Search Results

Search found 29467 results on 1179 pages for 'public'.

Page 196/1179 | < Previous Page | 192 193 194 195 196 197 198 199 200 201 202 203  | Next Page >

• Refactor This (Ugly Code)!

  - by Alois Kraus

  Ayende has put on his blog some ugly code to refactor. First and foremost it is nearly impossible to reason about other peoples code without knowing the driving forces behind the current code. It is certainly possible to make it much cleaner when potential sources of errors cannot happen in the first place due to good design. I can see what the intention of the code is but I do not know about every brittle detail if I am allowed to reorder things here and there to simplify things. So I decided to make it much simpler by identifying the different responsibilities of the methods and encapsulate it in different classes. The code we need to refactor seems to deal with a handler after a message has been sent to a message queue. The handler does complete the current transaction if there is any and does handle any errors happening there. If during the the completion of the transaction errors occur the transaction is at least disposed. We can enter the handler already in a faulty state where we try to deliver the complete event in any case and signal a failure event and try to resend the message again to the queue if it was not inside a transaction. All is decorated with many try/catch blocks, duplicated code and some state variables to route the program flow. It is hard to understand and difficult to reason about. In other words: This code is a mess and could be written by me if I was under pressure. Here comes to code we want to refactor:         private void HandleMessageCompletion(                                      Message message,                                      TransactionScope tx,                                      OpenedQueue messageQueue,                                      Exception exception,                                      Action<CurrentMessageInformation, Exception> messageCompleted,                                      Action<CurrentMessageInformation> beforeTransactionCommit)         {             var txDisposed = false;             if (exception == null)             {                 try                 {                     if (tx != null)                     {                         if (beforeTransactionCommit != null)                             beforeTransactionCommit(currentMessageInformation);                         tx.Complete();                         tx.Dispose();                         txDisposed = true;                     }                     try                     {                         if (messageCompleted != null)                             messageCompleted(currentMessageInformation, exception);                     }                     catch (Exception e)                     {                         Trace.TraceError("An error occured when raising the MessageCompleted event, the error will NOT affect the message processing"+ e);                     }                     return;                 }                 catch (Exception e)                 {                     Trace.TraceWarning("Failed to complete transaction, moving to error mode"+ e);                     exception = e;                 }             }             try             {                 if (txDisposed == false && tx != null)                 {                     Trace.TraceWarning("Disposing transaction in error mode");                     tx.Dispose();                 }             }             catch (Exception e)             {                 Trace.TraceWarning("Failed to dispose of transaction in error mode."+ e);             }             if (message == null)                 return;                 try             {                 if (messageCompleted != null)                     messageCompleted(currentMessageInformation, exception);             }             catch (Exception e)             {                 Trace.TraceError("An error occured when raising the MessageCompleted event, the error will NOT affect the message processing"+ e);             }               try             {                 var copy = MessageProcessingFailure;                 if (copy != null)                     copy(currentMessageInformation, exception);             }             catch (Exception moduleException)             {                 Trace.TraceError("Module failed to process message failure: " + exception.Message+                                              moduleException);             }               if (messageQueue.IsTransactional == false)// put the item back in the queue             {                 messageQueue.Send(message);             }         }     You can see quite some processing and handling going on there. Yes this looks like real world code one did put together to make things work and he does not trust his callbacks. I guess these are event handlers which are optional and the delegates were extracted from an event to call them back later when necessary.  Lets see what the author of this code did intend:          private void HandleMessageCompletion(             TransactionHandler transactionHandler,             MessageCompletionHandler handler,             CurrentMessageInformation messageInfo,             ErrorCollector errors             )         {               // commit current pending transaction             transactionHandler.CallHandlerAndCommit(messageInfo, errors);               // We have an error for a null message do not send completion event             if (messageInfo.CurrentMessage == null)                 return;               // Send completion event in any case regardless of errors             handler.OnMessageCompleted(messageInfo, errors);               // put message back if queue is not transactional             transactionHandler.ResendMessageOnError(messageInfo.CurrentMessage, errors);         }   I did not bother to write the intention here again since the code should be pretty self explaining by now. I have used comments to explain the still nontrivial procedure step by step revealing the real intention about all this complex program flow. The original complexity of the problem domain does not go away but by applying the techniques of SRP (Single Responsibility Principle) and some functional style but we can abstract the necessary complexity away in useful abstractions which make it much easier to reason about it. Since most of the method seems to deal with errors I thought it was a good idea to encapsulate the error state of our current message in an ErrorCollector object which stores all exceptions in a list along with a description what the error all was about in the exception itself. We can log it later or not depending on the log level or whatever. It is really just a simple list that encapsulates the current error state.          class ErrorCollector          {              List<Exception> _Errors = new List<Exception>();                public void Add(Exception ex, string description)              {                  ex.Data["Description"] = description;                  _Errors.Add(ex);              }                public Exception Last              {                  get                  {                      return _Errors.LastOrDefault();                  }              }                public bool HasError              {                  get                  {                      return _Errors.Count > 0;                  }              }          }   Since the error state is global we have two choices to store a reference in the other helper objects (TransactionHandler and MessageCompletionHandler)or pass it to the method calls when necessary. I did chose the latter one because a second argument does not hurt and makes it easier to reason about the overall state while the helper objects remain stateless and immutable which makes the helper objects much easier to understand and as a bonus thread safe as well. This does not mean that the stored member variables are stateless or thread safe as well but at least our helper classes are it. Most of the complexity is located the transaction handling I consider as a separate responsibility that I delegate to the TransactionHandler which does nothing if there is no transaction or Call the Before Commit Handler Commit Transaction Dispose Transaction if commit did throw In fact it has a second responsibility to resend the message if the transaction did fail. I did see a good fit there since it deals with transaction failures.          class TransactionHandler          {              TransactionScope _Tx;              Action<CurrentMessageInformation> _BeforeCommit;              OpenedQueue _MessageQueue;                public TransactionHandler(TransactionScope tx, Action<CurrentMessageInformation> beforeCommit, OpenedQueue messageQueue)              {                  _Tx = tx;                  _BeforeCommit = beforeCommit;                  _MessageQueue = messageQueue;              }                public void CallHandlerAndCommit(CurrentMessageInformation currentMessageInfo, ErrorCollector errors)              {                  if (_Tx != null && !errors.HasError)                  {                      try                      {                          if (_BeforeCommit != null)                          {                              _BeforeCommit(currentMessageInfo);                          }                            _Tx.Complete();                          _Tx.Dispose();                      }                      catch (Exception ex)                      {                          errors.Add(ex, "Failed to complete transaction, moving to error mode");                          Trace.TraceWarning("Disposing transaction in error mode");                          try                          {                              _Tx.Dispose();                          }                          catch (Exception ex2)                          {                              errors.Add(ex2, "Failed to dispose of transaction in error mode.");                          }                      }                  }              }                public void ResendMessageOnError(Message message, ErrorCollector errors)              {                  if (errors.HasError && !_MessageQueue.IsTransactional)                  {                      _MessageQueue.Send(message);                  }              }          } If we need to change the handling in the future we have a much easier time to reason about our application flow than before. After we did complete our transaction and called our callback we can call the completion handler which is the main purpose of the HandleMessageCompletion method after all. The responsiblity o the MessageCompletionHandler is to call the completion callback and the failure callback when some error has occurred.            class MessageCompletionHandler          {              Action<CurrentMessageInformation, Exception> _MessageCompletedHandler;              Action<CurrentMessageInformation, Exception> _MessageProcessingFailure;                public MessageCompletionHandler(Action<CurrentMessageInformation, Exception> messageCompletedHandler,                                              Action<CurrentMessageInformation, Exception> messageProcessingFailure)              {                  _MessageCompletedHandler = messageCompletedHandler;                  _MessageProcessingFailure = messageProcessingFailure;              }                  public void OnMessageCompleted(CurrentMessageInformation currentMessageInfo, ErrorCollector errors)              {                  try                  {                      if (_MessageCompletedHandler != null)                      {                          _MessageCompletedHandler(currentMessageInfo, errors.Last);                      }                  }                  catch (Exception ex)                  {                      errors.Add(ex, "An error occured when raising the MessageCompleted event, the error will NOT affect the message processing");                  }                    if (errors.HasError)                  {                      SignalFailedMessage(currentMessageInfo, errors);                  }              }                void SignalFailedMessage(CurrentMessageInformation currentMessageInfo, ErrorCollector errors)              {                  try                  {                      if (_MessageProcessingFailure != null)                          _MessageProcessingFailure(currentMessageInfo, errors.Last);                  }                  catch (Exception moduleException)                  {                      errors.Add(moduleException, "Module failed to process message failure");                  }              }            }   If for some reason I did screw up the logic and we need to call the completion handler from our Transaction handler we can simple add to the CallHandlerAndCommit method a third argument to the MessageCompletionHandler and we are fine again. If the logic becomes even more complex and we need to ensure that the completed event is triggered only once we have now one place the completion handler to capture the state. During this refactoring I simple put things together that belong together and came up with useful abstractions. If you look at the original argument list of the HandleMessageCompletion method I have put many things together:   Original Arguments New Arguments Encapsulate Message message CurrentMessageInformation messageInfo         Message message TransactionScope tx Action<CurrentMessageInformation> beforeTransactionCommit OpenedQueue messageQueue TransactionHandler transactionHandler        TransactionScope tx        OpenedQueue messageQueue        Action<CurrentMessageInformation> beforeTransactionCommit Exception exception,             ErrorCollector errors Action<CurrentMessageInformation, Exception> messageCompleted MessageCompletionHandler handler          Action<CurrentMessageInformation, Exception> messageCompleted          Action<CurrentMessageInformation, Exception> messageProcessingFailure The reason is simple: Put the things that have relationships together and you will find nearly automatically useful abstractions. I hope this makes sense to you. If you see a way to make it even more simple you can show Ayende your improved version as well.

