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  • What do you need to know to be a world-class master software developer? [closed]

    - by glitch
    I wanted to bring up this question to you folks and see what you think, hopefully advise me on the matter: let's say you had 30 years of learning and practicing software development in front of you, how would you dedicate your time so that you'd get the biggest bang for your buck. What would you both learn and work on to be a world-class software developer that would make a large impact on the industry and leave behind a legacy? I think that most great developers end up being both broad generalists and specialists in one-two areas of interest. I'm thinking Bill Joy, John Carmack, Linus Torvalds, K&R and so on. I'm thinking that perhaps one approach would be to break things down by categories and establish a base minimum of "software development" greatness. I'm thinking: Operating Systems: completely internalize the core concepts of OS, perhaps gain a lot of familiarity with an OSS one such as Linux. Anything from memory management to device drivers has to be complete second nature. Programming Languages: this is one of those topics that imho has to be fully grokked even if it might take many years. I don't think there's quite anything like going through the process of developing your own compiler, understanding language design trade-offs and so on. Programming Language Pragmatics is one of my favorite books actually, I think you want to have that internalized back to back, and that's just the start. You could go significantly deeper, but I think it's time well spent, because it's such a crucial building block. As a subset of that, you want to really understand the different programming paradigms out there. Imperative, declarative, logic, functional and so on. Anything from assembly to LISP should be at the very least comfortable to write in. Contexts: I believe one should have experience working in different contexts to truly be able to appreciate the trade-offs that are being made every day. Embedded, web development, mobile development, UX development, distributed, cloud computing and so on. Hardware: I'm somewhat conflicted about this one. I think you want some understanding of computer architecture at a low level, but I feel like the concepts that will truly matter will be slightly higher level, such as CPU caching / memory hierarchy, ILP, and so on. Networking: we live in a completely network-dependent era. Having a good understanding of the OSI model, knowing how the Web works, how HTTP works and so on is pretty much a pre-requisite these days. Distributed systems: once again, everything's distributed these days, it's getting progressively harder to ignore this reality. Slightly related, perhaps add solid understanding of how browsers work to that, since the world seems to be moving so much to interfacing with everything through a browser. Tools: Have a really broad toolset that you're familiar with, one that continuously expands throughout the years. Communication: I think being a great writer, effective communicator and a phenomenal team player is pretty much a prerequisite for a lot of a software developer's greatness. It can't be overstated. Software engineering: understanding the process of building software, team dynamics, the requirements of the business-side, all the pitfalls. You want to deeply understand where what you're writing fits from the market perspective. The better you understand all of this, the more of your work will actually see the daylight. This is really just a starting list, I'm confident that there's a ton of other material that you need to master. As I mentioned, you most likely end up specializing in a bunch of these areas as you go along, but I was trying to come up with a baseline. Any thoughts, suggestions and words of wisdom from the grizzled veterans out there who would like to share their thoughts and experiences with this? I'd really love to know what you think!

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  • Don’t string together XML

