > 0) { for (int i1 = 0; i1 < game.lvl1.getX().length; i1++) { game.lvl1.getX()[i1] += -game.physic.xVel; game.man.isFalling = true; } } } } } public void gravity() { game.man.setyPos(yVel); } //not called from gameloop: public void setyPos(float yPos) { this.yPos += yPos; }

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  • ASP.NET Web API and Simple Value Parameters from POSTed data

    - by Rick Strahl
    In testing out various features of Web API I've found a few oddities in the way that the serialization is handled. These are probably not super common but they may throw you for a loop. Here's what I found. Simple Parameters from Xml or JSON Content Web API makes it very easy to create action methods that accept parameters that are automatically parsed from XML or JSON request bodies. For example, you can send a JavaScript JSON object to the server and Web API happily deserializes it for you. This works just fine:public string ReturnAlbumInfo(Album album) { return album.AlbumName + " (" + album.YearReleased.ToString() + ")"; } However, if you have methods that accept simple parameter types like strings, dates, number etc., those methods don't receive their parameters from XML or JSON body by default and you may end up with failures. Take the following two very simple methods:public string ReturnString(string message) { return message; } public HttpResponseMessage ReturnDateTime(DateTime time) { return Request.CreateResponse<DateTime>(HttpStatusCode.OK, time); } The first one accepts a string and if called with a JSON string from the client like this:var client = new HttpClient(); var result = client.PostAsJsonAsync<string>(http://rasxps/AspNetWebApi/albums/rpc/ReturnString, "Hello World").Result; which results in a trace like this: POST http://rasxps/AspNetWebApi/albums/rpc/ReturnString HTTP/1.1Content-Type: application/json; charset=utf-8Host: rasxpsContent-Length: 13Expect: 100-continueConnection: Keep-Alive "Hello World" produces… wait for it: null. Sending a date in the same fashion:var client = new HttpClient(); var result = client.PostAsJsonAsync<DateTime>(http://rasxps/AspNetWebApi/albums/rpc/ReturnDateTime, new DateTime(2012, 1, 1)).Result; results in this trace: POST http://rasxps/AspNetWebApi/albums/rpc/ReturnDateTime HTTP/1.1Content-Type: application/json; charset=utf-8Host: rasxpsContent-Length: 30Expect: 100-continueConnection: Keep-Alive "\/Date(1325412000000-1000)\/" (yes still the ugly MS AJAX date, yuk! This will supposedly change by RTM with Json.net used for client serialization) produces an error response: The parameters dictionary contains a null entry for parameter 'time' of non-nullable type 'System.DateTime' for method 'System.Net.Http.HttpResponseMessage ReturnDateTime(System.DateTime)' in 'AspNetWebApi.Controllers.AlbumApiController'. An optional parameter must be a reference type, a nullable type, or be declared as an optional parameter. Basically any simple parameters are not parsed properly resulting in null being sent to the method. For the string the call doesn't fail, but for the non-nullable date it produces an error because the method can't handle a null value. This behavior is a bit unexpected to say the least, but there's a simple solution to make this work using an explicit [FromBody] attribute:public string ReturnString([FromBody] string message) andpublic HttpResponseMessage ReturnDateTime([FromBody] DateTime time) which explicitly instructs Web API to read the value from the body. UrlEncoded Form Variable Parsing Another similar issue I ran into is with POST Form Variable binding. Web API can retrieve parameters from the QueryString and Route Values but it doesn't explicitly map parameters from POST values either. Taking our same ReturnString function from earlier and posting a message POST variable like this:var formVars = new Dictionary<string,string>(); formVars.Add("message", "Some Value"); var content = new FormUrlEncodedContent(formVars); var client = new HttpClient(); var result = client.PostAsync(http://rasxps/AspNetWebApi/albums/rpc/ReturnString, content).Result; which produces this trace: POST http://rasxps/AspNetWebApi/albums/rpc/ReturnString HTTP/1.1Content-Type: application/x-www-form-urlencodedHost: rasxpsContent-Length: 18Expect: 100-continue message=Some+Value When calling ReturnString:public string ReturnString(string message) { return message; } unfortunately it does not map the message value to the message parameter. This sort of mapping unfortunately is not available in Web API. Web API does support binding to form variables but only as part of model binding, which binds object properties to the POST variables. Sending the same message as in the previous example you can use the following code to pick up POST variable data:public string ReturnMessageModel(MessageModel model) { return model.Message; } public class MessageModel { public string Message { get; set; }} Note that the model is bound and the message form variable is mapped to the Message property as would other variables to properties if there were more. This works but it's not very dynamic. There's no real easy way to retrieve form variables (or query string values for that matter) in Web API's Request object as far as I can discern. Well only if you consider this easy:public string ReturnString() { var formData = Request.Content.ReadAsAsync<FormDataCollection>().Result; return formData.Get("message"); } Oddly FormDataCollection does not allow for indexers to work so you have to use the .Get() method which is rather odd. If you're running under IIS/Cassini you can always resort to the old and trusty HttpContext access for request data:public string ReturnString() { return HttpContext.Current.Request.Form["message"]; } which works fine and is easier. It's kind of a bummer that HttpRequestMessage doesn't expose some sort of raw Request object that has access to dynamic data - given that it's meant to serve as a generic REST/HTTP API that seems like a crucial missing piece. I don't see any way to read query string values either. To me personally HttpContext works, since I don't see myself using self-hosted code much.© Rick Strahl, West Wind Technologies, 2005-2012Posted in Web Api   Tweet !function(d,s,id){var js,fjs=d.getElementsByTagName(s)[0];if(!d.getElementById(id)){js=d.createElement(s);js.id=id;js.src="//platform.twitter.com/widgets.js";fjs.parentNode.insertBefore(js,fjs);}}(document,"script","twitter-wjs"); (function() { var po = document.createElement('script'); po.type = 'text/javascript'; po.async = true; po.src = 'https://apis.google.com/js/plusone.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(po, s); })();

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  • wcf web service in post method, object properties are null, although the object is not null

    - by Abdalhadi Kolayb
    i have this problem in post method when i send object parameter to the method, then the object is not null, but all its properties have the default values. here is data module: [DataContract] public class Products { [DataMember(Order = 1)] public int ProdID { get; set; } [DataMember(Order = 2)] public string ProdName { get; set; } [DataMember(Order = 3)] public float PrpdPrice { get; set; } } and here is the interface: [OperationContract] [WebInvoke( Method = "POST", UriTemplate = "AddProduct", ResponseFormat = WebMessageFormat.Json, BodyStyle = WebMessageBodyStyle.WrappedRequest, RequestFormat = WebMessageFormat.Json)] string AddProduct([MessageParameter(Name = "prod")]Products prod); public string AddProduct(Products prod) { ProductsList.Add(prod); return "return string"; } here is the json request: Content-type:application/json {"prod":[{"ProdID": 111,"ProdName": "P111","PrpdPrice": 111}]} but in the server the object received: {"prod":[{"ProdID": 0,"ProdName": NULL,"PrpdPrice": 0}]}

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  • International Radio Operators Alphabet in F# &amp; Silverlight &ndash; Part 2

    - by MarkPearl
    So the brunt of my my very complex F# code has been done. Now it’s just putting the Silverlight stuff in. The first thing I did was add a new project to my solution. I gave it a name and VS2010 did the rest of the magic in creating the .Web project etc. In this instance because I want to take the MVVM approach and make use of commanding I have decided to make the frontend a Silverlight4 project. I now need move my F# code into a proper Silverlight Library. Warning – when you create the Silverlight Library VS2010 will ask you whether you want it to be based on Silverlight3 or Silverlight4. I originally went for Silverlight4 only to discover when I tried to compile my solution that I was given an error… Error 12 F# runtime for Silverlight version v4.0 is not installed. Please go to http://go.microsoft.com/fwlink/?LinkId=177463 to download and install matching.. After asking around I discovered that the Silverlight4 F# runtime is not available yet. No problem, the suggestion was to change the F# Silverlight Library to a Silverlight3 project however when going to the properties of the project file – even though I changed it to Silverlight3, VS2010 did not like it and kept reverting it to a Silverlight4 project. After a few minutes of scratching my head I simply deleted Silverlight4 F# Library project and created a new F# Silverlight Library project in Silverlight3 and VS2010 was happy. Now that the project structure is set up, rest is fairly simple. You need to add the Silverlight Library as a reference to the C# Silverlight Front End. Then setup your views, since I was following the MVVM pattern I made a Views & ViewModel folder and set up the relevant View and ViewModels. The MainPageViewModel file looks as follows using System; using System.Net; using System.Windows; using System.Windows.Controls; using System.Windows.Documents; using System.Windows.Ink; using System.Windows.Input; using System.Windows.Media; using System.Windows.Media.Animation; using System.Windows.Shapes; using System.Collections.ObjectModel; namespace IROAFrontEnd.ViewModels { public class MainPageViewModel : ViewModelBase { private string _iroaString; private string _inputCharacters; public string InputCharacters { get { return _inputCharacters; } set { if (_inputCharacters != value) { _inputCharacters = value; OnPropertyChanged("InputCharacters"); } } } public string IROAString { get { return _iroaString; } set { if (_iroaString != value) { _iroaString = value; OnPropertyChanged("IROAString"); } } } public ICommand MySpecialCommand { get { return new MyCommand(this); } } public class MyCommand : ICommand { readonly MainPageViewModel _myViewModel; public MyCommand(MainPageViewModel myViewModel) { _myViewModel = myViewModel; } public event EventHandler CanExecuteChanged; public bool CanExecute(object parameter) { return true; } public void Execute(object parameter) { var result = ModuleMain.ConvertCharsToStrings(_myViewModel.InputCharacters); var newString = ""; foreach (var Item in result) { newString += Item + " "; } _myViewModel.IROAString = newString.Trim(); } } } } One of the features I like in Silverlight4 is the new commanding. You will notice in my I have put the code under the command execute to reference to my F# module. At the moment this could be cleaned up even more, but will suffice for now.. public void Execute(object parameter) { var result = ModuleMain.ConvertCharsToStrings(_myViewModel.InputCharacters); var newString = ""; foreach (var Item in result) { newString += Item + " "; } _myViewModel.IROAString = newString.Trim(); } I then needed to set the view up. If we have a look at the MainPageView.xaml the xaml code will look like the following…. Nothing to fancy, but battleship grey for now… take careful note of the binding of the command in the button to MySpecialCommand which was created in the ViewModel. <UserControl x:Class="IROAFrontEnd.Views.MainPageView" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:d="http://schemas.microsoft.com/expression/blend/2008" xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" mc:Ignorable="d" d:DesignHeight="300" d:DesignWidth="400"> <Grid x:Name="LayoutRoot" Background="White"> <Grid.RowDefinitions> <RowDefinition/> <RowDefinition/> <RowDefinition/> </Grid.RowDefinitions> <TextBox Grid.Row="0" Text="{Binding InputCharacters, Mode=TwoWay}"/> <Button Grid.Row="1" Command="{Binding MySpecialCommand}"> <TextBlock Text="Generate"/> </Button> <TextBlock Grid.Row="2" Text="{Binding IROAString}"/> </Grid> </UserControl> Finally in the App.xaml.cs file we need to set the View and link it to the ViewModel. private void Application_Startup(object sender, StartupEventArgs e) { var myView = new MainPageView(); var myViewModel = new MainPageViewModel(); myView.DataContext = myViewModel; this.RootVisual = myView; }   Once this is done – hey presto – it worked. I typed in some “Test Input” and clicked the generate button and the correct Radio Operators Alphabet was generated. And that’s the end of my first very basic F# Silverlight application.