  Read the article

• C#/.NET &ndash; Finding an Item&rsquo;s Index in IEnumerable&lt;T&gt;

  - by James Michael Hare

  Sorry for the long blogging hiatus.  First it was, of course, the holidays hustle and bustle, then my brother and his wife gave birth to their son, so I’ve been away from my blogging for two weeks. Background: Finding an item’s index in List<T> is easy… Many times in our day to day programming activities, we want to find the index of an item in a collection.  Now, if we have a List<T> and we’re looking for the item itself this is trivial: 1: // assume have a list of ints: 2: var list = new List<int> { 1, 13, 42, 64, 121, 77, 5, 99, 132 }; 3:  4: // can find the exact item using IndexOf() 5: var pos = list.IndexOf(64); This will return the position of the item if it’s found, or –1 if not.  It’s easy to see how this works for primitive types where equality is well defined.  For complex types, however, it will attempt to compare them using EqualityComparer<T>.Default which, in a nutshell, relies on the object’s Equals() method. So what if we want to search for a condition instead of equality?  That’s also easy in a List<T> with the FindIndex() method: 1: // assume have a list of ints: 2: var list = new List<int> { 1, 13, 42, 64, 121, 77, 5, 99, 132 }; 3:  4: // finds index of first even number or -1 if not found. 5: var pos = list.FindIndex(i => i % 2 == 0);   Problem: Finding an item’s index in IEnumerable<T> is not so easy... This is all well and good for lists, but what if we want to do the same thing for IEnumerable<T>?  A collection of IEnumerable<T> has no indexing, so there’s no direct method to find an item’s index.  LINQ, as powerful as it is, gives us many tools to get us this information, but not in one step.  As with almost any problem involving collections, there are several ways to accomplish the same goal.  And once again as with almost any problem involving collections, the choice of the solution somewhat depends on the situation. So let’s look at a few possible alternatives.  I’m going to express each of these as extension methods for simplicity and consistency. Solution: The TakeWhile() and Count() combo One of the things you can do is to perform a TakeWhile() on the list as long as your find condition is not true, and then do a Count() of the items it took.  The only downside to this method is that if the item is not in the list, the index will be the full Count() of items, and not –1.  So if you don’t know the size of the list beforehand, this can be confusing. 1: // a collection of extra extension methods off IEnumerable<T> 2: public static class EnumerableExtensions 3: { 4: // Finds an item in the collection, similar to List<T>.FindIndex() 5: public static int FindIndex<T>(this IEnumerable<T> list, Predicate<T> finder) 6: { 7: // note if item not found, result is length and not -1! 8: return list.TakeWhile(i => !finder(i)).Count(); 9: } 10: } Personally, I don’t like switching the paradigm of not found away from –1, so this is one of my least favorites.  Solution: Select with index Many people don’t realize that there is an alternative form of the LINQ Select() method that will provide you an index of the item being selected: 1: list.Select( (item,index) => do something here with the item and/or index... ) This can come in handy, but must be treated with care.  This is because the index provided is only as pertains to the result of previous operations (if any).  For example: 1: // assume have a list of ints: 2: var list = new List<int> { 1, 13, 42, 64, 121, 77, 5, 99, 132 }; 3:  4: // you'd hope this would give you the indexes of the even numbers 5: // which would be 2, 3, 8, but in reality it gives you 0, 1, 2 6: list.Where(item => item % 2 == 0).Select((item,index) => index); The reason the example gives you the collection { 0, 1, 2 } is because the where clause passes over any items that are odd, and therefore only the even items are given to the select and only they are given indexes. Conversely, we can’t select the index and then test the item in a Where() clause, because then the Where() clause would be operating on the index and not the item! So, what we have to do is to select the item and index and put them together in an anonymous type.  It looks ugly, but it works: 1: // extensions defined on IEnumerable<T> 2: public static class EnumerableExtensions 3: { 4: // finds an item in a collection, similar to List<T>.FindIndex() 5: public static int FindIndex<T>(this IEnumerable<T> list, Predicate<T> finder) 6: { 7: // if you don't name the anonymous properties they are the variable names 8: return list.Select((item, index) => new { item, index }) 9: .Where(p => finder(p.item)) 10: .Select(p => p.index + 1) 11: .FirstOrDefault() - 1; 12: } 13: }     So let’s look at this, because i know it’s convoluted: First Select() joins the items and their indexes into an anonymous type. Where() filters that list to only the ones matching the predicate. Second Select() picks the index of the matches and adds 1 – this is to distinguish between not found and first item. FirstOrDefault() returns the first item found from the previous clauses or default (zero) if not found. Subtract one so that not found (zero) will be –1, and first item (one) will be zero. The bad thing is, this is ugly as hell and creates anonymous objects for each item tested until it finds the match.  This concerns me a bit but we’ll defer judgment until compare the relative performances below. Solution: Convert ToList() and use FindIndex() This solution is easy enough.  We know any IEnumerable<T> can be converted to List<T> using the LINQ extension method ToList(), so we can easily convert the collection to a list and then just use the FindIndex() method baked into List<T>. 1: // a collection of extension methods for IEnumerable<T> 2: public static class EnumerableExtensions 3: { 4: // find the index of an item in the collection similar to List<T>.FindIndex() 5: public static int FindIndex<T>(this IEnumerable<T> list, Predicate<T> finder) 6: { 7: return list.ToList().FindIndex(finder); 8: } 9: } This solution is simplicity itself!  It is very concise and elegant and you need not worry about anyone misinterpreting what it’s trying to do (as opposed to the more convoluted LINQ methods above). But the main thing I’m concerned about here is the performance hit to allocate the List<T> in the ToList() call, but once again we’ll explore that in a second. Solution: Roll your own FindIndex() for IEnumerable<T> Of course, you can always roll your own FindIndex() method for IEnumerable<T>.  It would be a very simple for loop which scans for the item and counts as it goes.  There’s many ways to do this, but one such way might look like: 1: // extension methods for IEnumerable<T> 2: public static class EnumerableExtensions 3: { 4: // Finds an item matching a predicate in the enumeration, much like List<T>.FindIndex() 5: public static int FindIndex<T>(this IEnumerable<T> list, Predicate<T> finder) 6: { 7: int index = 0; 8: foreach (var item in list) 9: { 10: if (finder(item)) 11: { 12: return index; 13: } 14:  15: index++; 16: } 17:  18: return -1; 19: } 20: } Well, it’s not quite simplicity, and those less familiar with LINQ may prefer it since it doesn’t include all of the lambdas and behind the scenes iterators that come with deferred execution.  But does having this long, blown out method really gain us much in performance? Comparison of Proposed Solutions So we’ve now seen four solutions, let’s analyze their collective performance.  I took each of the four methods described above and run them over 100,000 iterations of lists of size 10, 100, 1000, and 10000 and here’s the performance results.  Then I looked for targets at the begining of the list (best case), middle of the list (the average case) and not in the list (worst case as must scan all of the list). Each of the times below is the average time in milliseconds for one execution as computer over the 100,000 iterations: Searches Matching First Item (Best Case)   10 100 1000 10000 TakeWhile 0.0003 0.0003 0.0003 0.0003 Select 0.0005 0.0005 0.0005 0.0005 ToList 0.0002 0.0003 0.0013 0.0121 Manual 0.0001 0.0001 0.0001 0.0001   Searches Matching Middle Item (Average Case)   10 100 1000 10000 TakeWhile 0.0004 0.0020 0.0191 0.1889 Select 0.0008 0.0042 0.0387 0.3802 ToList 0.0002 0.0007 0.0057 0.0562 Manual 0.0002 0.0013 0.0129 0.1255   Searches Where Not Found (Worst Case)   10 100 1000 10000 TakeWhile 0.0006 0.0039 0.0381 0.3770 Select 0.0012 0.0081 0.0758 0.7583 ToList 0.0002 0.0012 0.0100 0.0996 Manual 0.0003 0.0026 0.0253 0.2514   Notice something interesting here, you’d think the “roll your own” loop would be the most efficient, but it only wins when the item is first (or very close to it) regardless of list size.  In almost all other cases though and in particular the average case and worst case, the ToList()/FindIndex() combo wins for performance, even though it is creating some temporary memory to hold the List<T>.  If you examine the algorithm, the reason why is most likely because once it’s in a ToList() form, internally FindIndex() scans the internal array which is much more efficient to iterate over.  Thus, it takes a one time performance hit (not including any GC impact) to create the List<T> but after that the performance is much better. Summary If you’re concerned about too many throw-away objects, you can always roll your own FindIndex() method, but for sheer simplicity and overall performance, using the ToList()/FindIndex() combo performs best on nearly all list sizes in the average and worst cases.    Technorati Tags: C#,.NET,Litte Wonders,BlackRabbitCoder,Software,LINQ,List