    - by KyleBurns
    XML has been a pervasive tool in software development for over a decade.  It provides a way to communicate data in a manner that is simple to understand and free of platform dependencies.  Also pervasive in software development is what I consider to be the anti-pattern of using string manipulation to create XML.  This usually starts with a “quick and dirty” approach because you need an XML document and looks like (for all of the examples here, we’ll assume we’re writing the body of a method intended to take a Contact object and return an XML string): return string.Format("<Contact><BusinessName>{0}</BusinessName></Contact>", contact.BusinessName);   In the code example, I created (or at least believe I created) an XML document representing a simple contact object in one line of code with very little overhead.  Work’s done, right?  No it’s not.  You see, what I didn’t realize was that this code would be used in the real world instead of my fantasy world where I own all the data and can prevent any of it containing problematic values.  If I use this code to create a contact record for the business “Sanford & Son”, any XML parser will be incapable of processing the data because the ampersand is special in XML and should have been encoded as &amp;. Following the pattern that I have seen many times over, my next step as a developer is going to be to do what any developer in his right mind would do – instruct the user that ampersands are “bad” and they cannot be used without breaking computers.  This may work in many cases and is often accompanied by logic at the UI layer of applications to block these “bad” characters, but sooner or later someone is going to figure out that other applications allow for them and will want the same.  This often leads to the creation of “cleaner” functions that perform a replace on the strings for every special character that the person writing the function can think of.  The cleaner function will usually grow over time as support requests reveal characters that were missed in the initial cut.  Sooner or later you end up writing your own somewhat functional XML engine. I have never been told by anyone paying me to write code that they would like to buy a somewhat functional XML engine.  My employer/customer’s needs have always been for something that may use XML, but ultimately is functionality that drives business value. I’m not going to build an XML engine. So how can I generate XML that is always well-formed without writing my own engine?  Easy – use one of the ones provided to you for free!  If you’re in a shop that still supports VB6 applications, you can use the DomDocument or MXXMLWriter object (of the two I prefer MXXMLWriter, but I’m not going to fully describe either here).  For .Net Framework applications prior to the 3.5 framework, the code is a little more verbose than I would like, but easy once you understand what pieces are required:             using (StringWriter sw = new StringWriter())             {                 using (XmlTextWriter writer = new XmlTextWriter(sw))                 {                     writer.WriteStartDocument();                     writer.WriteStartElement("Contact");                     writer.WriteElementString("BusinessName", contact.BusinessName);                     writer.WriteEndElement(); // end Contact element                     writer.WriteEndDocument();                     writer.Flush();                     return sw.ToString();                 }             }   Looking at that code, it’s easy to understand why people are drawn to the initial one-liner.  Lucky for us, the 3.5 .Net Framework added the System.Xml.Linq.XElement object.  This object takes away a lot of the complexity present in the XmlTextWriter approach and allows us to generate the document as follows: return new XElement("Contact", new XElement("BusinessName", contact.BusinessName)).ToString();   While it is very common for people to use string manipulation to create XML, I’ve discussed here reasons not to use this method and introduced powerful APIs that are built into the .Net Framework as an alternative.  I’ve given a very simplistic example here to highlight the most basic XML generation task.  For more information on the XmlTextWriter and XElement APIs, check out the MSDN library.

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  • Multitenancy in SQL Azure

    - by cibrax
    If you are building a SaaS application in Windows Azure that relies on SQL Azure, it’s probably that you will need to support multiple tenants at database level. This is short overview of the different approaches you can use for support that scenario, A different database per tenant A new database is created and assigned when a tenant is provisioned. Pros Complete isolation between tenants. All the data for a tenant lives in a database only he can access. Cons It’s not cost effective. SQL Azure databases are not cheap, and the minimum size for a database is 1GB.  You might be paying for storage that you don’t really use. A different connection pool is required per database. Updates must be replicated across all the databases You need multiple backup strategies across all the databases Multiple schemas in a database shared by all the tenants A single database is shared among all the tenants, but every tenant is assigned to a different schema and database user. Pros You only pay for a single database. Data is isolated at database level. If the credentials for one tenant is compromised, the rest of the data for the other tenants is not. Cons You need to replicate all the database objects in every schema, so the number of objects can increase indefinitely. Updates must be replicated across all the schemas. The connection pool for the database must maintain a different connection per tenant (or set of credentials) A different user is required per tenant, which is stored at server level. You have to backup that user independently. Centralizing the database access with store procedures in a database shared by all the tenants A single database is shared among all the tenants, but nobody can read the data directly from the tables. All the data operations are performed through store procedures that centralize the access to the tenant data. The store procedures contain some logic to map the database user to an specific tenant. Pros You only pay for a single database. You only have a set of objects to maintain and backup. Cons There is no real isolation. All the data for the different tenants is shared in the same tables. You can not use traditional ORM like EF code first for consuming the data. A different user is required per tenant, which is stored at server level. You have to backup that user independently. SQL Federations A single database is shared among all the tenants, but a different federation is used per tenant. A federation in few words, it’s a mechanism for horizontal scaling in SQL Azure, which basically uses the idea of logical partitions to distribute data based on certain criteria. Pros You only have a single database with multiple federations. You can use filtering in the connections to pick the right federation, so any ORM could be used to consume the data. Cons There is no real isolation at that database level. The isolation is enforced programmatically with federations.