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  • Code refactoring with Visual Studio 2010 Part-1

    - by Jalpesh P. Vadgama
    Visual studio 2010 is a Great IDE(Integrated Development Environment) and we all are using it in day by day for our coding purpose. There are many great features provided by Visual Studio 2010 and Today I am going to show one of great feature called for code refactoring. This feature is one of the most unappreciated features of Visual Studio 2010 as lots of people still not using that and doing stuff manfully. So to explain feature let’s create a simple console application which will print first name and last name like following. And following is code for that. using System; namespace CodeRefractoring { class Program { static void Main(string[] args) { string firstName = "Jalpesh"; string lastName = "Vadgama"; Console.WriteLine(string.Format("FirstName:{0}",firstName)); Console.WriteLine(string.Format("LastName:{0}", lastName)); Console.ReadLine(); } } } So as you can see this is a very basic console application and let’s run it to see output. So now lets explore our first feature called extract method in visual studio you can also do that via refractor menu like following. Just select the code for which you want to extract method and then click refractor menu and then click extract method. Now I am selecting three lines of code and clicking on refactor –> Extract Method just like following. Once you click menu a dialog box will appear like following. As you can I have highlighted two thing first is Method Name where I put Print as Method Name and another one Preview method signature where its smart enough to extract parameter also as We have just selected three lines with  console.writeline.  One you click ok it will extract the method and you code will be like this. using System; namespace CodeRefractoring { class Program { static void Main(string[] args) { string firstName = "Jalpesh"; string lastName = "Vadgama"; Print(firstName, lastName); } private static void Print(string firstName, string lastName) { Console.WriteLine(string.Format("FirstName:{0}", firstName)); Console.WriteLine(string.Format("LastName:{0}", lastName)); Console.ReadLine(); } } } So as you can see in above code its has created a static method called Print and also passed parameter for as firstname and lastname. Isn’t that great!!!. It has also created static print method as I am calling it from static void main.  Hope you liked it.. Stay tuned for more..Till that Happy programming.

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  • Salt and hash a password in .NET

    - by Jon Canning
    I endeavoured to follow the CrackStation rules: Salted Password Hashing - Doing it Right    public class SaltedHash     {         public string Hash { get; private set; }         public string Salt { get; private set; }         public SaltedHash(string password)         {             var saltBytes = new byte[32];             new RNGCryptoServiceProvider().GetNonZeroBytes(saltBytes);             Salt = ConvertToBase64String(saltBytes);             var passwordAndSaltBytes = Concat(password, saltBytes);             Hash = ComputeHash(passwordAndSaltBytes);         }         static string ConvertToBase64String(byte[] bytes)         {             return Convert.ToBase64String(bytes);         }         static string ComputeHash(byte[] bytes)         {             return ConvertToBase64String(SHA256.Create().ComputeHash(bytes));         }         static byte[] Concat(string password, byte[] saltBytes)         {             var passwordBytes = Encoding.UTF8.GetBytes(password);             return passwordBytes.Concat(saltBytes).ToArray();         }         public static bool Verify(string salt, string hash, string password)         {             var saltBytes = Convert.FromBase64String(salt);             var passwordAndSaltBytes = Concat(password, saltBytes);             var hashAttempt = ComputeHash(passwordAndSaltBytes);             return hash == hashAttempt;         }     }

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  • How to Share Files Between User Accounts on Windows, Linux, or OS X

    - by Chris Hoffman
    Your operating system provides each user account with its own folders when you set up several different user accounts on the same computer. Shared folders allow you to share files between user accounts. This process works similarly on Windows, Linux, and Mac OS X. These are all powerful multi-user operating systems with similar folder and file permission systems. Windows On Windows, the “Public” user’s folders are accessible to all users. You’ll find this folder under C:\Users\Public by default. Files you place in any of these folders will be accessible to other users, so it’s a good way to share music, videos, and other types of files between users on the same computer. Windows even adds these folders to each user’s libraries by default. For example, a user’s Music library contains the user’s music folder under C:\Users\NAME\as well as the public music folder under C:\Users\Public\. This makes it easy for each user to find the shared, public files. It also makes it easy to make a file public — just drag and drop a file from the user-specific folder to the public folder in the library. Libraries are hidden by default on Windows 8.1, so you’ll have to unhide them to do this. These Public folders can also be used to share folders publically on the local network. You’ll find the Public folder sharing option under Advanced sharing settings in the Network and Sharing Control Panel. You could also choose to make any folder shared between users, but this will require messing with folder permissions in Windows. To do this, right-click a folder anywhere in the file system and select Properties. Use the options on the Security tab to change the folder’s permissions and make it accessible to different user accounts. You’ll need administrator access to do this. Linux This is a bit more complicated on Linux, as typical Linux distributions don’t come with a special user folder all users have read-write access to. The Public folder on Ubuntu is for sharing files between computers on a network. You can use Linux’s permissions system to give other user accounts read or read-write access to specific folders. The process below is for Ubuntu 14.04, but it should be identical on any other Linux distribution using GNOME with the Nautilus file manager. It should be similar for other desktop environments, too. Locate the folder you want to make accessible to other users, right-click it, and select Properties. On the Permissions tab, give “Others” the “Create and delete files” permission. Click the Change Permissions for Enclosed Files button and give “Others” the “Read and write” and “Create and Delete Files” permissions. Other users on the same computer will then have read and write access to your folder. They’ll find it under /home/YOURNAME/folder under Computer. To speed things up, they can create a link or bookmark to the folder so they always have easy access to it. Mac OS X Mac OS X creates a special Shared folder that all user accounts have access to. This folder is intended for sharing files between different user accounts. It’s located at /Users/Shared. To access it, open the Finder and click Go > Computer. Navigate to Macintosh HD > Users > Shared. Files you place in this folder can be accessed by any user account on your Mac. These tricks are useful if you’re sharing a computer with other people and you all have your own user accounts — maybe your kids have their own limited accounts. You can share a music library, downloads folder, picture archive, videos, documents, or anything else you like without keeping duplicate copies.

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  • Using TPL and PLINQ to raise performance of feed aggregator

    - by DigiMortal
    In this posting I will show you how to use Task Parallel Library (TPL) and PLINQ features to boost performance of simple RSS-feed aggregator. I will use here only very basic .NET classes that almost every developer starts from when learning parallel programming. Of course, we will also measure how every optimization affects performance of feed aggregator. Feed aggregator Our feed aggregator works as follows: Load list of blogs Download RSS-feed Parse feed XML Add new posts to database Our feed aggregator is run by task scheduler after every 15 minutes by example. We will start our journey with serial implementation of feed aggregator. Second step is to use task parallelism and parallelize feeds downloading and parsing. And our last step is to use data parallelism to parallelize database operations. We will use Stopwatch class to measure how much time it takes for aggregator to download and insert all posts from all registered blogs. After every run we empty posts table in database. Serial aggregation Before doing parallel stuff let’s take a look at serial implementation of feed aggregator. All tasks happen one after other. internal class FeedClient {     private readonly INewsService _newsService;     private const int FeedItemContentMaxLength = 255;       public FeedClient()     {          ObjectFactory.Initialize(container =>          {              container.PullConfigurationFromAppConfig = true;          });           _newsService = ObjectFactory.GetInstance<INewsService>();     }       public void Execute()     {         var blogs = _newsService.ListPublishedBlogs();           for (var index = 0; index <blogs.Count; index++)         {              ImportFeed(blogs[index]);         }     }       private void ImportFeed(BlogDto blog)     {         if(blog == null)             return;         if (string.IsNullOrEmpty(blog.RssUrl))             return;           var uri = new Uri(blog.RssUrl);         SyndicationContentFormat feedFormat;           feedFormat = SyndicationDiscoveryUtility.SyndicationContentFormatGet(uri);           if (feedFormat == SyndicationContentFormat.Rss)             ImportRssFeed(blog);         if (feedFormat == SyndicationContentFormat.Atom)             ImportAtomFeed(blog);                 }       private void ImportRssFeed(BlogDto blog)     {         var uri = new Uri(blog.RssUrl);         var feed = RssFeed.Create(uri);           foreach (var item in feed.Channel.Items)         {             SaveRssFeedItem(item, blog.Id, blog.CreatedById);         }     }       private void ImportAtomFeed(BlogDto blog)     {         var uri = new Uri(blog.RssUrl);         var feed = AtomFeed.Create(uri);           foreach (var item in feed.Entries)         {             SaveAtomFeedEntry(item, blog.Id, blog.CreatedById);         }     } } Serial implementation of feed aggregator downloads and inserts all posts with 25.46 seconds. Task parallelism Task parallelism means that separate tasks are run in parallel. You can find out more about task parallelism from MSDN page Task Parallelism (Task Parallel Library) and Wikipedia page Task parallelism. Although finding parts of code that can run safely in parallel without synchronization issues is not easy task we are lucky this time. Feeds import and parsing is perfect candidate for parallel tasks. We can safely parallelize feeds import because importing tasks doesn’t share any resources and therefore they don’t also need any synchronization. After getting the list of blogs we iterate through the collection and start new TPL task for each blog feed aggregation. internal class FeedClient {     private readonly INewsService _newsService;     private const int FeedItemContentMaxLength = 255;       public FeedClient()     {          ObjectFactory.Initialize(container =>          {              container.PullConfigurationFromAppConfig = true;          });           _newsService = ObjectFactory.GetInstance<INewsService>();     }       public void Execute()     {         var blogs = _newsService.ListPublishedBlogs();                var tasks = new Task[blogs.Count];           for (var index = 0; index <blogs.Count; index++)         {             tasks[index] = new Task(ImportFeed, blogs[index]);             tasks[index].Start();         }           Task.WaitAll(tasks);     }       private void ImportFeed(object blogObject)     {         if(blogObject == null)             return;         var blog = (BlogDto)blogObject;         if (string.IsNullOrEmpty(blog.RssUrl))             return;           var uri = new Uri(blog.RssUrl);         SyndicationContentFormat feedFormat;           feedFormat = SyndicationDiscoveryUtility.SyndicationContentFormatGet(uri);           if (feedFormat == SyndicationContentFormat.Rss)             ImportRssFeed(blog);         if (feedFormat == SyndicationContentFormat.Atom)             ImportAtomFeed(blog);                }       private void ImportRssFeed(BlogDto blog)     {          var uri = new Uri(blog.RssUrl);          var feed = RssFeed.Create(uri);           foreach (var item in feed.Channel.Items)          {              SaveRssFeedItem(item, blog.Id, blog.CreatedById);          }     }     private void ImportAtomFeed(BlogDto blog)     {         var uri = new Uri(blog.RssUrl);         var feed = AtomFeed.Create(uri);           foreach (var item in feed.Entries)         {             SaveAtomFeedEntry(item, blog.Id, blog.CreatedById);         }     } } You should notice first signs of the power of TPL. We made only minor changes to our code to parallelize blog feeds aggregating. On my machine this modification gives some performance boost – time is now 17.57 seconds. Data parallelism There is one more way how to parallelize activities. Previous section introduced task or operation based parallelism, this section introduces data based parallelism. By MSDN page Data Parallelism (Task Parallel Library) data parallelism refers to scenario in which the same operation is performed concurrently on elements in a source collection or array. In our code we have independent collections we can process in parallel – imported feed entries. As checking for feed entry existence and inserting it if it is missing from database doesn’t affect other entries the imported feed entries collection is ideal candidate for parallelization. internal class FeedClient {     private readonly INewsService _newsService;     private const int FeedItemContentMaxLength = 255;       public FeedClient()     {          ObjectFactory.Initialize(container =>          {              container.PullConfigurationFromAppConfig = true;          });           _newsService = ObjectFactory.GetInstance<INewsService>();     }       public void Execute()     {         var blogs = _newsService.ListPublishedBlogs();                var tasks = new Task[blogs.Count];           for (var index = 0; index <blogs.Count; index++)         {             tasks[index] = new Task(ImportFeed, blogs[index]);             tasks[index].Start();         }           Task.WaitAll(tasks);     }       private void ImportFeed(object blogObject)     {         if(blogObject == null)             return;         var blog = (BlogDto)blogObject;         if (string.IsNullOrEmpty(blog.RssUrl))             return;           var uri = new Uri(blog.RssUrl);         SyndicationContentFormat feedFormat;           feedFormat = SyndicationDiscoveryUtility.SyndicationContentFormatGet(uri);           if (feedFormat == SyndicationContentFormat.Rss)             ImportRssFeed(blog);         if (feedFormat == SyndicationContentFormat.Atom)             ImportAtomFeed(blog);                }       private void ImportRssFeed(BlogDto blog)     {         var uri = new Uri(blog.RssUrl);         var feed = RssFeed.Create(uri);           feed.Channel.Items.AsParallel().ForAll(a =>         {             SaveRssFeedItem(a, blog.Id, blog.CreatedById);         });      }        private void ImportAtomFeed(BlogDto blog)      {         var uri = new Uri(blog.RssUrl);         var feed = AtomFeed.Create(uri);           feed.Entries.AsParallel().ForAll(a =>         {              SaveAtomFeedEntry(a, blog.Id, blog.CreatedById);         });      } } We did small change again and as the result we parallelized checking and saving of feed items. This change was data centric as we applied same operation to all elements in collection. On my machine I got better performance again. Time is now 11.22 seconds. Results Let’s visualize our measurement results (numbers are given in seconds). As we can see then with task parallelism feed aggregation takes about 25% less time than in original case. When adding data parallelism to task parallelism our aggregation takes about 2.3 times less time than in original case. More about TPL and PLINQ Adding parallelism to your application can be very challenging task. You have to carefully find out parts of your code where you can safely go to parallel processing and even then you have to measure the effects of parallel processing to find out if parallel code performs better. If you are not careful then troubles you will face later are worse than ones you have seen before (imagine error that occurs by average only once per 10000 code runs). Parallel programming is something that is hard to ignore. Effective programs are able to use multiple cores of processors. Using TPL you can also set degree of parallelism so your application doesn’t use all computing cores and leaves one or more of them free for host system and other processes. And there are many more things in TPL that make it easier for you to start and go on with parallel programming. In next major version all .NET languages will have built-in support for parallel programming. There will be also new language constructs that support parallel programming. Currently you can download Visual Studio Async to get some idea about what is coming. Conclusion Parallel programming is very challenging but good tools offered by Visual Studio and .NET Framework make it way easier for us. In this posting we started with feed aggregator that imports feed items on serial mode. With two steps we parallelized feed importing and entries inserting gaining 2.3 times raise in performance. Although this number is specific to my test environment it shows clearly that parallel programming may raise the performance of your application significantly.