  Read the article

• Ajax-based data loading using jQuery.load() function in ASP.NET

  - by hajan

  In general, jQuery has made Ajax very easy by providing low-level interface, shorthand methods and helper functions, which all gives us great features of handling Ajax requests in our ASP.NET Webs. The simplest way to load data from the server and place the returned HTML in browser is to use the jQuery.load() function. The very firs time when I started playing with this function, I didn't believe it will work that much easy. What you can do with this method is simply call given url as parameter to the load function and display the content in the selector after which this function is chained. So, to clear up this, let me give you one very simple example: $("#result").load("AjaxPages/Page.html"); As you can see from the above image, after clicking the ‘Load Content’ button which fires the above code, we are making Ajax Get and the Response is the entire page HTML. So, rather than using (old) iframes, you can now use this method to load other html pages inside the page from where the script with load function is called. This method is equivalent to the jQuery Ajax Get method $.get(url, data, function () { }) only that the $.load() is method rather than global function and has an implicit callback function. To provide callback to your load, you can simply add function as second parameter, see example: $("#result").load("AjaxPages/Page.html", function () { alert("Page.html has been loaded successfully!") }); Since load is part of the chain which is follower of the given jQuery Selector where the content should be loaded, it means that the $.load() function won't execute if there is no such selector found within the DOM. Another interesting thing to mention, and maybe you've asked yourself is how we know if GET or POST method type is executed? It's simple, if we provide 'data' as second parameter to the load function, then POST is used, otherwise GET is assumed. POST $("#result").load("AjaxPages/Page.html", { "name": "hajan" }, function () { ////callback function implementation });   GET $("#result").load("AjaxPages/Page.html", function () { ////callback function implementation });   Another important feature that $.load() has ($.get() does not) is loading page fragments. Using jQuery's selector capability, you can do this: $("#result").load("AjaxPages/Page.html #resultTable"); In our Page.html, the content now is: So, after the call, only the table with id resultTable will load in our page.   As you can see, we have loaded only the table with id resultTable (1) inside div with id result (2). This is great feature since we won't need to filter the returned HTML content again in our callback function on the master page from where we have called $.load() function. Besides the fact that you can simply call static HTML pages, you can also use this function to load dynamic ASPX pages or ASP.NET ASHX Handlers . Lets say we have another page (ASPX) in our AjaxPages folder with name GetProducts.aspx. This page has repeater control (or anything you want to bind dynamic server-side content) that displays set of data in it. Now, I want to filter the data in the repeater based on the Query String parameter provided when calling that page. For example, if I call the page using GetProducts.aspx?category=computers, it will load only computers… so, this will filter the products automatically by given category. The example ASPX code of GetProducts.aspx page is: <%@ Page Language="C#" AutoEventWireup="true" CodeBehind="GetProducts.aspx.cs" Inherits="WebApplication1.AjaxPages.GetProducts" %> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head runat="server"> <title></title> </head> <body> <form id="form1" runat="server"> <div> <table id="tableProducts"> <asp:Repeater ID="rptProducts" runat="server"> <HeaderTemplate> <tr> <th>Product</th> <th>Price</th> <th>Category</th> </tr> </HeaderTemplate> <ItemTemplate> <tr> <td> <%# Eval("ProductName")%> </td> <td> <%# Eval("Price") %> </td> <td> <%# Eval("Category") %> </td> </tr> </ItemTemplate> </asp:Repeater> </ul> </div> </form> </body> </html> The C# code-behind sample code is: public partial class GetProducts : System.Web.UI.Page { public List<Product> products; protected override void OnInit(EventArgs e) { LoadSampleProductsData(); //load sample data base.OnInit(e); } protected void Page_Load(object sender, EventArgs e) { if (Request.QueryString.Count > 0) { if (!string.IsNullOrEmpty(Request.QueryString["category"])) { string category = Request.QueryString["category"]; //get query string into string variable //filter products sample data by category using LINQ //and add the collection as data source to the repeater rptProducts.DataSource = products.Where(x => x.Category == category); rptProducts.DataBind(); //bind repeater } } } //load sample data method public void LoadSampleProductsData() { products = new List<Product>(); products.Add(new Product() { Category = "computers", Price = 200, ProductName = "Dell PC" }); products.Add(new Product() { Category = "shoes", Price = 90, ProductName = "Nike" }); products.Add(new Product() { Category = "shoes", Price = 66, ProductName = "Adidas" }); products.Add(new Product() { Category = "computers", Price = 210, ProductName = "HP PC" }); products.Add(new Product() { Category = "shoes", Price = 85, ProductName = "Puma" }); } } //sample Product class public class Product { public string ProductName { get; set; } public decimal Price { get; set; } public string Category { get; set; } } Mainly, I just have sample data loading function, Product class and depending of the query string, I am filtering the products list using LINQ Where statement. If we run this page without query string, it will show no data. If we call the page with category query string, it will filter automatically. Example: /AjaxPages/GetProducts.aspx?category=shoes The result will be: or if we use category=computers, like this /AjaxPages/GetProducts.aspx?category=computers, the result will be: So, now using jQuery.load() function, we can call this page with provided query string parameter and load appropriate content… The ASPX code in our Default.aspx page, which will call the AjaxPages/GetProducts.aspx page using jQuery.load() function is: <asp:RadioButtonList ID="rblProductCategory" runat="server"> <asp:ListItem Text="Shoes" Value="shoes" Selected="True" /> <asp:ListItem Text="Computers" Value="computers" /> </asp:RadioButtonList> <asp:Button ID="btnLoadProducts" runat="server" Text="Load Products" /> <!-- Here we will load the products, based on the radio button selection--> <div id="products"></div> </form> The jQuery code: $("#<%= btnLoadProducts.ClientID %>").click(function (event) { event.preventDefault(); //preventing button's default behavior var selectedRadioButton = $("#<%= rblProductCategory.ClientID %> input:checked").val(); //call GetProducts.aspx with the category query string for the selected category in radio button list //filter and get only the #tableProducts content inside #products div $("#products").load("AjaxPages/GetProducts.aspx?category=" + selectedRadioButton + " #tableProducts"); }); The end result: You can download the code sample from here. You can read more about jQuery.load() function here. I hope this was useful blog post for you. Please do let me know your feedback. Best Regards, Hajan