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  • Is my class structure good enough?

    - by Rivten
    So I wanted to try out this challenge on reddit which is mostly about how you structure your data the best you can. I decided to challenge my C++ skills. Here's how I planned this. First, there's the Game class. It deals with time and is the only class main has access to. A game has a Forest. For now, this class does not have a lot of things, only a size and a Factory. Will be put in better use when it will come to SDL-stuff I guess A Factory is the thing that deals with the Game Objects (a.k.a. Trees, Lumberjack and Bears). It has a vector of all GameObjects and a queue of Events which will be managed at the end of one month. A GameObject is an abstract class which can be updated and which can notify the Event Listener The EventListener is a class which handles all the Events of a simulation. It can recieve events from a Game Object and notify the Factory if needed, the latter will manage correctly the event. So, the Tree, Lumberjack and Bear classes all inherits from GameObject. And Sapling and Elder Tree inherits from Tree. Finally, an Event is defined by an event_type enumeration (LUMBERJACK_MAWED, SAPPLING_EVOLUTION, ...) and an event_protagonists union (a GameObject or a pair of GameObject (who killed who ?)). I was quite happy at first with this because it seems quite logic and flexible. But I ended up questionning this structure. Here's why : I dislike the fact that a GameObject need to know about the Factory. Indeed, when a Bear moves somewhere, it needs to know if there's a Lumberjack ! Or it is the Factory which handles places and objects. It would be great if a GameObject could only interact with the EventListener... or maybe it's not that much of a big deal. Wouldn't it be better if I separate the Factory in three vectors ? One for each kind of GameObject. The idea would be to optimize research. If I'm looking do delete a dead lumberjack, I would only have to look in one shorter vector rather than a very long vector. Another problem arises when I want to know if there is any particular object in a given case because I have to look for all the gameObjects and see if they are at the given case. I would tend to think that the other idea would be to use a matrix but then the issue would be that I would have empty cases (and therefore unused space). I don't really know if Sapling and Elder Tree should inherit from Tree. Indeed, a Sapling is a Tree but what about its evolution ? Should I just delete the sapling and say to the factory to create a new Tree at the exact same place ? It doesn't seem natural to me to do so. How could I improve this ? Is the design of an Event quite good ? I've never used unions before in C++ but I didn't have any other ideas about what to use. Well, I hope I have been clear enough. Thank you for taking the time to help me !

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  • Z axis trouble with glTranslatef(...) - LWJGL