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  • Parent Objects

    - by Ali Bahrami
    Support for Parent Objects was added in Solaris 11 Update 1. The following material is adapted from the PSARC arc case, and the Solaris Linker and Libraries Manual. A "plugin" is a shared object, usually loaded via dlopen(), that is used by a program in order to allow the end user to add functionality to the program. Examples of plugins include those used by web browsers (flash, acrobat, etc), as well as mdb and elfedit modules. The object that loads the plugin at runtime is called the "parent object". Unlike most object dependencies, the parent is not identified by name, but by its status as the object doing the load. Historically, building a good plugin is has been more complicated than it should be: A parent and its plugin usually share a 2-way dependency: The plugin provides one or more routines for the parent to call, and the parent supplies support routines for use by the plugin for things like memory allocation and error reporting. It is a best practice to build all objects, including plugins, with the -z defs option, in order to ensure that the object specifies all of its dependencies, and is self contained. However: The parent is usually an executable, which cannot be linked to via the usual library mechanisms provided by the link editor. Even if the parent is a shared object, which could be a normal library dependency to the plugin, it may be desirable to build plugins that can be used by more than one parent, in which case embedding a dependency NEEDED entry for one of the parents is undesirable. The usual way to build a high quality plugin with -z defs uses a special mapfile provided by the parent. This mapfile defines the parent routines, specifying the PARENT attribute (see example below). This works, but is inconvenient, and error prone. The symbol table in the parent already describes what it makes available to plugins — ideally the plugin would obtain that information directly rather than from a separate mapfile. The new -z parent option to ld allows a plugin to link to the parent and access the parent symbol table. This differs from a typical dependency: No NEEDED record is created. The relationship is recorded as a logical connection to the parent, rather than as an explicit object name However, it operates in the same manner as any other dependency in terms of making symbols available to the plugin. When the -z parent option is used, the link-editor records the basename of the parent object in the dynamic section, using the new tag DT_SUNW_PARENT. This is an informational tag, which is not used by the runtime linker to locate the parent, but which is available for diagnostic purposes. The ld(1) manpage documentation for the -z parent option is: -z parent=object Specifies a "parent object", which can be an executable or shared object, against which to link the output object. This option is typically used when creating "plugin" shared objects intended to be loaded by an executable at runtime via the dlopen() function. The symbol table from the parent object is used to satisfy references from the plugin object. The use of the -z parent option makes symbols from the object calling dlopen() available to the plugin. Example For this example, we use a main program, and a plugin. The parent provides a function named parent_callback() for the plugin to call. The plugin provides a function named plugin_func() to the parent: % cat main.c #include <stdio.h> #include <dlfcn.h> #include <link.h> void parent_callback(void) { printf("plugin_func() has called parent_callback()\n"); } int main(int argc, char **argv) { typedef void plugin_func_t(void); void *hdl; plugin_func_t *plugin_func; if (argc != 2) { fprintf(stderr, "usage: main plugin\n"); return (1); } if ((hdl = dlopen(argv[1], RTLD_LAZY)) == NULL) { fprintf(stderr, "unable to load plugin: %s\n", dlerror()); return (1); } plugin_func = (plugin_func_t *) dlsym(hdl, "plugin_func"); if (plugin_func == NULL) { fprintf(stderr, "unable to find plugin_func: %s\n", dlerror()); return (1); } (*plugin_func)(); return (0); } % cat plugin.c #include <stdio.h> extern void parent_callback(void); void plugin_func(void) { printf("parent has called plugin_func() from plugin.so\n"); parent_callback(); } Building this in the traditional manner, without -zdefs: % cc -o main main.c % cc -G -o plugin.so plugin.c % ./main ./plugin.so parent has called plugin_func() from plugin.so plugin_func() has called parent_callback() As noted above, when building any shared object, the -z defs option is recommended, in order to ensure that the object is self contained and specifies all of its dependencies. However, the use of -z defs prevents the plugin object from linking due to the unsatisfied symbol from the parent object: % cc -zdefs -G -o plugin.so plugin.c Undefined first referenced symbol in file parent_callback plugin.o ld: fatal: symbol referencing errors. No output written to plugin.so A mapfile can be used to specify to ld that the parent_callback symbol is supplied by the parent object. % cat plugin.mapfile $mapfile_version 2 SYMBOL_SCOPE { global: parent_callback { FLAGS = PARENT }; }; % cc -zdefs -Mplugin.mapfile -G -o plugin.so plugin.c However, the -z parent option to ld is the most direct solution to this problem, allowing the plugin to actually link against the parent object, and obtain the available symbols from it. An added benefit of using -z parent instead of a mapfile, is that the name of the parent object is recorded in the dynamic section of the plugin, and can be displayed by the file utility: % cc -zdefs -zparent=main -G -o plugin.so plugin.c % elfdump -d plugin.so | grep PARENT [0] SUNW_PARENT 0xcc main % file plugin.so plugin.so: ELF 32-bit LSB dynamic lib 80386 Version 1, parent main, dynamically linked, not stripped % ./main ./plugin.so parent has called plugin_func() from plugin.so plugin_func() has called parent_callback() We can also observe this in elfedit plugins on Solaris systems running Solaris 11 Update 1 or newer: % file /usr/lib/elfedit/dyn.so /usr/lib/elfedit/dyn.so: ELF 32-bit LSB dynamic lib 80386 Version 1, parent elfedit, dynamically linked, not stripped, no debugging information available Related Other Work The GNU ld has an option named --just-symbols that can be used in a similar manner: --just-symbols=filename Read symbol names and their addresses from filename, but do not relocate it or include it in the output. This allows your output file to refer symbolically to absolute locations of memory defined in other programs. You may use this option more than once. -z parent is a higher level operation aimed specifically at simplifying the construction of high quality plugins. Although it employs the same operation, it differs from --just symbols in 2 significant ways: There can only be one parent. The parent is recorded in the created object, and can be displayed by 'file', or other similar tools.

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  • Write your Tests in RSpec with IronRuby

    - by kazimanzurrashid
    [Note: This is not a continuation of my previous post, treat it as an experiment out in the wild. ] Lets consider the following class, a fictitious Fund Transfer Service: public class FundTransferService : IFundTransferService { private readonly ICurrencyConvertionService currencyConvertionService; public FundTransferService(ICurrencyConvertionService currencyConvertionService) { this.currencyConvertionService = currencyConvertionService; } public void Transfer(Account fromAccount, Account toAccount, decimal amount) { decimal convertionRate = currencyConvertionService.GetConvertionRate(fromAccount.Currency, toAccount.Currency); decimal convertedAmount = convertionRate * amount; fromAccount.Withdraw(amount); toAccount.Deposit(convertedAmount); } } public class Account { public Account(string currency, decimal balance) { Currency = currency; Balance = balance; } public string Currency { get; private set; } public decimal Balance { get; private set; } public void Deposit(decimal amount) { Balance += amount; } public void Withdraw(decimal amount) { Balance -= amount; } } We can write the spec with MSpec + Moq like the following: public class When_fund_is_transferred { const decimal ConvertionRate = 1.029m; const decimal TransferAmount = 10.0m; const decimal InitialBalance = 100.0m; static Account fromAccount; static Account toAccount; static FundTransferService fundTransferService; Establish context = () => { fromAccount = new Account("USD", InitialBalance); toAccount = new Account("CAD", InitialBalance); var currencyConvertionService = new Moq.Mock<ICurrencyConvertionService>(); currencyConvertionService.Setup(ccv => ccv.GetConvertionRate(Moq.It.IsAny<string>(), Moq.It.IsAny<string>())).Returns(ConvertionRate); fundTransferService = new FundTransferService(currencyConvertionService.Object); }; Because of = () => { fundTransferService.Transfer(fromAccount, toAccount, TransferAmount); }; It should_decrease_from_account_balance = () => { fromAccount.Balance.ShouldBeLessThan(InitialBalance); }; It should_increase_to_account_balance = () => { toAccount.Balance.ShouldBeGreaterThan(InitialBalance); }; } and if you run the spec it will give you a nice little output like the following: When fund is transferred » should decrease from account balance » should increase to account balance 2 passed, 0 failed, 0 skipped, took 1.14 seconds (MSpec). Now, lets see how we can write exact spec in RSpec. require File.dirname(__FILE__) + "/../FundTransfer/bin/Debug/FundTransfer" require "spec" require "caricature" describe "When fund is transferred" do Convertion_Rate = 1.029 Transfer_Amount = 10.0 Initial_Balance = 100.0 before(:all) do @from_account = FundTransfer::Account.new("USD", Initial_Balance) @to_account = FundTransfer::Account.new("CAD", Initial_Balance) currency_convertion_service = Caricature::Isolation.for(FundTransfer::ICurrencyConvertionService) currency_convertion_service.when_receiving(:get_convertion_rate).with(:any, :any).return(Convertion_Rate) fund_transfer_service = FundTransfer::FundTransferService.new(currency_convertion_service) fund_transfer_service.transfer(@from_account, @to_account, Transfer_Amount) end it "should decrease from account balance" do @from_account.balance.should be < Initial_Balance end it "should increase to account balance" do @to_account.balance.should be > Initial_Balance end end I think the above code is self explanatory, treat the require(line 1- 4) statements as the add reference of our visual studio projects, we are adding all the required libraries with this statement. Next, the describe which is a RSpec keyword. The before does exactly the same as NUnit's Setup or MsTest’s TestInitialize attribute, but in the above we are using before(:all) which acts as ClassInitialize of MsTest, that means it will be executed only once before all the test methods. In the before(:all) we are first instantiating the from and to accounts, it is same as creating with the full name (including namespace)  like fromAccount = new FundTransfer.Account(.., ..), next, we are creating a mock object of ICurrencyConvertionService, check that for creating the mock we are not using the Moq like the MSpec version. This is somewhat an interesting issue of IronRuby or maybe the DLR, it seems that it is not possible to use the lambda expression that most of the mocking tools uses in arrange phase in Iron Ruby, like: currencyConvertionService.Setup(ccv => ccv.GetConvertionRate(Moq.It.IsAny<string>(), Moq.It.IsAny<string>())).Returns(ConvertionRate); But the good news is, there is already an excellent mocking tool called Caricature written completely in IronRuby which we can use to mock the .NET classes. May be all the mocking tool providers should give some thought to add the support for the DLR, so that we can use the tool that we are already familiar with. I think the rest of the code is too simple, so I am skipping the explanation. Now, the last thing, how we are going to run it with RSpec, lets first install the required gems. Open you command prompt and type the following: igem sources -a http://gems.github.com This will add the GitHub as gem source. Next type: igem install uuidtools caricature rspec and at last we have to create a batch file so that we can execute it in the Notepad++, create a batch like in the IronRuby bin directory like my previous post and put the following in that batch file: @echo off cls call spec %1 --format specdoc pause Next, add a run menu and shortcut in the Notepad++ like my previous post. Now when we run it it will show the following output: When fund is transferred - should decrease from account balance - should increase to account balance Finished in 0.332042 seconds 2 examples, 0 failures Press any key to continue . . . You will complete code of this post in the bottom. That's it for today. Download: RSpecIntegration.zip