  Read the article

• Bug with Set / Get Accessor in .Net 3.5

  - by MarkPearl

  I spent a few hours scratching my head on this one... So I thought I would blog about it in case someone else had the same headache. Assume you have a class, and you are wanting to use the INotifyPropertyChanged interface so that when you bind to an instance of the class, you get the magic sauce of binding to do you updates to the UI. Well, I had a special instance where I wanted one of the properties of the class to add some additional formatting to itself whenever someone changed its value (see the code below).   class Test: INotifyPropertyChanged {     private string_inputValue;     public stringInputValue     {         get        {             return_inputValue;         }         set        {             if(value!= _inputValue)             {                 _inputValue = value+ "Extra Stuff";                 NotifyPropertyChanged("InputValue");                     }         }     }     public eventPropertyChangedEventHandler PropertyChanged;     public voidNotifyPropertyChanged(stringinfo)     {         if(PropertyChanged != null)         {             PropertyChanged(this, newPropertyChangedEventArgs(info));         }     } }   Everything looked fine, but when I ran it in my WPF project, the textbox I was binding to would not update? I couldn’t understand it! I thought the code made sense, so why wasn’t it working? Eventually StackOverflow came to the rescue, where I was told that it was a bug in the .Net 3.5 Runtime and that a fix was scheduled in .Net 4 For those who have the same problem, here is the workaround… You need to put the NotifyPropertyChanged method on the application thread! public string InputValue { get { return _inputValue; } set { if (value != _inputValue) { _inputValue = value + "Extra Stuff"; // // React to the type of measurement // Application.Current.Dispatcher.BeginInvoke((Action)delegate { NotifyPropertyChanged("InputValue"); }); } } }

  Read the article

• SOLID Thoughts

  - by GeekAgilistMercenary

  SOLID came up again in discussion.  What is SOLID?  Well, glad you asked, because I am going to elaborate on the SOLID Principles a bit. Initial Concept S Single Responsibility Principle O Open/Closed Principle L Liskov Substitution Principle I Interface Segregation Principle D Dependency Inversion/Injection Principle The Single Responsibility Principle (SRP) is stated that every object should have a single responsibility and should be entirely encapsulated by the class.  This helps keep cohesion.  Here is a short example, starting with a basic class. public class Car { decimal Gas; int Doors; int Speed; decimal RampJumpSpeed; } Now I will refactor a little bit to make it a bit more SRP friendly. public class Car { decimal Gas; int Speed; }   public class DuneBuggy : Car { decimal RampJumpSpeed; }   public class EconomyCar : Car { int Doors; } What we end up with, instead of one class, is an abstract class and two classes that have their respective methods or properties to keep the responsibilities were they need to be. The Open Closed Principle (OCP) is one of my favorites, which states simply, that you should be able to extend a classes behavior without modifying it.  There are a couple of ways one can extend a class, by inheritance, composition, or by proxy implementation.  The Liskov Substitution Principle (LSP) states that a derived class must be substitutable for their base classes. The Dependency Inversion Principle (DIP) states that one should depend on abstractions and not on concrete implementations. Finally, the Interface Segregation Principle (ISP) states that fine grain interfaces should be client specific. So hope that helps with kicking off a basic understanding of SOLID Principles.  I will be following this entry up with some new bits in the near future related to good software design and practice. Original post.

  Read the article

• Organizing Business and Presentation entities

  - by simoneL

  Background I am developing a WPF project. This is the basic structure: User Interface (WPF Project); Interfaces (class library, contains all the interfaces and the entities used by the application; Modules (every module contains the logic of a specific argument, e.g. File Management, and can eventually contains Wpf User Controls). In the WPF Controls, to facilitate the binding operations I have created a BaseViewModel class which contains a Raise method that automates the binding mechanism (for further details, I used a technique similar to that one described in this article). The problem Understand which is the best way to separate Presentation form from the Business form in the entities classes. The case In the Interfaces project I have, for instance, the class User public class User { public virtual string Name { get; set; } // Other properties } In one of the modules I need to use the User class and to bind its properties to the User Interface controls. To do so I have to use a custom implementation of the get and set keywords. At first point, I thought to create a class in the Module called, for instance, ClientUser and override the properties that I need: public class ClientUser : User { private string name; public override string Name { get { return name; } set { Raise(out name, value); } } // Other properties } The problem is the Raise method, which is declared in the BaseViewModel class, but due to C# single inheritance constraint, I can't inherit from both classes. Which is the right way to implement this architecture?

  Read the article

• Camera wont stay behind model after pitch, then rotation

  - by ChocoMan

  I have a camera position behind a model. Currently, if I push the left thumbstick making my model move forward, backward, or strafe, the camera stays with the model. If I push the right thumbstick left or right, the model rotates in those directions fine along with the camera rotating while maintaining its position relatively behind the model. But when I pitch the model up or down, then rotate the model afterwards, the camera moves slightly rotates in a clock-like fashion behind the model. If I do a few rotations of the model and try to pitch the camera, the camera will eventually be looking at the side, then eventually the front of the model while also rotating in a clock-like fashion. My question is, how do I keep the camera to pitch up and down behind the model no matter how much the model has rotated? Here is what I got: // Rotates model and pitches camera on its own axis public void modelRotMovement(GamePadState pController) { // Rotates Camera with model Yaw = pController.ThumbSticks.Right.X * MathHelper.ToRadians(angularSpeed); // Pitches Camera around model Pitch = pController.ThumbSticks.Right.Y * MathHelper.ToRadians(angularSpeed); AddRotation = Quaternion.CreateFromYawPitchRoll(Yaw, 0, 0); ModelLoad.MRotation *= AddRotation; MOrientation = Matrix.CreateFromQuaternion(ModelLoad.MRotation); } // Orbit (yaw) Camera around with model (only seeing back of model) public void cameraYaw(Vector3 axisYaw, float yaw) { ModelLoad.CameraPos = Vector3.Transform(ModelLoad.CameraPos - ModelLoad.camTarget, Matrix.CreateFromAxisAngle(axisYaw, yaw)) + ModelLoad.camTarget; } // Raise camera above or below model's shoulders public void cameraPitch(Vector3 axisPitch, float pitch) { ModelLoad.CameraPos = Vector3.Transform(ModelLoad.CameraPos - ModelLoad.camTarget, Matrix.CreateFromAxisAngle(axisPitch, pitch)) + ModelLoad.camTarget; } // Call in update method public void updateCamera() { cameraYaw(Vector3.Up, Yaw); cameraPitch(Vector3.Right, Pitch); } NOTE: I tried to use addPitch just like addRotation but it didn't work...

  Read the article

• Where'd My Data Go? (and/or...How Do I Get Rid of It?)