    - by Zarkopafilis
    Here is the code: private static boolean up = true , down = false , left = false , right = false, reset = false, in = false , out = false; public void start() { try { Display.setDisplayMode(new DisplayMode(800,600)); Display.create(); } catch (LWJGLException e) { e.printStackTrace(); System.exit(0); } GL11.glMatrixMode(GL11.GL_PROJECTION); GL11.glLoadIdentity(); GL11.glOrtho(0, 800, 0, 600, 0.00001f, 1000); GL11.glMatrixMode(GL11.GL_MODELVIEW); Keyboard.enableRepeatEvents(true); while (!Display.isCloseRequested()) { GL11.glClear(GL11.GL_COLOR_BUFFER_BIT); input(); if(up){ GL11.glTranslatef(0,0.1f,0); } if(down){ GL11.glTranslatef(0,-0.1f,0); } if(left){ GL11.glTranslatef(-0.1f,0,0); } if(right){ GL11.glTranslatef(0.1f,0,0); } if(in){ GL11.glTranslatef(0, 0, 1f); } if(out){ GL11.glTranslatef(0, 0, -1f); } if(reset){ GL11.glLoadIdentity(); } GL11.glBegin(GL11.GL_QUADS); GL11.glColor3f(255, 255, 255); GL11.glVertex3f(800/2, 600/2, 0); GL11.glVertex3f(800/2 + 200, 600/2, 0); GL11.glVertex3f(800/2 + 200, 600/2 + 200, 0); GL11.glVertex3f(800/2, 600/2 + 200, 0); GL11.glColor3f(0, 255, 0); GL11.glVertex3f(800/2, 600/2, 1); GL11.glVertex3f(800/2 + 200, 600/2, 1); GL11.glVertex3f(800/2 + 200, 600/2 + 200, 1); GL11.glVertex3f(800/2, 600/2 + 200, 1); GL11.glEnd(); Display.update(); } Display.destroy(); } public static void main(String[] argv){ new main().start(); } public void input(){ up = false; down = false; left = false; right = false; reset = false; in = false; out = false; if(Keyboard.isKeyDown(Keyboard.KEY_SPACE)){ reset = true; } if(Keyboard.isKeyDown(Keyboard.KEY_W)){ up = true; } if(Keyboard.isKeyDown(Keyboard.KEY_S)){ down = true; } if(Keyboard.isKeyDown(Keyboard.KEY_A)){ left = true; } if(Keyboard.isKeyDown(Keyboard.KEY_D)){ right = true; } if(Keyboard.isKeyDown(Keyboard.KEY_Q)){ in = true; } if(Keyboard.isKeyDown(Keyboard.KEY_E)){ out = true; } } As you can see I am creating 2 quads , a white one at z 0 and a green one at z 1. WASD keys function correctly. Also when I hit SPACEBAR the white quad is being shown. If I then press E , I can see the green quad. But if I press Q afterwards , I dont see the white one again!(Space Works everytime). Also if I render the green one at Z = -1 everything works perfectly BUT you may need up to 3 key presses Q/E to see the other quad. Why is that happening?

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  • android client not working [migrated]