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  • Making your WCF Web Apis to speak in multiple languages

    - by cibrax
    One of the key aspects of how the web works today is content negotiation. The idea of content negotiation is based on the fact that a single resource can have multiple representations, so user agents (or clients) and servers can work together to chose one of them. The http specification defines several “Accept” headers that a client can use to negotiate content with a server, and among all those, there is one for restricting the set of natural languages that are preferred as a response to a request, “Accept-Language”. For example, a client can specify “es” in this header for specifying that he prefers to receive the content in spanish or “en” in english. However, there are certain scenarios where the “Accept-Language” header is just not enough, and you might want to have a way to pass the “accepted” language as part of the resource url as an extension. For example, http://localhost/ProductCatalog/Products/1.es” returns all the descriptions for the product with id “1” in spanish. This is useful for scenarios in which you want to embed the link somewhere, such a document, an email or a page.  Supporting both scenarios, the header and the url extension, is really simple in the new WCF programming model. You only need to provide a processor implementation for any of them. Let’s say I have a resource implementation as part of a product catalog I want to expose with the WCF web apis. [ServiceContract][Export]public class ProductResource{ IProductRepository repository;  [ImportingConstructor] public ProductResource(IProductRepository repository) { this.repository = repository; }  [WebGet(UriTemplate = "{id}")] public Product Get(string id, HttpResponseMessage response) { var product = repository.GetById(int.Parse(id)); if (product == null) { response.StatusCode = HttpStatusCode.NotFound; response.Content = new StringContent(Messages.OrderNotFound); }  return product; }} The Get method implementation in this resource assumes the desired culture will be attached to the current thread (Thread.CurrentThread.Culture). Another option is to pass the desired culture as an additional argument in the method, so my processor implementation will handle both options. This method is also using an auto-generated class for handling string resources, Messages, which is available in the different cultures that the service implementation supports. For example, Messages.resx contains “OrderNotFound”: “Order Not Found” Messages.es.resx contains “OrderNotFound”: “No se encontro orden” The processor implementation bellow tackles the first scenario, in which the desired language is passed as part of the “Accept-Language” header. public class CultureProcessor : Processor<HttpRequestMessage, CultureInfo>{ string defaultLanguage = null;  public CultureProcessor(string defaultLanguage = "en") { this.defaultLanguage = defaultLanguage; this.InArguments[0].Name = HttpPipelineFormatter.ArgumentHttpRequestMessage; this.OutArguments[0].Name = "culture"; }  public override ProcessorResult<CultureInfo> OnExecute(HttpRequestMessage request) { CultureInfo culture = null; if (request.Headers.AcceptLanguage.Count > 0) { var language = request.Headers.AcceptLanguage.First().Value; culture = new CultureInfo(language); } else { culture = new CultureInfo(defaultLanguage); }  Thread.CurrentThread.CurrentCulture = culture; Messages.Culture = culture;  return new ProcessorResult<CultureInfo> { Output = culture }; }}   As you can see, the processor initializes a new CultureInfo instance with the value provided in the “Accept-Language” header, and set that instance to the current thread and the auto-generated resource class with all the messages. In addition, the CultureInfo instance is returned as an output argument called “culture”, making possible to receive that argument in any method implementation   The following code shows the implementation of the processor for handling languages as url extensions.   public class CultureExtensionProcessor : Processor<HttpRequestMessage, Uri>{ public CultureExtensionProcessor() { this.OutArguments[0].Name = HttpPipelineFormatter.ArgumentUri; }  public override ProcessorResult<Uri> OnExecute(HttpRequestMessage httpRequestMessage) { var requestUri = httpRequestMessage.RequestUri.OriginalString;  var extensionPosition = requestUri.LastIndexOf(".");  if (extensionPosition > -1) { var extension = requestUri.Substring(extensionPosition + 1);  var query = httpRequestMessage.RequestUri.Query;  requestUri = string.Format("{0}?{1}", requestUri.Substring(0, extensionPosition), query); ;  var uri = new Uri(requestUri);  httpRequestMessage.Headers.AcceptLanguage.Clear();  httpRequestMessage.Headers.AcceptLanguage.Add(new StringWithQualityHeaderValue(extension));  var result = new ProcessorResult<Uri>();  result.Output = uri;  return result; }  return new ProcessorResult<Uri>(); }} The last step is to inject both processors as part of the service configuration as it is shown bellow, public void RegisterRequestProcessorsForOperation(HttpOperationDescription operation, IList<Processor> processors, MediaTypeProcessorMode mode){ processors.Insert(0, new CultureExtensionProcessor()); processors.Add(new CultureProcessor());} Once you configured the two processors in the pipeline, your service will start speaking different languages :). Note: Url extensions don’t seem to be working in the current bits when you are using Url extensions in a base address. As far as I could see, ASP.NET intercepts the request first and tries to route the request to a registered ASP.NET Http Handler with that extension. For example, “http://localhost/ProductCatalog/products.es” does not work, but “http://localhost/ProductCatalog/products/1.es” does.

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  • TFS 2010 SDK: Integrating Twitter with TFS Programmatically

    - by Tarun Arora
    Technorati Tags: Team Foundation Server 2010,TFS API,Integrate Twitter TFS,TFS Programming,ALM,TwitterSharp   Friends at ‘Twitter Sharp’ have created a wonderful .net API for twitter. With this blog post i will try to show you a basic TFS – Twitter integration scenario where i will retrieve the Team Project details programmatically and then publish these details on my twitter page. In future blogs i will be demonstrating how to create a windows service to capture the events raised by TFS and then publishing them in your social eco-system. Download Working Demo: Integrate Twitter - Tfs Programmatically   1. Setting up Twitter API Download Tweet Sharp from => https://github.com/danielcrenna/tweetsharp  Before you can start playing around with this, you will need to register an application on twitter. This is because Twitter uses the OAuth authentication protocol and will not issue an Access token unless your application is registered with them. Go to https://dev.twitter.com/ and register your application   Once you have registered your application, you will need ‘Customer Key’, ‘Customer Secret’, ‘Access Token’, ‘Access Token Secret’ 2. Connecting to Twitter using the Tweet Sharp API Create a new C# windows forms project and add reference to ‘Hammock.ClientProfile’, ‘Newtonsoft.Json’, ‘TweetSharp’ Add the following keys to the App.config (Note – The values for the keys below are in correct and if you try and connect using them then you will get an authorization failure error). Add a new class ‘TwitterProxy’ and use the following code to connect to the TwitterService (Read more about OAuthentication - http://dev.twitter.com/pages/auth) using System;using System.Collections.Generic;using System.Linq;using System.Text;using System.Configuration;using TweetSharp; namespace WindowsFormsApplication2{ public class TwitterProxy { private static string _hero; private static string _consumerKey; private static string _consumerSecret; private static string _accessToken; private static string _accessTokenSecret;  public static TwitterService ConnectToTwitter() { _consumerKey = ConfigurationManager.AppSettings["ConsumerKey"]; _consumerSecret = ConfigurationManager.AppSettings["ConsumerSecret"]; _accessToken = ConfigurationManager.AppSettings["AccessToken"]; _accessTokenSecret = ConfigurationManager.AppSettings["AccessTokenSecret"];  return new TwitterService(_consumerKey, _consumerSecret, _accessToken, _accessTokenSecret); } }} Time to Tweet! _twitterService = Proxy.TwitterProxy.ConnectToTwitter(); _twitterService.SendTweet("Hello World"); SendTweet will return the TweetStatus, If you do not get a 200 OK status that means you have failed authentication, please revisit the Access tokens. --RESPONSE: https://api.twitter.com/1/statuses/update.json HTTP/1.1 200 OK X-Transaction: 1308476106-69292-41752 X-Frame-Options: SAMEORIGIN X-Runtime: 0.03040 X-Transaction-Mask: a6183ffa5f44ef11425211f25 Pragma: no-cache X-Access-Level: read-write X-Revision: DEV X-MID: bd8aa0abeccb6efba38bc0a391a73fab98e983ea Cache-Control: no-cache, no-store, must-revalidate, pre-check=0, post-check=0 Content-Type: application/json; charset=utf-8 Date: Sun, 19 Jun 2011 09:35:06 GMT Expires: Tue, 31 Mar 1981 05:00:00 GMT Last-Modified: Sun, 19 Jun 2011 09:35:06 GMT Server: hi Vary: Accept-Encoding Content-Encoding: Keep-Alive: timeout=15, max=100 Connection: Keep-Alive Transfer-Encoding: chunked   3. Integrate with TFS In my blog post Connect to TFS Programmatically i have in depth demonstrated how to connect to TFS using the TFS API. 1: // Update the AppConfig with the URI of the Team Foundation Server you want to connect to, Make sure you have View Team Project Collection Details permissions on the server 2: private static string _myUri = ConfigurationManager.AppSettings["TfsUri"]; 3: private static TwitterService _twitterService = null; 4:   5: private void button1_Click(object sender, EventArgs e) 6: { 7: lblNotes.Text = string.Empty; 8:   9: try 10: { 11: StringBuilder notes = new StringBuilder(); 12:   13: _twitterService = Proxy.TwitterProxy.ConnectToTwitter(); 14:   15: _twitterService.SendTweet("Hello World"); 16:   17: TfsConfigurationServer configurationServer = 18: TfsConfigurationServerFactory.GetConfigurationServer(new Uri(_myUri)); 19:   20: CatalogNode catalogNode = configurationServer.CatalogNode; 21:   22: ReadOnlyCollection<CatalogNode> tpcNodes = catalogNode.QueryChildren( 23: new Guid[] { CatalogResourceTypes.ProjectCollection }, 24: false, CatalogQueryOptions.None); 25:   26: // tpc = Team Project Collection 27: foreach (CatalogNode tpcNode in tpcNodes) 28: { 29: Guid tpcId = new Guid(tpcNode.Resource.Properties["InstanceId"]); 30: TfsTeamProjectCollection tpc = configurationServer.GetTeamProjectCollection(tpcId); 31:   32: notes.AppendFormat("{0} Team Project Collection : {1}{0}", Environment.NewLine, tpc.Name); 33: _twitterService.SendTweet(String.Format("http://Lunartech.codeplex.com - Connecting to Team Project Collection : {0} ", tpc.Name)); 34:   35: // Get catalog of tp = 'Team Projects' for the tpc = 'Team Project Collection' 36: var tpNodes = tpcNode.QueryChildren( 37: new Guid[] { CatalogResourceTypes.TeamProject }, 38: false, CatalogQueryOptions.None); 39:   40: foreach (var p in tpNodes) 41: { 42: notes.AppendFormat("{0} Team Project : {1} - {2}{0}", Environment.NewLine, p.Resource.DisplayName,  "This is an open source project hosted on codeplex"); 43: _twitterService.SendTweet(String.Format(" Connected to Team Project: '{0}' – '{1}' ", p.Resource.DisplayName, "This is an open source project hosted on codeplex")); 44: } 45: } 46: notes.AppendFormat("{0} Updates posted on Twitter : {1} {0}", Environment.NewLine, @"http://twitter.com/lunartech1"); 47: lblNotes.Text = notes.ToString(); 48: } 49: catch (Exception ex) 50: { 51: lblError.Text = " Message : " + ex.Message + (ex.InnerException != null ? " Inner Exception : " + ex.InnerException : string.Empty); 52: } 53: }   The extensions you can build integrating TFS and Twitter are incredible!   Share this post :