  - by David Paquette

  Want to get a better idea of how cascade deletes work in Entity Framework Code First scenarios? Want to see it in action? Stick with us as we quickly demystify what happens when you tell your data context to nuke a parent entity. This post is authored by Calgary .NET User Group Leader David Paquette with help from Microsoft MVP in Asp.Net James Chambers. We got to spend a great week back in March at Prairie Dev Con West, chalk full of sessions, presentations, workshops, conversations and, of course, questions.  One of the questions that came up during my session: "How does Entity Framework Code First deal with cascading deletes?". James and I had different thoughts on what the default was, if it was different from SQL server, if it was the same as EF proper and if there was a way to override whatever the default was.  So we built a set of examples and figured out that the answer is simple: it depends.  (Download Samples) Consider the example of a hockey league. You have several different entities in the league including games, teams that play the games and players that make up the teams. Each team also has a mascot.  If you delete a team, we need a couple of things to happen: The team, games and mascot will be deleted, and The players for that team will remain in the league (and therefore the database) but they should no longer be assigned to a team. So, let's make this start to come together with a look at the default behaviour in SQL when using an EDMX-driven project. The Reference – Understanding EF's Behaviour with an EDMX/DB First Approach First up let’s take a look at the DB first approach.  In the database, we defined 4 tables: Teams, Players, Mascots, and Games.  We also defined 4 foreign keys as follows: Players.Team_Id (NULL) –> Teams.Id Mascots.Id (NOT NULL) –> Teams.Id (ON DELETE CASCADE) Games.HomeTeam_Id (NOT NULL) –> Teams.Id Games.AwayTeam_Id (NOT NULL) –> Teams.Id Note that by specifying ON DELETE CASCADE for the Mascots –> Teams foreign key, the database will automatically delete the team’s mascot when the team is deleted.  While we want the same behaviour for the Games –> Teams foreign keys, it is not possible to accomplish this using ON DELETE CASCADE in SQL Server.  Specifying a ON DELETE CASCADE on these foreign keys would cause a circular reference error: The series of cascading referential actions triggered by a single DELETE or UPDATE must form a tree that contains no circular references. No table can appear more than one time in the list of all cascading referential actions that result from the DELETE or UPDATE – MSDN When we create an entity data model from the above database, we get the following:   In order to get the Games to be deleted when the Team is deleted, we need to specify End1 OnDelete action of Cascade for the HomeGames and AwayGames associations.   Now, we have an Entity Data Model that accomplishes what we set out to do.  One caveat here is that Entity Framework will only properly handle the cascading delete when the the players and games for the team have been loaded into memory.  For a more detailed look at Cascade Delete in EF Database First, take a look at this blog post by Alex James.   Building The Same Sample with EF Code First Next, we're going to build up the model with the code first approach.  EF Code First is defined on the Ado.Net team blog as such: Code First allows you to define your model using C# or VB.Net classes, optionally additional configuration can be performed using attributes on your classes and properties or by using a Fluent API. Your model can be used to generate a database schema or to map to an existing database. Entity Framework Code First follows some conventions to determine when to cascade delete on a relationship.  More details can be found on MSDN: If a foreign key on the dependent entity is not nullable, then Code First sets cascade delete on the relationship. If a foreign key on the dependent entity is nullable, Code First does not set cascade delete on the relationship, and when the principal is deleted the foreign key will be set to null. The multiplicity and cascade delete behavior detected by convention can be overridden by using the fluent API. For more information, see Configuring Relationships with Fluent API (Code First). Our DbContext consists of 4 DbSets: public DbSet<Team> Teams { get; set; } public DbSet<Player> Players { get; set; } public DbSet<Mascot> Mascots { get; set; } public DbSet<Game> Games { get; set; } When we set the Mascot –> Team relationship to required, Entity Framework will automatically delete the Mascot when the Team is deleted.  This can be done either using the [Required] data annotation attribute, or by overriding the OnModelCreating method of your DbContext and using the fluent API. Data Annotations: public class Mascot { public int Id { get; set; } public string Name { get; set; } [Required] public virtual Team Team { get; set; } } Fluent API: protected override void OnModelCreating(DbModelBuilder modelBuilder) { modelBuilder.Entity<Mascot>().HasRequired(m => m.Team); } The Player –> Team relationship is automatically handled by the Code First conventions. When a Team is deleted, the Team property for all the players on that team will be set to null.  No additional configuration is required, however all the Player entities must be loaded into memory for the cascading to work properly. The Game –> Team relationship causes some grief in our Code First example.  If we try setting the HomeTeam and AwayTeam relationships to required, Entity Framework will attempt to set On Cascade Delete for the HomeTeam and AwayTeam foreign keys when creating the database tables.  As we saw in the database first example, this causes a circular reference error and throws the following SqlException: Introducing FOREIGN KEY constraint 'FK_Games_Teams_AwayTeam_Id' on table 'Games' may cause cycles or multiple cascade paths. Specify ON DELETE NO ACTION or ON UPDATE NO ACTION, or modify other FOREIGN KEY constraints. Could not create constraint. To solve this problem, we need to disable the default cascade delete behaviour using the fluent API: protected override void OnModelCreating(DbModelBuilder modelBuilder) { modelBuilder.Entity<Mascot>().HasRequired(m => m.Team); modelBuilder.Entity<Team>() .HasMany(t => t.HomeGames) .WithRequired(g => g.HomeTeam) .WillCascadeOnDelete(false); modelBuilder.Entity<Team>() .HasMany(t => t.AwayGames) .WithRequired(g => g.AwayTeam) .WillCascadeOnDelete(false); base.OnModelCreating(modelBuilder); } Unfortunately, this means we need to manually manage the cascade delete behaviour.  When a Team is deleted, we need to manually delete all the home and away Games for that Team. foreach (Game awayGame in jets.AwayGames.ToArray()) { entities.Games.Remove(awayGame); } foreach (Game homeGame in homeGames) { entities.Games.Remove(homeGame); } entities.Teams.Remove(jets); entities.SaveChanges();   Overriding the Defaults – When and How To As you have seen, the default behaviour of Entity Framework Code First can be overridden using the fluent API.  This can be done by overriding the OnModelCreating method of your DbContext, or by creating separate model override files for each entity.  More information is available on MSDN.   Going Further These were simple examples but they helped us illustrate a couple of points. First of all, we were able to demonstrate the default behaviour of Entity Framework when dealing with cascading deletes, specifically how entity relationships affect the outcome. Secondly, we showed you how to modify the code and control the behaviour to get the outcome you're looking for. Finally, we showed you how easy it is to explore this kind of thing, and we're hoping that you get a chance to experiment even further. For example, did you know that: Entity Framework Code First also works seamlessly with SQL Azure (MSDN) Database creation defaults can be overridden using a variety of IDatabaseInitializers  (Understanding Database Initializers) You can use Code Based migrations to manage database upgrades as your model continues to evolve (MSDN) Next Steps There's no time like the present to start the learning, so here's what you need to do: Get up-to-date in Visual Studio 2010 (VS2010 | SP1) or Visual Studio 2012 (VS2012) Build yourself a project to try these concepts out (or download the sample project) Get into the community and ask questions! There are a ton of great resources out there and community members willing to help you out (like these two guys!). Good luck! About the Authors David Paquette works as a lead developer at P2 Energy Solutions in Calgary, Alberta where he builds commercial software products for the energy industry.  Outside of work, David enjoys outdoor camping, fishing, and skiing. David is also active in the software community giving presentations both locally and at conferences. David also serves as the President of Calgary .Net User Group. James Chambers crafts software awesomeness with an incredible team at LogiSense Corp, based in Cambridge, Ontario. A husband, father and humanitarian, he is currently residing in the province of Manitoba where he resists the urge to cheer for the Jets and maintains he allegiance to the Calgary Flames. When he's not active with the family, outdoors or volunteering, you can find James speaking at conferences and user groups across the country about web development and related technologies.

  Read the article

• WebSocket Samples in GlassFish 4 build 66 - javax.websocket.* package: TOTD #190

  - by arungupta

  This blog has published a few blogs on using JSR 356 Reference Implementation (Tyrus) integrated in GlassFish 4 promoted builds. TOTD #183: Getting Started with WebSocket in GlassFish TOTD #184: Logging WebSocket Frames using Chrome Developer Tools, Net-internals and Wireshark TOTD #185: Processing Text and Binary (Blob, ArrayBuffer, ArrayBufferView) Payload in WebSocket TOTD #186: Custom Text and Binary Payloads using WebSocket TOTD #189: Collaborative Whiteboard using WebSocket in GlassFish 4 The earlier blogs created a WebSocket endpoint as: import javax.net.websocket.annotations.WebSocketEndpoint;@WebSocketEndpoint("websocket")public class MyEndpoint { . . . Based upon the discussion in JSR 356 EG, the package names have changed to javax.websocket.*. So the updated endpoint definition will look like: import javax.websocket.WebSocketEndpoint;@WebSocketEndpoint("websocket")public class MyEndpoint { . . . The POM dependency is: <dependency> <groupId>javax.websocket</groupId> <artifactId>javax.websocket-api</artifactId> <version>1.0-b09</version> </dependency> And if you are using GlassFish 4 build 66, then you also need to provide a dummy EndpointFactory implementation as: import javax.websocket.WebSocketEndpoint;@WebSocketEndpoint(value="websocket", factory=MyEndpoint.DummyEndpointFactory.class)public class MyEndpoint { . . .   class DummyEndpointFactory implements EndpointFactory {    @Override public Object createEndpoint() { return null; }  }} This is only interim and will be cleaned up in subsequent builds. But I've seen couple of complaints about this already and so this deserves a short blog. Have you been tracking the latest Java EE 7 implementations in GlassFish 4 promoted builds ?

  Read the article

• OpenGL camera moves faster than player

  - by opiop65

  I have a side scroller game made in OpenGL, and I'm trying to center the player in the viewport when he moves. I know how to do it: cameraX = Width / 2 / TileSize - playerPosX cameraY = Height / 2 / TileSize - playerPosY However, I have a problem. The player and "camera" move, but the player moves faster than the "camera" scrolls. So, the player can actually move out of the screen. Some code, this is how I translate the camera: public Camera(){ } public void update(Player p){ glTranslatef(-p.getPos().x - Main.WIDTH / 64 / 2, -p.getPos().y - Main.HEIGHT / 64 / 2, 1); } Here's how I move the player: public void update(){ if(Keyboard.isKeyDown(Keyboard.KEY_D)){ this.move(MOVESPEED, 0); } if(Keyboard.isKeyDown(Keyboard.KEY_A)){ this.move(-MOVESPEED, 0); } } The move method: public void move(float x, float y){ this.getPos().set(this.getPos().x + x, this.getPos().y + y); } And then after I move the player, I update the player's geometry, which shouldn't matter. What am I doing wrong here, this seems like such a simple problem, yet it doesn't work!