    - by Syeda Zunairah
    i have a java client and c# server the server code is static Socket listeningSocket; static Socket socket; static Thread thrReadRequest; static int iPort = 4444; static int iConnectionQueue = 100; static void Main(string[] args) { Console.WriteLine(IPAddress.Parse(getLocalIPAddress()).ToString()); try { listeningSocket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp); //listeningSocket.Bind(new IPEndPoint(0, iPort)); listeningSocket.Bind(new IPEndPoint(IPAddress.Parse(getLocalIPAddress()), iPort)); listeningSocket.Listen(iConnectionQueue); thrReadRequest = new Thread(new ThreadStart(getRequest)); thrReadRequest.Start(); } catch (Exception e) { Console.WriteLine("Winsock error: " + e.ToString()); //throw; } } static private void getRequest() { int i = 0; while (true) { i++; Console.WriteLine("Outside Try i = {0}", i.ToString()); try { socket = listeningSocket.Accept(); // Receiving //byte[] rcvLenBytes = new byte[4]; //socket.Receive(rcvLenBytes); //int rcvLen = System.BitConverter.ToInt32(rcvLenBytes, 0); //byte[] rcvBytes = new byte[rcvLen]; //socket.Receive(rcvBytes); //String formattedBuffer = System.Text.Encoding.ASCII.GetString(rcvBytes); byte[] buffer = new byte[socket.SendBufferSize]; int iBufferLength = socket.Receive(buffer, 0, buffer.Length, 0); Console.WriteLine("Received {0}", iBufferLength); Array.Resize(ref buffer, iBufferLength); string formattedBuffer = Encoding.ASCII.GetString(buffer); Console.WriteLine("Data received by Client: {0}", formattedBuffer); if (formattedBuffer == "quit") { socket.Close(); listeningSocket.Close(); Environment.Exit(0); } Console.WriteLine("Inside Try i = {0}", i.ToString()); Thread.Sleep(500); } catch (Exception e) { //socket.Close(); Console.WriteLine("Receiving error: " + e.ToString()); Console.ReadKey(); //throw; } finally { socket.Close(); //listeningsocket.close(); } } } static private string getLocalIPAddress() { IPHostEntry host; string localIP = ""; host = Dns.GetHostEntry(Dns.GetHostName()); foreach (IPAddress ip in host.AddressList) { if (ip.AddressFamily == AddressFamily.InterNetwork) { localIP = ip.ToString(); break; } } return localIP; } } and the jave android code is private TCPClient mTcpClient; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); final EditText editText = (EditText) findViewById(R.id.edit_message); Button send = (Button)findViewById(R.id.sendbutton); // connect to the server new connectTask().execute(""); send.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View view) { String message = editText.getText().toString(); //sends the message to the server if (mTcpClient != null) { mTcpClient.sendMessage(message); } editText.setText(""); } }); } @Override public boolean onCreateOptionsMenu(Menu menu) { getMenuInflater().inflate(R.menu.main, menu); return true; } public class connectTask extends AsyncTask<String,String,TCPClient> { @Override protected TCPClient doInBackground(String... message) { mTcpClient = new TCPClient(new TCPClient.OnMessageReceived() { @Override public void messageReceived(String message) { publishProgress(message); } }); mTcpClient.run(); return null; } @Override protected void onProgressUpdate(String... values) { super.onProgressUpdate(values); } } } when i run the server it gives output of try i=1. can any one tell me what to do next

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  • Why is 0 false?

    - by Morwenn
    This question may sound dumb, but why does 0 evaluates to false and any other [integer] value to true is most of programming languages? String comparison Since the question seems a little bit too simple, I will explain myself a little bit more: first of all, it may seem evident to any programmer, but why wouldn't there be a programming language - there may actually be, but not any I used - where 0 evaluates to true and all the other [integer] values to false? That one remark may seem random, but I have a few examples where it may have been a good idea. First of all, let's take the example of strings three-way comparison, I will take C's strcmp as example: any programmer trying C as his first language may be tempted to write the following code: if (strcmp(str1, str2)) { // Do something... } Since strcmp returns 0 which evaluates to false when the strings are equal, what the beginning programmer tried to do fails miserably and he generally does not understand why at first. Had 0 evaluated to true instead, this function could have been used in its most simple expression - the one above - when comparing for equality, and the proper checks for -1 and 1 would have been done only when needed. We would have considered the return type as bool (in our minds I mean) most of the time. Moreover, let's introduce a new type, sign, that just takes values -1, 0 and 1. That can be pretty handy. Imagine there is a spaceship operator in C++ and we want it for std::string (well, there already is the compare function, but spaceship operator is more fun). The declaration would currently be the following one: sign operator<=>(const std::string& lhs, const std::string& rhs); Had 0 been evaluated to true, the spaceship operator wouldn't even exist, and we could have declared operator== that way: sign operator==(const std::string& lhs, const std::string& rhs); This operator== would have handled three-way comparison at once, and could still be used to perform the following check while still being able to check which string is lexicographically superior to the other when needed: if (str1 == str2) { // Do something... } Old errors handling We now have exceptions, so this part only applies to the old languages where no such thing exist (C for example). If we look at C's standard library (and POSIX one too), we can see for sure that maaaaany functions return 0 when successful and any integer otherwise. I have sadly seen some people do this kind of things: #define TRUE 0 // ... if (some_function() == TRUE) { // Here, TRUE would mean success... // Do something } If we think about how we think in programming, we often have the following reasoning pattern: Do something Did it work? Yes -> That's ok, one case to handle No -> Why? Many cases to handle If we think about it again, it would have made sense to put the only neutral value, 0, to yes (and that's how C's functions work), while all the other values can be there to solve the many cases of the no. However, in all the programming languages I know (except maybe some experimental esotheric languages), that yes evaluates to false in an if condition, while all the no cases evaluate to true. There are many situations when "it works" represents one case while "it does not work" represents many probable causes. If we think about it that way, having 0 evaluate to true and the rest to false would have made much more sense. Conclusion My conclusion is essentially my original question: why did we design languages where 0 is false and the other values are true, taking in account my few examples above and maybe some more I did not think of? Follow-up: It's nice to see there are many answers with many ideas and as many possible reasons for it to be like that. I love how passionate you seem to be about it. I originaly asked this question out of boredom, but since you seem so passionate, I decided to go a little further and ask about the rationale behind the Boolean choice for 0 and 1 on Math.SE :)