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  • texture mapping with lib3ds and SOIL help

    - by Adam West
    I'm having trouble with my project for loading a texture map onto a model. Any insight into what is going wrong with my code is fantastic. Right now the code only renders a teapot which I have assinged after creating it in 3DS Max. 3dsloader.cpp #include "3dsloader.h" Object::Object(std:: string filename) { m_TotalFaces = 0; m_model = lib3ds_file_load(filename.c_str()); // If loading the model failed, we throw an exception if(!m_model) { throw strcat("Unable to load ", filename.c_str()); } // set properties of texture coordinate generation for both x and y coordinates glTexGeni(GL_S, GL_TEXTURE_GEN_MODE, GL_EYE_LINEAR); glTexGeni(GL_T, GL_TEXTURE_GEN_MODE, GL_EYE_LINEAR); // if not already enabled, enable texture generation if(! glIsEnabled(GL_TEXTURE_GEN_S)) glEnable(GL_TEXTURE_GEN_S); if(! glIsEnabled(GL_TEXTURE_GEN_T)) glEnable(GL_TEXTURE_GEN_T); } Object::~Object() { if(m_model) // if the file isn't freed yet lib3ds_file_free(m_model); //free up memory glDisable(GL_TEXTURE_GEN_S); glDisable(GL_TEXTURE_GEN_T); } void Object::GetFaces() { m_TotalFaces = 0; Lib3dsMesh * mesh; // Loop through every mesh. for(mesh = m_model->meshes;mesh != NULL;mesh = mesh->next) { // Add the number of faces this mesh has to the total number of faces. m_TotalFaces += mesh->faces; } } void Object::CreateVBO() { assert(m_model != NULL); // Calculate the number of faces we have in total GetFaces(); // Allocate memory for our vertices and normals Lib3dsVector * vertices = new Lib3dsVector[m_TotalFaces * 3]; Lib3dsVector * normals = new Lib3dsVector[m_TotalFaces * 3]; Lib3dsTexel* texCoords = new Lib3dsTexel[m_TotalFaces * 3]; Lib3dsMesh * mesh; unsigned int FinishedFaces = 0; // Loop through all the meshes for(mesh = m_model->meshes;mesh != NULL;mesh = mesh->next) { lib3ds_mesh_calculate_normals(mesh, &normals[FinishedFaces*3]); // Loop through every face for(unsigned int cur_face = 0; cur_face < mesh->faces;cur_face++) { Lib3dsFace * face = &mesh->faceL[cur_face]; for(unsigned int i = 0;i < 3;i++) { memcpy(&texCoords[FinishedFaces*3 + i], mesh->texelL[face->points[ i ]], sizeof(Lib3dsTexel)); memcpy(&vertices[FinishedFaces*3 + i], mesh->pointL[face->points[ i ]].pos, sizeof(Lib3dsVector)); } FinishedFaces++; } } // Generate a Vertex Buffer Object and store it with our vertices glGenBuffers(1, &m_VertexVBO); glBindBuffer(GL_ARRAY_BUFFER, m_VertexVBO); glBufferData(GL_ARRAY_BUFFER, sizeof(Lib3dsVector) * 3 * m_TotalFaces, vertices, GL_STATIC_DRAW); // Generate another Vertex Buffer Object and store the normals in it glGenBuffers(1, &m_NormalVBO); glBindBuffer(GL_ARRAY_BUFFER, m_NormalVBO); glBufferData(GL_ARRAY_BUFFER, sizeof(Lib3dsVector) * 3 * m_TotalFaces, normals, GL_STATIC_DRAW); // Generate a third VBO and store the texture coordinates in it. glGenBuffers(1, &m_TexCoordVBO); glBindBuffer(GL_ARRAY_BUFFER, m_TexCoordVBO); glBufferData(GL_ARRAY_BUFFER, sizeof(Lib3dsTexel) * 3 * m_TotalFaces, texCoords, GL_STATIC_DRAW); // Clean up our allocated memory delete vertices; delete normals; delete texCoords; // We no longer need lib3ds lib3ds_file_free(m_model); m_model = NULL; } void Object::applyTexture(const char*texfilename) { float imageWidth; float imageHeight; glGenTextures(1, & textureObject); // allocate memory for one texture textureObject = SOIL_load_OGL_texture(texfilename,SOIL_LOAD_AUTO,SOIL_CREATE_NEW_ID,SOIL_FLAG_MIPMAPS); glPixelStorei(GL_UNPACK_ALIGNMENT,1); glBindTexture(GL_TEXTURE_2D, textureObject); // use our newest texture glGetTexLevelParameterfv(GL_TEXTURE_2D,0,GL_TEXTURE_WIDTH,&imageWidth); glGetTexLevelParameterfv(GL_TEXTURE_2D,0,GL_TEXTURE_HEIGHT,&imageHeight); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR); // give the best result for texture magnification glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR); //give the best result for texture minification glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP); // don't repeat texture glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP); // don't repeat textureglTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP); // don't repeat texture glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE,GL_MODULATE); glTexImage2D(GL_TEXTURE_2D,0,GL_RGB,imageWidth,imageHeight,0,GL_RGB,GL_UNSIGNED_BYTE,& textureObject); } void Object::Draw() const { // Enable vertex, normal and texture-coordinate arrays. glEnableClientState(GL_VERTEX_ARRAY); glEnableClientState(GL_NORMAL_ARRAY); glEnableClientState(GL_TEXTURE_COORD_ARRAY); // Bind the VBO with the normals. glBindBuffer(GL_ARRAY_BUFFER, m_NormalVBO); // The pointer for the normals is NULL which means that OpenGL will use the currently bound VBO. glNormalPointer(GL_FLOAT, 0, NULL); glBindBuffer(GL_ARRAY_BUFFER, m_TexCoordVBO); glTexCoordPointer(2, GL_FLOAT, 0, NULL); glBindBuffer(GL_ARRAY_BUFFER, m_VertexVBO); glVertexPointer(3, GL_FLOAT, 0, NULL); // Render the triangles. glDrawArrays(GL_TRIANGLES, 0, m_TotalFaces * 3); glDisableClientState(GL_VERTEX_ARRAY); glDisableClientState(GL_NORMAL_ARRAY); glDisableClientState(GL_TEXTURE_COORD_ARRAY); } 3dsloader.h #include "main.h" #include "lib3ds/file.h" #include "lib3ds/mesh.h" #include "lib3ds/material.h" class Object { public: Object(std:: string filename); virtual ~Object(); virtual void Draw() const; virtual void CreateVBO(); void applyTexture(const char*texfilename); protected: void GetFaces(); unsigned int m_TotalFaces; Lib3dsFile * m_model; Lib3dsMesh* Mesh; GLuint textureObject; GLuint m_VertexVBO, m_NormalVBO, m_TexCoordVBO; }; Called in the main cpp file with: VBO,apply texture and draw (pretty simple, how ironic) and thats it, please help me forum :)

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  • Compatibility of Enum Vs. string constants

    - by Yosi
    I was recently told that using Enum: public enum TaskEndState { Error, Completed, Running } may have compatibility/serialization issues, and thus sometimes it's better to use const string: public const string TASK_END_STATE = "END_STATE"; public const string TASK_END_STATE_ERROR = "TASK_END_STATE_ERROR"; public const string TASK_END_STATE_COMPLETE = "TASK_END_STATE_COMPLETE"; public const string TASK_END_STATE_RUNNING = "TASK_END_STATE_RUNNING"; Can you find practical use case where it may happen, is there any guidelines where Enum's should be avoided? Edit: My production environment has multiple WFC services (different versions of the same product). A later version may/or may not include some new properties as Task end state (this is just an example). If we try to deserialize a new Enum value in an older version of a specific service, it may not work.

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  • 2D OBB collision detection, resolving collisions?

    - by Milo
    I currently use OBBs and I have a vehicle that is a rigid body and some buildings. Here is my update() private void update() { camera.setPosition((vehicle.getPosition().x * camera.getScale()) - ((getWidth() ) / 2.0f), (vehicle.getPosition().y * camera.getScale()) - ((getHeight() ) / 2.0f)); //camera.move(input.getAnalogStick().getStickValueX() * 15.0f, input.getAnalogStick().getStickValueY() * 15.0f); if(input.isPressed(ControlButton.BUTTON_GAS)) { vehicle.setThrottle(1.0f, false); } if(input.isPressed(ControlButton.BUTTON_BRAKE)) { vehicle.setBrakes(1.0f); } vehicle.setSteering(input.getAnalogStick().getStickValueX()); vehicle.update(16.6666f / 1000.0f); ArrayList<Building> buildings = city.getBuildings(); for(Building b : buildings) { if(vehicle.getRect().overlaps(b.getRect())) { vehicle.update(-17.0f / 1000.0f); break; } } } The collision detection works well. What doesn't is how they are dealt with. My goal is simple. If the vehicle hits a building, it should stop, and never go into the building. When I apply negative torque to reverse the car should not feel buggy and move away from the building. I don't want this to look buggy. This is my rigid body class: class RigidBody extends Entity { //linear private Vector2D velocity = new Vector2D(); private Vector2D forces = new Vector2D(); private float mass; //angular private float angularVelocity; private float torque; private float inertia; //graphical private Vector2D halfSize = new Vector2D(); private Bitmap image; public RigidBody() { //set these defaults so we don't get divide by zeros mass = 1.0f; inertia = 1.0f; } //intialize out parameters public void initialize(Vector2D halfSize, float mass, Bitmap bitmap) { //store physical parameters this.halfSize = halfSize; this.mass = mass; image = bitmap; inertia = (1.0f / 20.0f) * (halfSize.x * halfSize.x) * (halfSize.y * halfSize.y) * mass; RectF rect = new RectF(); float scalar = 10.0f; rect.left = (int)-halfSize.x * scalar; rect.top = (int)-halfSize.y * scalar; rect.right = rect.left + (int)(halfSize.x * 2.0f * scalar); rect.bottom = rect.top + (int)(halfSize.y * 2.0f * scalar); setRect(rect); } public void setLocation(Vector2D position, float angle) { getRect().set(position, getWidth(), getHeight(), angle); } public Vector2D getPosition() { return getRect().getCenter(); } @Override public void update(float timeStep) { //integrate physics //linear Vector2D acceleration = Vector2D.scalarDivide(forces, mass); velocity = Vector2D.add(velocity, Vector2D.scalarMultiply(acceleration, timeStep)); Vector2D c = getRect().getCenter(); c = Vector2D.add(getRect().getCenter(), Vector2D.scalarMultiply(velocity , timeStep)); setCenter(c.x, c.y); forces = new Vector2D(0,0); //clear forces //angular float angAcc = torque / inertia; angularVelocity += angAcc * timeStep; setAngle(getAngle() + angularVelocity * timeStep); torque = 0; //clear torque } //take a relative Vector2D and make it a world Vector2D public Vector2D relativeToWorld(Vector2D relative) { Matrix mat = new Matrix(); float[] Vector2Ds = new float[2]; Vector2Ds[0] = relative.x; Vector2Ds[1] = relative.y; mat.postRotate(JMath.radToDeg(getAngle())); mat.mapVectors(Vector2Ds); return new Vector2D(Vector2Ds[0], Vector2Ds[1]); } //take a world Vector2D and make it a relative Vector2D public Vector2D worldToRelative(Vector2D world) { Matrix mat = new Matrix(); float[] Vectors = new float[2]; Vectors[0] = world.x; Vectors[1] = world.y; mat.postRotate(JMath.radToDeg(-getAngle())); mat.mapVectors(Vectors); return new Vector2D(Vectors[0], Vectors[1]); } //velocity of a point on body public Vector2D pointVelocity(Vector2D worldOffset) { Vector2D tangent = new Vector2D(-worldOffset.y, worldOffset.x); return Vector2D.add( Vector2D.scalarMultiply(tangent, angularVelocity) , velocity); } public void applyForce(Vector2D worldForce, Vector2D worldOffset) { //add linear force forces = Vector2D.add(forces ,worldForce); //add associated torque torque += Vector2D.cross(worldOffset, worldForce); } @Override public void draw( GraphicsContext c) { c.drawRotatedScaledBitmap(image, getPosition().x, getPosition().y, getWidth(), getHeight(), getAngle()); } } Essentially, when any rigid body hits a building it should exhibit the same behavior. How is collision solving usually done? Thanks