  Read the article

• how to double buffer in multiple classes with java

  - by kdavis8

  I am creating a Java 2D video game. I can load graphics just fine, but when it gets into double buffering I have issues. My source code package myPackage; import java.awt.Color; import java.awt.Graphics; import java.awt.Graphics2D; import java.awt.Image; import java.awt.Toolkit; import java.awt.image.BufferStrategy; import java.awt.image.BufferedImage; import javax.swing.JFrame; public class GameView extends JFrame { private BufferedImage backbuffer; private Graphics2D g2d; public GameView() { setBounds(0, 0, 500, 500); setVisible(true); setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); backbuffer = new BufferedImage(getHeight(), getWidth(), BufferedImage.TYPE_INT_BGR); g2d = backbuffer.createGraphics(); Toolkit tk = Toolkit.getDefaultToolkit(); Image img = tk.getImage(this.getClass().getResource("cage.png")); g2d.setColor(Color.red); //g2d.drawString("Hello",100,100); g2d.drawImage(img, 100, 100, this); repaint(); } public static void main(String args[]) { new GameView(); } public void paint(Graphics g) { g2d = (Graphics2D)g; g2d.drawImage(backbuffer, 0, 0, this); } }

  Read the article

• 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.

  Read the article

• Clipping polygons in XNA with stencil (not using spritebatch)

  - by Blau

  The problem... i'm drawing polygons, in this case boxes, and i want clip children polygons with its parent's client area. // Class Region public void Render(GraphicsDevice Device, Camera Camera) { int StencilLevel = 0; Device.Clear( ClearOptions.Stencil, Vector4.Zero, 0, StencilLevel ); Render( Device, Camera, StencilLevel ); } private void Render(GraphicsDevice Device, Camera Camera, int StencilLevel) { Device.SamplerStates[0] = this.SamplerState; Device.Textures[0] = this.Texture; Device.RasterizerState = RasterizerState.CullNone; Device.BlendState = BlendState.AlphaBlend; Device.DepthStencilState = DepthStencilState.Default; Effect.Prepare(this, Camera ); Device.DepthStencilState = GlobalContext.GraphicsStates.IncMask; Device.ReferenceStencil = StencilLevel; foreach ( EffectPass pass in Effect.Techniques[Technique].Passes ) { pass.Apply( ); Device.DrawUserIndexedPrimitives<VertexPositionColorTexture>( PrimitiveType.TriangleList, VertexData, 0, VertexData.Length, IndexData, 0, PrimitiveCount ); } foreach ( Region child in ChildrenRegions ) { child.Render( Device, Camera, StencilLevel + 1 ); } Effect.Prepare( this, Camera ); // This does not works Device.BlendState = GlobalContext.GraphicsStates.NoWriteColor; Device.DepthStencilState = GlobalContext.GraphicsStates.DecMask; Device.ReferenceStencil = StencilLevel; // This should be +1, but in that case the last drrawed is blue and overlap all foreach ( EffectPass pass in Effect.Techniques[Technique].Passes ) { pass.Apply( ); Device.DrawUserIndexedPrimitives<VertexPositionColorTexture>( PrimitiveType.TriangleList, VertexData, 0, VertexData.Length, IndexData, 0, PrimitiveCount ); } } public static class GraphicsStates { public static BlendState NoWriteColor = new BlendState( ) { ColorSourceBlend = Blend.One, AlphaSourceBlend = Blend.One, ColorDestinationBlend = Blend.InverseSourceAlpha, AlphaDestinationBlend = Blend.InverseSourceAlpha, ColorWriteChannels1 = ColorWriteChannels.None }; public static DepthStencilState IncMask = new DepthStencilState( ) { StencilEnable = true, StencilFunction = CompareFunction.Equal, StencilPass = StencilOperation.IncrementSaturation, }; public static DepthStencilState DecMask = new DepthStencilState( ) { StencilEnable = true, StencilFunction = CompareFunction.Equal, StencilPass = StencilOperation.DecrementSaturation, }; } How can achieve this? EDIT: I've just relized that the NoWriteColors.ColorWriteChannels1 should be NoWriteColors.ColorWriteChannels. :) Now it's clipping right. Any other approach?

  Read the article

• List querying with Lamda Expressions in C#.NET

  - by Pavan Kumar Pabothu

  public class Employees {     public int EmployeeId { get; set; }     public string Name { get; set; }     public decimal Salary { get; set; } } List<Employees> employeeList = new List<Employees>(); List<Employees> resultList = new List<Employees>(); decimal maxSalary; List<string> employeeNames = new List<string>(); protected void Page_Load(object sender, EventArgs e) {     if (!IsPostBack)     {         FillEmployees();     }     // Getting a max salary     maxSalary = employeeList.Max((emp) => emp.Salary);     // Filtering a List     resultList = employeeList.Where((emp) => emp.Salary > 50000).ToList();     // Sorting a List     // To get a descending order replace OrderBy with OrderByDescending     resultList = employeeList.OrderBy<Employees, decimal>((emp) => emp.Salary).ToList();     // Get the List of employee names only     employeeNames = employeeList.Select<Employees, string>(emp => emp.Name).ToList();        // Getting a customized object with a given list     var employeeResultSet = employeeList.Select((emp) => new { Name = emp.Name, BigSalary = emp.Salary > 50000 }).ToList(); } private void FillEmployees() {     employeeList.Add(new Employees { EmployeeId = 1, Name = "Shankar", Salary = 125000 });     employeeList.Add(new Employees { EmployeeId = 2, Name = "Prasad", Salary = 90000 });     employeeList.Add(new Employees { EmployeeId = 3, Name = "Mahesh", Salary = 36000 }); }

  Read the article

• Java EE 7 JSR update

  - by Heather VanCura

  Java EE 7 JSR update...in case you missed the last few entries with JSR updates, there are 8 Java EE 7 JSRs currently in JCP milestone review stages.  Your input is requested and needed! JSR 342: Early Draft Review 2– Java Platform, Enterprise Edition 7 (Java EE 7) Specification (review ends 30 November); Oracle JSR 107: Early Draft Review - JCACHE - Java Temporary Caching API (review ends 22 November); Greg Luck, Oracle JSR 236: Early Draft Review – Concurrency Utilities for Java EE (review ends 15 December); Oracle JSR 338: Early Draft Review 2 – Java Persistence 2 (review ends 30 November); Oracle JSR 346: Public Review – Contexts and Dependency Injection for Java EE 1.1 (EC ballot 4-17 December); RedHat JSR 352: Public Review – Batch Applications for the Java Platform (EC ballot 4-17 December); IBM JSR 349: Public Review – Bean Validation 1.1 (EC ballot 20- 26 November); RedHat JSR 339: Public Review – JAX-RS 2.0: The Java API for RESTful Web Services (Review period ended, EC ballot ends 26 November); Oracle  Also, check out the Java EE wiki with a specification and schedule update, including most recently, the addition of JSR 236.

  Read the article

• Alternatives to Component Based Architecture?

  - by Ben Lakey

  Usually when I develop a game I will use an architecture like what you see below. What other architectures are popular for simple game development? I'm concerned about having a narrow view of what exists out there for architectures beyond this. Is this an example of component-based architecture? Or is this something else? What would that look like? What alternatives exist? public abstract class ComponentBase { protected final Collection<ComponentBase> subComponents = new LinkedList<ComponentBase>(); private boolean enableInput; private boolean isVisible; protected ComponentBase(boolean enableInput, boolean isVisible) { this.enableInput = enableInput; this.isVisible = isVisible; } public void render(Graphics2D graphics) { for(ComponentBase gameComponent : this.subComponents) { if(gameComponent.isVisible()) { gameComponent.render(graphics); } } } public void input(InputData input) { for(ComponentBase gameComponent : this.subComponents) { if(gameComponent.inputIsEnabled()) { gameComponent.input(input); } } } ... getters/setters ... public void update(long elapsedTimeMillis) { for(ComponentBase gameComponent : this.subComponents) { gameComponent.update(elapsedTimeMillis); } } }

  Read the article

• DI and hypothetical readonly setters in C#

  - by Luis Ferrao

  Sometimes I would like to declare a property like this: public string Name { get; readonly set; } I am wondering if anyone sees a reason why such a syntax shouldn't exist. I believe that because it is a subset of "get; private set;", it could only make code more robust. My feeling is that such setters would be extremely DI friendly, but of course I'm more interested in hearing your opinions than my own, so what do you think? I am aware of 'public readonly' fields, but those are not interface friendly so I don't even consider them. That said, I don't mind if you bring them up into the discussion Edit I realize reading the comments that perhaps my idea is a little confusing. The ultimate purpose of this new syntax would be to have an automatic property syntax that specifies that the backing private field should be readonly. Basically declaring a property using my hypothetical syntax public string Name { get; readonly set; } would be interpreted by C# as: private readonly string name; public string Name { get { return this.name; } } And the reason I say this would be DI friendly is because when we rely heavily on constructor injection, I believe it is good practice to declare our constructor injected fields as readonly.