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  • Accessing the same service more than twice in the nick of time

    - by PointedC
    I have an application that will access interface service A which is to run from windows startup. This service is used by program B and my application functions on B's presence after getting a pointer to A. The scenario is translated as follows, public interface A{} ///my program public class MyProgram { public MyProgram() { ProgramB.DoA(); } public A GetA(){} } public class ProgramB { void DoA(){} } The translated source is not true, but that seems to be what I am looking for. In order to eliminate the overhead of allocating and realocating dynamic accesses to the same service used by other processes, would you please provide an actual solution to the problem ?(I am all out of any idea now)

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  • Subterranean IL: Exception handler semantics

    - by Simon Cooper
    In my blog posts on fault and filter exception handlers, I said that the same behaviour could be replicated using normal catch blocks. Well, that isn't entirely true... Changing the handler semantics Consider the following: .try { .try { .try { newobj instance void [mscorlib]System.Exception::.ctor() // IL for: // e.Data.Add("DictKey", true) throw } fault { ldstr "1: Fault handler" call void [mscorlib]System.Console::WriteLine(string) endfault } } filter { ldstr "2a: Filter logic" call void [mscorlib]System.Console::WriteLine(string) // IL for: // (bool)((Exception)e).Data["DictKey"] endfilter }{ ldstr "2b: Filter handler" call void [mscorlib]System.Console::WriteLine(string) leave.s Return } } catch object { ldstr "3: Catch handler" call void [mscorlib]System.Console::WriteLine(string) leave.s Return } Return: // rest of method If the filter handler is engaged (true is inserted into the exception dictionary) then the filter handler gets engaged, and the following gets printed to the console: 2a: Filter logic 1: Fault handler 2b: Filter handler and if the filter handler isn't engaged, then the following is printed: 2a:Filter logic 1: Fault handler 3: Catch handler Filter handler execution The filter handler is executed first. Hmm, ok. Well, what happens if we replaced the fault block with the C# equivalent (with the exception dictionary value set to false)? .try { // throw exception } catch object { ldstr "1: Fault handler" call void [mscorlib]System.Console::WriteLine(string) rethrow } we get this: 1: Fault handler 2a: Filter logic 3: Catch handler The fault handler is executed first, instead of the filter block. Eh? This change in behaviour is due to the way the CLR searches for exception handlers. When an exception is thrown, the CLR stops execution of the thread, and searches up the stack for an exception handler that can handle the exception and stop it propagating further - catch or filter handlers. It checks the type clause of catch clauses, and executes the code in filter blocks to see if the filter can handle the exception. When the CLR finds a valid handler, it saves the handler's location, then goes back to where the exception was thrown and executes fault and finally blocks between there and the handler location, discarding stack frames in the process, until it reaches the handler. So? By replacing a fault with a catch, we have changed the semantics of when the filter code is executed; by using a rethrow instruction, we've split up the exception handler search into two - one search to find the first catch, then a second when the rethrow instruction is encountered. This is only really obvious when mixing C# exception handlers with fault or filter handlers, so this doesn't affect code written only in C#. However it could cause some subtle and hard-to-debug effects with object initialization and ordering when using and calling code written in a language that can compile fault and filter handlers.

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  • Creating java package on ubuntu?

    - by Gaurav_Java
    I am new to java. Here I am trying to create java package. And try to compile it from another directory . But there is an error like bash: /home/gaurav/Desktop/package2/B.java: Permission denied Here is fy first code and directory is /home/Desktop/package/A.java package package1; public class A { interface A1 { void show(); void display(); } } class B extends A { public void show() { System.out.println("This is show method()"); } public void display() { System.out.println("this is Display metthod()"); } } For compilation I did this command it's works fine. pwd is /home/gaurav javac /home/gaurav/Desktop/package/A.java When I try to compile B.java which is in my Other drive /media/gaurav/iPlay/package/B.java package package2; class B { public static void main(String args[]) { System.out.println("Reached in Main method of B"); package1.A Object = new A(); } } I tired this vommand (grom previous working directory) javac -cp /home/gaurav/Desktop/;/media/gaurav/iPlay/package/B.java Error Comes javac -cp /home/gaurav/Desktop/;/media/gaurav/iPlay/package/B.java javac: no source files Usage: javac <options> <source files> use -help for a list of possible options bash: /media/gaurav/iPlay/package/B.java: Permission denied What i am doing wrong? Please it my assignment I am not able to move further without this. I changed permissions.

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  • Implementing separation of concerns via MVC

    - by user2368481
    I'm creating a question to see if my understanding of MVC separation is correct, I haven't been able to find a clear answer anywhere online. So is this the right way to implement it (in Java): I would have 3 .java files, one each for Model, Controller, View. I would put all the classes related to Model in the Model.java like so: //Model.java { public class Model //class fields public Model(); public ModelClassA(); public ModelClassB(); public ModelClassC(); } With the ModelClasses being any class that I consider belonging to the Model. Is it correct to have the classes within the Model Class, as I have read that nested classes should be avoided where possible.

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  • C#/.NET Little Wonders: The Generic Func Delegates

    - by James Michael Hare
    Once again, in this series of posts I look at the parts of the .NET Framework that may seem trivial, but can help improve your code by making it easier to write and maintain. The index of all my past little wonders posts can be found here. Back in one of my three original “Little Wonders” Trilogy of posts, I had listed generic delegates as one of the Little Wonders of .NET.  Later, someone posted a comment saying said that they would love more detail on the generic delegates and their uses, since my original entry just scratched the surface of them. Last week, I began our look at some of the handy generic delegates built into .NET with a description of delegates in general, and the Action family of delegates.  For this week, I’ll launch into a look at the Func family of generic delegates and how they can be used to support generic, reusable algorithms and classes. Quick Delegate Recap Delegates are similar to function pointers in C++ in that they allow you to store a reference to a method.  They can store references to either static or instance methods, and can actually be used to chain several methods together in one delegate. Delegates are very type-safe and can be satisfied with any standard method, anonymous method, or a lambda expression.  They can also be null as well (refers to no method), so care should be taken to make sure that the delegate is not null before you invoke it. Delegates are defined using the keyword delegate, where the delegate’s type name is placed where you would typically place the method name: 1: // This delegate matches any method that takes string, returns nothing 2: public delegate void Log(string message); This delegate defines a delegate type named Log that can be used to store references to any method(s) that satisfies its signature (whether instance, static, lambda expression, etc.). Delegate instances then can be assigned zero (null) or more methods using the operator = which replaces the existing delegate chain, or by using the operator += which adds a method to the end of a delegate chain: 1: // creates a delegate instance named currentLogger defaulted to Console.WriteLine (static method) 2: Log currentLogger = Console.Out.WriteLine; 3:  4: // invokes the delegate, which writes to the console out 5: currentLogger("Hi Standard Out!"); 6:  7: // append a delegate to Console.Error.WriteLine to go to std error 8: currentLogger += Console.Error.WriteLine; 9:  10: // invokes the delegate chain and writes message to std out and std err 11: currentLogger("Hi Standard Out and Error!"); While delegates give us a lot of power, it can be cumbersome to re-create fairly standard delegate definitions repeatedly, for this purpose the generic delegates were introduced in various stages in .NET.  These support various method types with particular signatures. Note: a caveat with generic delegates is that while they can support multiple parameters, they do not match methods that contains ref or out parameters. If you want to a delegate to represent methods that takes ref or out parameters, you will need to create a custom delegate. We’ve got the Func… delegates Just like it’s cousin, the Action delegate family, the Func delegate family gives us a lot of power to use generic delegates to make classes and algorithms more generic.  Using them keeps us from having to define a new delegate type when need to make a class or algorithm generic. Remember that the point of the Action delegate family was to be able to perform an “action” on an item, with no return results.  Thus Action delegates can be used to represent most methods that take 0 to 16 arguments but return void.  You can assign a method The Func delegate family was introduced in .NET 3.5 with the advent of LINQ, and gives us the power to define a function that can be called on 0 to 16 arguments and returns a result.  Thus, the main difference between Action and Func, from a delegate perspective, is that Actions return nothing, but Funcs return a result. The Func family of delegates have signatures as follows: Func<TResult> – matches a method that takes no arguments, and returns value of type TResult. Func<T, TResult> – matches a method that takes an argument of type T, and returns value of type TResult. Func<T1, T2, TResult> – matches a method that takes arguments of type T1 and T2, and returns value of type TResult. Func<T1, T2, …, TResult> – and so on up to 16 arguments, and returns value of type TResult. These are handy because they quickly allow you to be able to specify that a method or class you design will perform a function to produce a result as long as the method you specify meets the signature. For example, let’s say you were designing a generic aggregator, and you wanted to allow the user to define how the values will be aggregated into the result (i.e. Sum, Min, Max, etc…).  To do this, we would ask the user of our class to pass in a method that would take the current total, the next value, and produce a new total.  A class like this could look like: 1: public sealed class Aggregator<TValue, TResult> 2: { 3: // holds method that takes previous result, combines with next value, creates new result 4: private Func<TResult, TValue, TResult> _aggregationMethod; 5:  6: // gets or sets the current result of aggregation 7: public TResult Result { get; private set; } 8:  9: // construct the aggregator given the method to use to aggregate values 10: public Aggregator(Func<TResult, TValue, TResult> aggregationMethod = null) 11: { 12: if (aggregationMethod == null) throw new ArgumentNullException("aggregationMethod"); 13:  14: _aggregationMethod = aggregationMethod; 15: } 16:  17: // method to add next value 18: public void Aggregate(TValue nextValue) 19: { 20: // performs the aggregation method function on the current result and next and sets to current result 21: Result = _aggregationMethod(Result, nextValue); 22: } 23: } Of course, LINQ already has an Aggregate extension method, but that works on a sequence of IEnumerable<T>, whereas this is designed to work more with aggregating single results over time (such as keeping track of a max response time for a service). We could then use this generic aggregator to find the sum of a series of values over time, or the max of a series of values over time (among other things): 1: // creates an aggregator that adds the next to the total to sum the values 2: var sumAggregator = new Aggregator<int, int>((total, next) => total + next); 3:  4: // creates an aggregator (using static method) that returns the max of previous result and next 5: var maxAggregator = new Aggregator<int, int>(Math.Max); So, if we were timing the response time of a web method every time it was called, we could pass that response time to both of these aggregators to get an idea of the total time spent in that web method, and the max time spent in any one call to the web method: 1: // total will be 13 and max 13 2: int responseTime = 13; 3: sumAggregator.Aggregate(responseTime); 4: maxAggregator.Aggregate(responseTime); 5:  6: // total will be 20 and max still 13 7: responseTime = 7; 8: sumAggregator.Aggregate(responseTime); 9: maxAggregator.Aggregate(responseTime); 10:  11: // total will be 40 and max now 20 12: responseTime = 20; 13: sumAggregator.Aggregate(responseTime); 14: maxAggregator.Aggregate(responseTime); The Func delegate family is useful for making generic algorithms and classes, and in particular allows the caller of the method or user of the class to specify a function to be performed in order to generate a result. What is the result of a Func delegate chain? If you remember, we said earlier that you can assign multiple methods to a delegate by using the += operator to chain them.  So how does this affect delegates such as Func that return a value, when applied to something like the code below? 1: Func<int, int, int> combo = null; 2:  3: // What if we wanted to aggregate the sum and max together? 4: combo += (total, next) => total + next; 5: combo += Math.Max; 6:  7: // what is the result? 8: var comboAggregator = new Aggregator<int, int>(combo); Well, in .NET if you chain multiple methods in a delegate, they will all get invoked, but the result of the delegate is the result of the last method invoked in the chain.  Thus, this aggregator would always result in the Math.Max() result.  The other chained method (the sum) gets executed first, but it’s result is thrown away: 1: // result is 13 2: int responseTime = 13; 3: comboAggregator.Aggregate(responseTime); 4:  5: // result is still 13 6: responseTime = 7; 7: comboAggregator.Aggregate(responseTime); 8:  9: // result is now 20 10: responseTime = 20; 11: comboAggregator.Aggregate(responseTime); So remember, you can chain multiple Func (or other delegates that return values) together, but if you do so you will only get the last executed result. Func delegates and co-variance/contra-variance in .NET 4.0 Just like the Action delegate, as of .NET 4.0, the Func delegate family is contra-variant on its arguments.  In addition, it is co-variant on its return type.  To support this, in .NET 4.0 the signatures of the Func delegates changed to: Func<out TResult> – matches a method that takes no arguments, and returns value of type TResult (or a more derived type). Func<in T, out TResult> – matches a method that takes an argument of type T (or a less derived type), and returns value of type TResult(or a more derived type). Func<in T1, in T2, out TResult> – matches a method that takes arguments of type T1 and T2 (or less derived types), and returns value of type TResult (or a more derived type). Func<in T1, in T2, …, out TResult> – and so on up to 16 arguments, and returns value of type TResult (or a more derived type). Notice the addition of the in and out keywords before each of the generic type placeholders.  As we saw last week, the in keyword is used to specify that a generic type can be contra-variant -- it can match the given type or a type that is less derived.  However, the out keyword, is used to specify that a generic type can be co-variant -- it can match the given type or a type that is more derived. On contra-variance, if you are saying you need an function that will accept a string, you can just as easily give it an function that accepts an object.  In other words, if you say “give me an function that will process dogs”, I could pass you a method that will process any animal, because all dogs are animals.  On the co-variance side, if you are saying you need a function that returns an object, you can just as easily pass it a function that returns a string because any string returned from the given method can be accepted by a delegate expecting an object result, since string is more derived.  Once again, in other words, if you say “give me a method that creates an animal”, I can pass you a method that will create a dog, because all dogs are animals. It really all makes sense, you can pass a more specific thing to a less specific parameter, and you can return a more specific thing as a less specific result.  In other words, pay attention to the direction the item travels (parameters go in, results come out).  Keeping that in mind, you can always pass more specific things in and return more specific things out. For example, in the code below, we have a method that takes a Func<object> to generate an object, but we can pass it a Func<string> because the return type of object can obviously accept a return value of string as well: 1: // since Func<object> is co-variant, this will access Func<string>, etc... 2: public static string Sequence(int count, Func<object> generator) 3: { 4: var builder = new StringBuilder(); 5:  6: for (int i=0; i<count; i++) 7: { 8: object value = generator(); 9: builder.Append(value); 10: } 11:  12: return builder.ToString(); 13: } Even though the method above takes a Func<object>, we can pass a Func<string> because the TResult type placeholder is co-variant and accepts types that are more derived as well: 1: // delegate that's typed to return string. 2: Func<string> stringGenerator = () => DateTime.Now.ToString(); 3:  4: // This will work in .NET 4.0, but not in previous versions 5: Sequence(100, stringGenerator); Previous versions of .NET implemented some forms of co-variance and contra-variance before, but .NET 4.0 goes one step further and allows you to pass or assign an Func<A, BResult> to a Func<Y, ZResult> as long as A is less derived (or same) as Y, and BResult is more derived (or same) as ZResult. Sidebar: The Func and the Predicate A method that takes one argument and returns a bool is generally thought of as a predicate.  Predicates are used to examine an item and determine whether that item satisfies a particular condition.  Predicates are typically unary, but you may also have binary and other predicates as well. Predicates are often used to filter results, such as in the LINQ Where() extension method: 1: var numbers = new[] { 1, 2, 4, 13, 8, 10, 27 }; 2:  3: // call Where() using a predicate which determines if the number is even 4: var evens = numbers.Where(num => num % 2 == 0); As of .NET 3.5, predicates are typically represented as Func<T, bool> where T is the type of the item to examine.  Previous to .NET 3.5, there was a Predicate<T> type that tended to be used (which we’ll discuss next week) and is still supported, but most developers recommend using Func<T, bool> now, as it prevents confusion with overloads that accept unary predicates and binary predicates, etc.: 1: // this seems more confusing as an overload set, because of Predicate vs Func 2: public static SomeMethod(Predicate<int> unaryPredicate) { } 3: public static SomeMethod(Func<int, int, bool> binaryPredicate) { } 4:  5: // this seems more consistent as an overload set, since just uses Func 6: public static SomeMethod(Func<int, bool> unaryPredicate) { } 7: public static SomeMethod(Func<int, int, bool> binaryPredicate) { } Also, even though Predicate<T> and Func<T, bool> match the same signatures, they are separate types!  Thus you cannot assign a Predicate<T> instance to a Func<T, bool> instance and vice versa: 1: // the same method, lambda expression, etc can be assigned to both 2: Predicate<int> isEven = i => (i % 2) == 0; 3: Func<int, bool> alsoIsEven = i => (i % 2) == 0; 4:  5: // but the delegate instances cannot be directly assigned, strongly typed! 6: // ERROR: cannot convert type... 7: isEven = alsoIsEven; 8:  9: // however, you can assign by wrapping in a new instance: 10: isEven = new Predicate<int>(alsoIsEven); 11: alsoIsEven = new Func<int, bool>(isEven); So, the general advice that seems to come from most developers is that Predicate<T> is still supported, but we should use Func<T, bool> for consistency in .NET 3.5 and above. Sidebar: Func as a Generator for Unit Testing One area of difficulty in unit testing can be unit testing code that is based on time of day.  We’d still want to unit test our code to make sure the logic is accurate, but we don’t want the results of our unit tests to be dependent on the time they are run. One way (of many) around this is to create an internal generator that will produce the “current” time of day.  This would default to returning result from DateTime.Now (or some other method), but we could inject specific times for our unit testing.  Generators are typically methods that return (generate) a value for use in a class/method. For example, say we are creating a CacheItem<T> class that represents an item in the cache, and we want to make sure the item shows as expired if the age is more than 30 seconds.  Such a class could look like: 1: // responsible for maintaining an item of type T in the cache 2: public sealed class CacheItem<T> 3: { 4: // helper method that returns the current time 5: private static Func<DateTime> _timeGenerator = () => DateTime.Now; 6:  7: // allows internal access to the time generator 8: internal static Func<DateTime> TimeGenerator 9: { 10: get { return _timeGenerator; } 11: set { _timeGenerator = value; } 12: } 13:  14: // time the item was cached 15: public DateTime CachedTime { get; private set; } 16:  17: // the item cached 18: public T Value { get; private set; } 19:  20: // item is expired if older than 30 seconds 21: public bool IsExpired 22: { 23: get { return _timeGenerator() - CachedTime > TimeSpan.FromSeconds(30.0); } 24: } 25:  26: // creates the new cached item, setting cached time to "current" time 27: public CacheItem(T value) 28: { 29: Value = value; 30: CachedTime = _timeGenerator(); 31: } 32: } Then, we can use this construct to unit test our CacheItem<T> without any time dependencies: 1: var baseTime = DateTime.Now; 2:  3: // start with current time stored above (so doesn't drift) 4: CacheItem<int>.TimeGenerator = () => baseTime; 5:  6: var target = new CacheItem<int>(13); 7:  8: // now add 15 seconds, should still be non-expired 9: CacheItem<int>.TimeGenerator = () => baseTime.AddSeconds(15); 10:  11: Assert.IsFalse(target.IsExpired); 12:  13: // now add 31 seconds, should now be expired 14: CacheItem<int>.TimeGenerator = () => baseTime.AddSeconds(31); 15:  16: Assert.IsTrue(target.IsExpired); Now we can unit test for 1 second before, 1 second after, 1 millisecond before, 1 day after, etc.  Func delegates can be a handy tool for this type of value generation to support more testable code.  Summary Generic delegates give us a lot of power to make truly generic algorithms and classes.  The Func family of delegates is a great way to be able to specify functions to calculate a result based on 0-16 arguments.  Stay tuned in the weeks that follow for other generic delegates in the .NET Framework!   Tweet Technorati Tags: .NET, C#, CSharp, Little Wonders, Generics, Func, Delegates

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  • Constant game speed independent of variable FPS in OpenGL with GLUT?