  Read the article

• Enumerable Interleave Extension Method

  - by João Angelo

  A recent stackoverflow question, which I didn’t bookmark and now I’m unable to find, inspired me to implement an extension method for Enumerable that allows to insert a constant element between each pair of elements in a sequence. Kind of what String.Join does for strings, but maintaining an enumerable as the return value. Having done the single element part I got a bit carried away and ended up expanding it adding overloads to support interleaving elements of another sequence and support for a predicate to control when interleaving takes place. I have to confess that I did this for fun and now I can’t think of any real usage scenario, nonetheless, it may prove useful for someone. First a simple example: var target = new string[] { "(", ")", "(", ")" }; var result = target.Interleave(".", (f, s) => f == "("); // Prints: (.)(.) Console.WriteLine(String.Join(string.Empty, result)); And now the untested but documented implementation: using System; using System.Collections; using System.Collections.Generic; using System.Linq; public static class EnumerableExtensions { /// <summary> /// Iterates infinitely over a constant element. /// </summary> /// <typeparam name="T"> /// The type of element in the sequence. /// </typeparam> private class InfiniteSequence<T> : IEnumerable<T>, IEnumerator<T> { public InfiniteSequence(T element) { this.Element = element; } public T Element { get; private set; } public IEnumerator<T> GetEnumerator() { return this; } IEnumerator IEnumerable.GetEnumerator() { return this; } T IEnumerator<T>.Current { get { return this.Element; } } void IDisposable.Dispose() { } object IEnumerator.Current { get { return this.Element; } } bool IEnumerator.MoveNext() { return true; } void IEnumerator.Reset() { } } /// <summary> /// Interleaves the specified <paramref name="element"/> between each pair of elements in the <paramref name="target"/> sequence. /// </summary> /// <typeparam name="T"> /// The type of elements in the sequence. /// </typeparam> /// <param name="target"> /// The target sequence to be interleaved. /// </param> /// <param name="element"> /// The element used to perform the interleave operation. /// </param> /// <exception cref="ArgumentNullException"> /// <paramref name="target"/> or <paramref name="element"/> is a null reference. /// </exception> /// <returns> /// The <paramref name="target"/> sequence interleaved with the specified <paramref name="element"/>. /// </returns> public static IEnumerable<T> Interleave<T>( this IEnumerable<T> target, T element) { if (target == null) throw new ArgumentNullException("target"); if (element == null) throw new ArgumentNullException("element"); return InterleaveInternal(target, new InfiniteSequence<T>(element), (f, s) => true); } /// <summary> /// Interleaves the specified <paramref name="element"/> between each pair of elements in the <paramref name="target"/> sequence. /// </summary> /// <remarks> /// The interleave operation is interrupted as soon as the <paramref name="target"/> sequence is exhausted; If the number of <paramref name="elements"/> to be interleaved are not enough to completely interleave the <paramref name="target"/> sequence then the remainder of the sequence is returned without being interleaved. /// </remarks> /// <typeparam name="T"> /// The type of elements in the sequence. /// </typeparam> /// <param name="target"> /// The target sequence to be interleaved. /// </param> /// <param name="elements"> /// The elements used to perform the interleave operation. /// </param> /// <exception cref="ArgumentNullException"> /// <paramref name="target"/> or <paramref name="element"/> is a null reference. /// </exception> /// <returns> /// The <paramref name="target"/> sequence interleaved with the specified <paramref name="elements"/>. /// </returns> public static IEnumerable<T> Interleave<T>( this IEnumerable<T> target, IEnumerable<T> elements) { if (target == null) throw new ArgumentNullException("target"); if (elements == null) throw new ArgumentNullException("elements"); return InterleaveInternal(target, elements, (f, s) => true); } /// <summary> /// Interleaves the specified <paramref name="element"/> between each pair of elements in the <paramref name="target"/> sequence that satisfy <paramref name="predicate"/>. /// </summary> /// <typeparam name="T"> /// The type of elements in the sequence. /// </typeparam> /// <param name="target"> /// The target sequence to be interleaved. /// </param> /// <param name="element"> /// The element used to perform the interleave operation. /// </param> /// <param name="predicate"> /// A predicate used to assert if interleaving should occur between two target elements. /// </param> /// <exception cref="ArgumentNullException"> /// <paramref name="target"/> or <paramref name="element"/> or <paramref name="predicate"/> is a null reference. /// </exception> /// <returns> /// The <paramref name="target"/> sequence interleaved with the specified <paramref name="element"/>. /// </returns> public static IEnumerable<T> Interleave<T>( this IEnumerable<T> target, T element, Func<T, T, bool> predicate) { if (target == null) throw new ArgumentNullException("target"); if (element == null) throw new ArgumentNullException("element"); if (predicate == null) throw new ArgumentNullException("predicate"); return InterleaveInternal(target, new InfiniteSequence<T>(element), predicate); } /// <summary> /// Interleaves the specified <paramref name="element"/> between each pair of elements in the <paramref name="target"/> sequence that satisfy <paramref name="predicate"/>. /// </summary> /// <remarks> /// The interleave operation is interrupted as soon as the <paramref name="target"/> sequence is exhausted; If the number of <paramref name="elements"/> to be interleaved are not enough to completely interleave the <paramref name="target"/> sequence then the remainder of the sequence is returned without being interleaved. /// </remarks> /// <typeparam name="T"> /// The type of elements in the sequence. /// </typeparam> /// <param name="target"> /// The target sequence to be interleaved. /// </param> /// <param name="elements"> /// The elements used to perform the interleave operation. /// </param> /// <param name="predicate"> /// A predicate used to assert if interleaving should occur between two target elements. /// </param> /// <exception cref="ArgumentNullException"> /// <paramref name="target"/> or <paramref name="element"/> or <paramref name="predicate"/> is a null reference. /// </exception> /// <returns> /// The <paramref name="target"/> sequence interleaved with the specified <paramref name="elements"/>. /// </returns> public static IEnumerable<T> Interleave<T>( this IEnumerable<T> target, IEnumerable<T> elements, Func<T, T, bool> predicate) { if (target == null) throw new ArgumentNullException("target"); if (elements == null) throw new ArgumentNullException("elements"); if (predicate == null) throw new ArgumentNullException("predicate"); return InterleaveInternal(target, elements, predicate); } private static IEnumerable<T> InterleaveInternal<T>( this IEnumerable<T> target, IEnumerable<T> elements, Func<T, T, bool> predicate) { var targetEnumerator = target.GetEnumerator(); if (targetEnumerator.MoveNext()) { var elementsEnumerator = elements.GetEnumerator(); while (true) { T first = targetEnumerator.Current; yield return first; if (!targetEnumerator.MoveNext()) yield break; T second = targetEnumerator.Current; bool interleave = true && predicate(first, second) && elementsEnumerator.MoveNext(); if (interleave) yield return elementsEnumerator.Current; } } } }

  Read the article

• How can I bind a custom color to WPF toolkit ColorPicker? [on hold]

  - by tube-builder

  I need to bind the SelectedColor property of ColorPicker to a custom color which is not present in available colors. I created a simple test to show my problem. My xaml: <xctk:ColorPicker SelectedColor="{Binding Path=Test}"></xctk:ColorPicker> Code behind (CurrentStyle.PenColor returns an integer value which equals 13109765): public Color Test { get; set; } public MyClass() { DataContext = this; Test = Color.FromArgb((byte)((CurrentStyle.PenColor >> 24) & 0xFF), (byte)((CurrentStyle.PenColor >> 16) & 0xFF), (byte)((CurrentStyle.PenColor >> 8) & 0xFF), (byte)(CurrentStyle.PenColor & 0xFF)); InitializeComponent(); } And that's how my ColorPicker looks like when the window is loaded (I don't have enough rep to post images so it's just links): http://s22.postimg.org/frzh2fgy9/image.png Though, when I go to Advanced colors I can see that the color has been recognized and set correctly. Here is a pic: http://s13.postimg.org/gjv4cmy07/image.png Hope for your help. Thanks a lot! EDIT I implemented INotifyPropertyChanged, still to no avail. Here's the code: public Color Test { get { return test; } set { if (test != value) { test = value; OnPropertyChanged("Test"); } } } public event PropertyChangedEventHandler PropertyChanged; protected void OnPropertyChanged(string prop) { if (this.PropertyChanged != null) this.PropertyChanged(this, new PropertyChangedEventArgs(prop)); } Maybe I'm doing smth wrong here.