    - by Nazgulled
    I've been reading Koen Witters detailed article about different game loop solutions but I'm having some problems implementing the last one with GLUT, which is the recommended one. After reading a couple of articles, tutorials and code from other people on how to achieve a constant game speed, I think that what I currently have implemented (I'll post the code below) is what Koen Witters called Game Speed dependent on Variable FPS, the second on his article. First, through my searching experience, there's a couple of people that probably have the knowledge to help out on this but don't know what GLUT is and I'm going to try and explain (feel free to correct me) the relevant functions for my problem of this OpenGL toolkit. Skip this section if you know what GLUT is and how to play with it. GLUT Toolkit: GLUT is an OpenGL toolkit and helps with common tasks in OpenGL. The glutDisplayFunc(renderScene) takes a pointer to a renderScene() function callback, which will be responsible for rendering everything. The renderScene() function will only be called once after the callback registration. The glutTimerFunc(TIMER_MILLISECONDS, processAnimationTimer, 0) takes the number of milliseconds to pass before calling the callback processAnimationTimer(). The last argument is just a value to pass to the timer callback. The processAnimationTimer() will not be called each TIMER_MILLISECONDS but just once. The glutPostRedisplay() function requests GLUT to render a new frame so we need call this every time we change something in the scene. The glutIdleFunc(renderScene) could be used to register a callback to renderScene() (this does not make glutDisplayFunc() irrelevant) but this function should be avoided because the idle callback is continuously called when events are not being received, increasing the CPU load. The glutGet(GLUT_ELAPSED_TIME) function returns the number of milliseconds since glutInit was called (or first call to glutGet(GLUT_ELAPSED_TIME)). That's the timer we have with GLUT. I know there are better alternatives for high resolution timers, but let's keep with this one for now. I think this is enough information on how GLUT renders frames so people that didn't know about it could also pitch in this question to try and help if they fell like it. Current Implementation: Now, I'm not sure I have correctly implemented the second solution proposed by Koen, Game Speed dependent on Variable FPS. The relevant code for that goes like this: #define TICKS_PER_SECOND 30 #define MOVEMENT_SPEED 2.0f const int TIMER_MILLISECONDS = 1000 / TICKS_PER_SECOND; int previousTime; int currentTime; int elapsedTime; void renderScene(void) { (...) // Setup the camera position and looking point SceneCamera.LookAt(); // Do all drawing below... (...) } void processAnimationTimer(int value) { // setups the timer to be called again glutTimerFunc(TIMER_MILLISECONDS, processAnimationTimer, 0); // Get the time when the previous frame was rendered previousTime = currentTime; // Get the current time (in milliseconds) and calculate the elapsed time currentTime = glutGet(GLUT_ELAPSED_TIME); elapsedTime = currentTime - previousTime; /* Multiply the camera direction vector by constant speed then by the elapsed time (in seconds) and then move the camera */ SceneCamera.Move(cameraDirection * MOVEMENT_SPEED * (elapsedTime / 1000.0f)); // Requests to render a new frame (this will call my renderScene() once) glutPostRedisplay(); } void main(int argc, char **argv) { glutInit(&argc, argv); (...) glutDisplayFunc(renderScene); (...) // Setup the timer to be called one first time glutTimerFunc(TIMER_MILLISECONDS, processAnimationTimer, 0); // Read the current time since glutInit was called currentTime = glutGet(GLUT_ELAPSED_TIME); glutMainLoop(); } This implementation doesn't fell right. It works in the sense that helps the game speed to be constant dependent on the FPS. So that moving from point A to point B takes the same time no matter the high/low framerate. However, I believe I'm limiting the game framerate with this approach. Each frame will only be rendered when the time callback is called, that means the framerate will be roughly around TICKS_PER_SECOND frames per second. This doesn't feel right, you shouldn't limit your powerful hardware, it's wrong. It's my understanding though, that I still need to calculate the elapsedTime. Just because I'm telling GLUT to call the timer callback every TIMER_MILLISECONDS, it doesn't mean it will always do that on time. I'm not sure how can I fix this and to be completely honest, I have no idea what is the game loop in GLUT, you know, the while( game_is_running ) loop in Koen's article. But it's my understanding that GLUT is event-driven and that game loop starts when I call glutMainLoop() (which never returns), yes? I thought I could register an idle callback with glutIdleFunc() and use that as replacement of glutTimerFunc(), only rendering when necessary (instead of all the time as usual) but when I tested this with an empty callback (like void gameLoop() {}) and it was basically doing nothing, only a black screen, the CPU spiked to 25% and remained there until I killed the game and it went back to normal. So I don't think that's the path to follow. Using glutTimerFunc() is definitely not a good approach to perform all movements/animations based on that, as I'm limiting my game to a constant FPS, not cool. Or maybe I'm using it wrong and my implementation is not right? How exactly can I have a constant game speed with variable FPS? More exactly, how do I correctly implement Koen's Constant Game Speed with Maximum FPS solution (the fourth one on his article) with GLUT? Maybe this is not possible at all with GLUT? If not, what are my alternatives? What is the best approach to this problem (constant game speed) with GLUT? I originally posted this question on Stack Overflow before being pointed out about this site. The following is a different approach I tried after creating the question in SO, so I'm posting it here too. Another Approach: I've been experimenting and here's what I was able to achieve now. Instead of calculating the elapsed time on a timed function (which limits my game's framerate) I'm now doing it in renderScene(). Whenever changes to the scene happen I call glutPostRedisplay() (ie: camera moving, some object animation, etc...) which will make a call to renderScene(). I can use the elapsed time in this function to move my camera for instance. My code has now turned into this: int previousTime; int currentTime; int elapsedTime; void renderScene(void) { (...) // Setup the camera position and looking point SceneCamera.LookAt(); // Do all drawing below... (...) } void renderScene(void) { (...) // Get the time when the previous frame was rendered previousTime = currentTime; // Get the current time (in milliseconds) and calculate the elapsed time currentTime = glutGet(GLUT_ELAPSED_TIME); elapsedTime = currentTime - previousTime; /* Multiply the camera direction vector by constant speed then by the elapsed time (in seconds) and then move the camera */ SceneCamera.Move(cameraDirection * MOVEMENT_SPEED * (elapsedTime / 1000.0f)); // Setup the camera position and looking point SceneCamera.LookAt(); // All drawing code goes inside this function drawCompleteScene(); glutSwapBuffers(); /* Redraw the frame ONLY if the user is moving the camera (similar code will be needed to redraw the frame for other events) */ if(!IsTupleEmpty(cameraDirection)) { glutPostRedisplay(); } } void main(int argc, char **argv) { glutInit(&argc, argv); (...) glutDisplayFunc(renderScene); (...) currentTime = glutGet(GLUT_ELAPSED_TIME); glutMainLoop(); } Conclusion, it's working, or so it seems. If I don't move the camera, the CPU usage is low, nothing is being rendered (for testing purposes I only have a grid extending for 4000.0f, while zFar is set to 1000.0f). When I start moving the camera the scene starts redrawing itself. If I keep pressing the move keys, the CPU usage will increase; this is normal behavior. It drops back when I stop moving. Unless I'm missing something, it seems like a good approach for now. I did find this interesting article on iDevGames and this implementation is probably affected by the problem described on that article. What's your thoughts on that? Please note that I'm just doing this for fun, I have no intentions of creating some game to distribute or something like that, not in the near future at least. If I did, I would probably go with something else besides GLUT. But since I'm using GLUT, and other than the problem described on iDevGames, do you think this latest implementation is sufficient for GLUT? The only real issue I can think of right now is that I'll need to keep calling glutPostRedisplay() every time the scene changes something and keep calling it until there's nothing new to redraw. A little complexity added to the code for a better cause, I think. What do you think?

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  • C#/.NET Little Wonders &ndash; Cross Calling Constructors

    - by James Michael Hare
    Just a small post today, it’s the final iteration before our release and things are crazy here!  This is another little tidbit that I love using, and it should be fairly common knowledge, yet I’ve noticed many times that less experienced developers tend to have redundant constructor code when they overload their constructors. The Problem – repetitive code is less maintainable Let’s say you were designing a messaging system, and so you want to create a class to represent the properties for a Receiver, so perhaps you design a ReceiverProperties class to represent this collection of properties. Perhaps, you decide to make ReceiverProperties immutable, and so you have several constructors that you can use for alternative construction: 1: // Constructs a set of receiver properties. 2: public ReceiverProperties(ReceiverType receiverType, string source, bool isDurable, bool isBuffered) 3: { 4: ReceiverType = receiverType; 5: Source = source; 6: IsDurable = isDurable; 7: IsBuffered = isBuffered; 8: } 9: 10: // Constructs a set of receiver properties with buffering on by default. 11: public ReceiverProperties(ReceiverType receiverType, string source, bool isDurable) 12: { 13: ReceiverType = receiverType; 14: Source = source; 15: IsDurable = isDurable; 16: IsBuffered = true; 17: } 18:  19: // Constructs a set of receiver properties with buffering on and durability off. 20: public ReceiverProperties(ReceiverType receiverType, string source) 21: { 22: ReceiverType = receiverType; 23: Source = source; 24: IsDurable = false; 25: IsBuffered = true; 26: } Note: keep in mind this is just a simple example for illustration, and in same cases default parameters can also help clean this up, but they have issues of their own. While strictly speaking, there is nothing wrong with this code, logically, it suffers from maintainability flaws.  Consider what happens if you add a new property to the class?  You have to remember to guarantee that it is set appropriately in every constructor call. This can cause subtle bugs and becomes even uglier when the constructors do more complex logic, error handling, or there are numerous potential overloads (especially if you can’t easily see them all on one screen’s height). The Solution – cross-calling constructors I’d wager nearly everyone knows how to call your base class’s constructor, but you can also cross-call to one of the constructors in the same class by using the this keyword in the same way you use base to call a base constructor. 1: // Constructs a set of receiver properties. 2: public ReceiverProperties(ReceiverType receiverType, string source, bool isDurable, bool isBuffered) 3: { 4: ReceiverType = receiverType; 5: Source = source; 6: IsDurable = isDurable; 7: IsBuffered = isBuffered; 8: } 9: 10: // Constructs a set of receiver properties with buffering on by default. 11: public ReceiverProperties(ReceiverType receiverType, string source, bool isDurable) 12: : this(receiverType, source, isDurable, true) 13: { 14: } 15:  16: // Constructs a set of receiver properties with buffering on and durability off. 17: public ReceiverProperties(ReceiverType receiverType, string source) 18: : this(receiverType, source, false, true) 19: { 20: } Notice, there is much less code.  In addition, the code you have has no repetitive logic.  You can define the main constructor that takes all arguments, and the remaining constructors with defaults simply cross-call the main constructor, passing in the defaults. Yes, in some cases default parameters can ease some of this for you, but default parameters only work for compile-time constants (null, string and number literals).  For example, if you were creating a TradingDataAdapter that relied on an implementation of ITradingDao which is the data access object to retreive records from the database, you might want two constructors: one that takes an ITradingDao reference, and a default constructor which constructs a specific ITradingDao for ease of use: 1: public TradingDataAdapter(ITradingDao dao) 2: { 3: _tradingDao = dao; 4:  5: // other constructor logic 6: } 7:  8: public TradingDataAdapter() 9: { 10: _tradingDao = new SqlTradingDao(); 11:  12: // same constructor logic as above 13: }   As you can see, this isn’t something we can solve with a default parameter, but we could with cross-calling constructors: 1: public TradingDataAdapter(ITradingDao dao) 2: { 3: _tradingDao = dao; 4:  5: // other constructor logic 6: } 7:  8: public TradingDataAdapter() 9: : this(new SqlTradingDao()) 10: { 11: }   So in cases like this where you have constructors with non compiler-time constant defaults, default parameters can’t help you and cross-calling constructors is one of your best options. Summary When you have just one constructor doing the job of initializing the class, you can consolidate all your logic and error-handling in one place, thus ensuring that your behavior will be consistent across the constructor calls. This makes the code more maintainable and even easier to read.  There will be some cases where cross-calling constructors may be sub-optimal or not possible (if, for example, the overloaded constructors take completely different types and are not just “defaulting” behaviors). You can also use default parameters, of course, but default parameter behavior in a class hierarchy can be problematic (default values are not inherited and in fact can differ) so sometimes multiple constructors are actually preferable. Regardless of why you may need to have multiple constructors, consider cross-calling where you can to reduce redundant logic and clean up the code.   Technorati Tags: C#,.NET,Little Wonders

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  • How to unicode Myanmar texts on Java? [closed]

    - by Spacez Ly Wang
    I'm just beginner of Java. I'm trying to unicode (display) correctly Myanmar texts on Java GUI ( Swing/Awt ). I have four TrueType fonts which support Myanmar unicode texts. There are Myanmar3, Padauk, Tharlon, Myanmar Text ( Window 8 built-in ). You may need the fonts before the code. Google the fonts, please. Each of the fonts display on Java GUI differently and incorrectly. Here is the code for GUI Label displaying myanmar texts: ++++++++++++++++++++++++ package javaapplication1; import javax.swing.JFrame; import javax.swing.JTextField; public class CusFrom { private static void createAndShowGUI() { JFrame frame = new JFrame("Hello World Swing"); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); String s = "\u1015\u102F \u103C\u1015\u102F"; JLabel label = new JLabel(s); label.setFont(new java.awt.Font("Myanmar3", 0, 20));// font insert here, Myanmar Text, Padauk, Myanmar3, Tharlon frame.getContentPane().add(label); frame.pack(); frame.setVisible(true); } public static void main(String[] args) { javax.swing.SwingUtilities.invokeLater(new Runnable() { public void run() { createAndShowGUI(); } }); } } ++++++++++++++++++++++++ Outputs vary. See the pictures: Myanmar3 IMG Padauk IMG Tharlon IMG Myanmar Text IMG What is the correct form? (on notepad) Well, next is the code for GUI Textfield inputting Myanmar texts: ++++++++++++++++++++++++ package javaapplication1; import javax.swing.JFrame; import javax.swing.JTextField; public class XusForm { private static void createAndShowGUI() { JFrame frame = new JFrame("Frame Title"); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); JTextField textfield = new JTextField(); textfield.setFont(new java.awt.Font("Myanmar3", 0, 20)); frame.getContentPane().add(textfield); frame.pack(); frame.setVisible(true); } public static void main(String[] args) { javax.swing.SwingUtilities.invokeLater(new Runnable() { public void run() { createAndShowGUI(); } }); } } ++++++++++++++++++++++++ Outputs vary when I input keys( unicode text ) on keyboards. Myanmar Text Output IMG Padauk Output IMG Myanmar3 Output IMG Tharlon Output IMG Those fonts work well on Linux when opening text files with Text Editor application. My Question is how to unicode Myanmar texts on Java GUI. Do I need additional codes left to display well? Or Does Java still have errors? The fonts display well on Web Application (HTML, CSS) but I'm not sure about displaying on Java Web Application.

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  • Java regex patterns - compile time constants or instance members?

    - by KepaniHaole
    Currently, I have a couple of singleton objects where I'm doing matching on regular expressions, and my Patterns are defined like so: class Foobar { private final Pattern firstPattern = Pattern.compile("some regex"); private final Pattern secondPattern = Pattern.compile("some other regex"); // more Patterns, etc. private Foobar() {} public static Foobar create() { /* singleton stuff */ } } But I was told by someone the other day that this is bad style, and Patterns should always be defined at the class level, and look something like this instead: class Foobar { private static final Pattern FIRST_PATTERN = Pattern.compile("some regex"); private static final Pattern SECOND_PATTERN = Pattern.compile("some other regex"); // more Patterns, etc. private Foobar() {} public static Foobar create() { /* singleton stuff */ } } The lifetime of this particular object isn't that long, and my main reason for using the first approach is because it doesn't make sense to me to hold on to the Patterns once the object gets GC'd. Any suggestions / thoughts?

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