  Read the article

• How do I make time?

  - by SystemNetworks

  I wanted to output a text for a certain amount of time. One way is to use threads. Are there any other ways? I can't use threads for slick2d. This is my code when I use threads for slick: package javagame; import org.newdawn.slick.GameContainer; import org.newdawn.slick.Graphics; import org.newdawn.slick.Image; import java.util.Random; import org.newdawn.slick.Input; import org.newdawn.slick.*; import org.newdawn.slick.state.*; import org.lwjgl.input.Mouse; public class thread1 implements Runnable { String showUp; int timeLeft; public thread1(String s) { s = showUp; } public void run(Graphics g) { try { g.drawString("%s is sleeping %d", 500, 500); Thread.sleep(timeLeft); g.drawString("%s is awake", 600,600); } catch(Exception e) { } } @Override public void run() { // TODO Auto-generated method stub run(); } } It auto generates a new run() And also when I call it to my main class it has stack overflow!

  Read the article

• Gap in parallaxing background loop

  - by CinetiK

  The bug here is that my background kind of offset a bit itself from where it should draw and so I have this line. I have some troubles understanding why I get this bug when I set a speed that is different then 1,2,4,8,16,... In main class I set the speed depending on the player speed bgSpeed = -(int)playerMoveSpeed.X / 10; and here's my background class class ParallaxingBackground { Texture2D texture; Vector2[] positions; public int Speed { get; set;} public void Initialize(ContentManager content, String texturePath, int screenWidth, int speed) { texture = content.Load<Texture2D>(texturePath); this.Speed = speed; positions = new Vector2[screenWidth / texture.Width + 2]; for (int i = 0; i < positions.Length; i++) { positions[i] = new Vector2(i * texture.Width, 0); } } public void Update() { for (int i = 0; i < positions.Length; i++) { positions[i].X += Speed; if (Speed <= 0) { if (positions[i].X <= -texture.Width) { positions[i].X = texture.Width * (positions.Length - 1); } } else { if (positions[i].X >= texture.Width*(positions.Length - 1)) { positions[i].X = -texture.Width; } } } } public void Draw(SpriteBatch spriteBatch) { for (int i = 0; i < positions.Length; i++) { spriteBatch.Draw(texture, positions[i], Color.White); } } }

  Read the article

• Why the R# Method Group Refactoring is Evil

  - by Liam McLennan

  The refactoring I’m talking about is recommended by resharper when it sees a lambda that consists entirely of a method call that is passed the object that is the parameter to the lambda. Here is an example: public class IWishIWasAScriptingLanguage { public void SoIWouldntNeedAllThisJunk() { (new List<int> {1, 2, 3, 4}).Select(n => IsEven(n)); } private bool IsEven(int number) { return number%2 == 0; } } When resharper gets to n => IsEven(n) it underlines the lambda with a green squiggly telling me that the code can be replaced with a method group. If I apply the refactoring the code becomes: public class IWishIWasAScriptingLanguage { public void SoIWouldntNeedAllThisJunk() { (new List<int> {1, 2, 3, 4}).Select(IsEven); } private bool IsEven(int number) { return number%2 == 0; } } The method group syntax implies that the lambda’s parameter is the same as the IsEven method’s parameter. So a readable, explicit syntax has been replaced with an obfuscated, implicit syntax. That is why the method group refactoring is evil.

  Read the article

• How to do dependency Injection and conditional object creation based on type?

  - by Pradeep

  I have a service endpoint initialized using DI. It is of the following style. This end point is used across the app. public class CustomerService : ICustomerService { private IValidationService ValidationService { get; set; } private ICustomerRepository Repository { get; set; } public CustomerService(IValidationService validationService,ICustomerRepository repository) { ValidationService = validationService; Repository = repository; } public void Save(CustomerDTO customer) { if (ValidationService.Valid(customer)) Repository.Save(customer); } Now, With the changing requirements, there are going to be different types of customers (Legacy/Regular). The requirement is based on the type of the customer I have to validate and persist the customer in a different way (e.g. if Legacy customer persist to LegacyRepository). The wrong way to do this will be to break DI and do somthing like public void Save(CustomerDTO customer) { if(customer.Type == CustomerTypes.Legacy) { if (LegacyValidationService.Valid(customer)) LegacyRepository.Save(customer); } else { if (ValidationService.Valid(customer)) Repository.Save(customer); } } My options to me seems like DI all possible IValidationService and ICustomerRepository and switch based on type, which seems wrong. The other is to change the service signature to Save(IValidationService validation, ICustomerRepository repository, CustomerDTO customer) which is an invasive change. Break DI. Use the Strategy pattern approach for each type and do something like: validation= CustomerValidationServiceFactory.GetStratedgy(customer.Type); validation.Valid(customer) but now I have a static method which needs to know how to initialize different services. I am sure this is a very common problem, What is the right way to solve this without changing service signatures or breaking DI?

  Read the article

• forward motion car physics - gradual slow

  - by spartan2417

  Im having trouble creating realistic car movements in xna 4. Right now i have a car going forward and hitting a terminal velocity which is fine but when i release the up key i need to the car to slow down gradually and then come to a stop. Im pretty sure this is easy code but i cant seem to get it to work the code - update if (Keyboard.GetState().IsKeyDown(Keys.Up)) { double elapsedTime = gameTime.ElapsedGameTime.Milliseconds; CalcTotalForce(); Acceleration = Vector2.Divide(CalcTotalForce(), MASS); Velocity = Vector2.Add(Velocity, Vector2.Multiply(Acceleration, (float)(elapsedTime))); Position = Vector2.Add(Position, Vector2.Multiply(Velocity, (float)(elapsedTime))); } added functions public Vector2 CalcTraction() { //Traction force = vector direction * engine force return Vector2.Multiply(forwardDirection, ENGINE_FORCE); } public Vector2 CalcDrag() { //Drag force = constdrag * velocity * speed return Vector2.Multiply(Vector2.Multiply(Velocity, DRAG_CONST), Velocity.Y); } public Vector2 CalcRoll() { //roll force = const roll * velocity return Vector2.Multiply(Velocity, ROLL_CONST); } public Vector2 CalcTotalForce() { //total force = traction + (-drag) + (-rolling) return Vector2.Add(CalcTraction(), Vector2.Add(-CalcDrag(), -CalcRoll())); } anyone have any ideas?

  Read the article

• Using PDO with MVC

  - by mister martin

  I asked this question at stackoverflow and received no response (closed as duplicate with no answer). I'm experimenting with OOP and I have the following basic MVC layout: class Model { // do database stuff } class View { public function load($filename, $data = array()) { if(!empty($data)) { extract($data); } require_once('views/header.php'); require_once("views/$filename"); require_once('views/footer.php'); } } class Controller { public $model; public $view; function __construct() { $this->model = new Model(); $this->view = new View(); // determine what page we're on $page = isset($_GET['view']) ? $_GET['view'] : 'home'; $this->display($page); } public function display($page) { switch($page) { case 'home': $this->view->load('home.php'); break; } } } These classes are brought together in my setup file: // start session session_start(); require_once('Model.php'); require_once('View.php'); require_once('Controller.php'); new Controller(); Now where do I place my database connection code and how do I pass the connection onto the model? try { $db = new PDO('mysql:host='.DB_HOST.';dbname='.DB_DATABASE.'', DB_USERNAME, DB_PASSWORD); $db->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION); } catch(PDOException $err) { die($err->getMessage()); } I've read about Dependency Injection, factories and miscellaneous other design patterns talking about keeping SQL out of the model, but it's all over my head using abstract examples. Can someone please just show me a straight-forward practical example?

  Read the article

< Previous Page | 192 193 194 195 196 197 198 199 200 201 202 203  | Next Page >