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  • Server cannot set status after HTTP headers have been sent IIS7.5

    - by marcinn
    Hi, Sometimes I get exception in my production environment: Process information Process ID: 3832 Process name: w3wp.exe Account name: NT AUTHORITY\NETWORK SERVICE Exception information Exception type: System.Web.HttpException Exception message: Server cannot set status after HTTP headers have been sent. Request information Request URL: http://www.myulr.pl/logon Request path: /logon User host address: 10.11.9.1 User: user001 Is authenticated: True Authentication Type: Forms Thread account name: NT AUTHORITY\NETWORK SERVICE Thread information Thread ID: 10 Thread account name: NT AUTHORITY\NETWORK SERVICE Is impersonating: False Stack trace: at System.Web.HttpResponse.set_StatusCode(Int32 value) at System.Web.HttpResponseWrapper.set_StatusCode(Int32 value) at System.Web.Mvc.HandleErrorAttribute.OnException(ExceptionContext filterContext) at System.Web.Mvc.ControllerActionInvoker.InvokeExceptionFilters(ControllerContext controllerContext, IList(1) filters, Exception exception) at System.Web.Mvc.ControllerActionInvoker.InvokeAction(ControllerContext controllerContext, String actionName) at System.Web.Mvc.Controller.ExecuteCore() at System.Web.Mvc.MvcHandler.<>c__DisplayClass8.<BeginProcessRequest>b__4() at System.Web.Mvc.Async.AsyncResultWrapper.<>c__DisplayClass1.<MakeVoidDelegate>b__0() at System.Web.Mvc.Async.AsyncResultWrapper.<>c__DisplayClass8(1).<BeginSynchronous>b__7(IAsyncResult _) at System.Web.Mvc.Async.AsyncResultWrapper.WrappedAsyncResult(1).End() at System.Web.Mvc.MvcHandler.EndProcessRequest(IAsyncResult asyncResult) at System.Web.HttpApplication.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() at System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& ompletedSynchronously) I didn't noticed this error on my test environment what should I check? I am using ASP.NET MVC 2 (Release Candidate 2)

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  • System.Runtime.InteropServices.COMException (0x80070008): Not enough storage is available to process

    - by Darryl Braaten
    I am trying to diagnose this exception. "System.Runtime.InteropServices.COMException (0x80070008): Not enough storage is available to process this command. (Exception from HRESULT: 0x80070008) at System.Runtime.Remoting.RemotingServices.AllocateUninitializedObject(RuntimeType objectType) at System.Runtime.Remoting.RemotingServices.AllocateUninitializedObject(Type objectType) at System.Runtime.Remoting.Activation.ActivationServices.CreateInstance(Type serverType) at System.Runtime.Remoting.Activation.ActivationServices.IsCurrentContextOK(Type serverType, Object[] props, Boolean bNewObj) at Oracle.DataAccess.Client.CThreadPool..ctor() at Oracle.DataAccess.Client.OracleCommand.set_CommandTimeout(Int32 value) ... It does not look like any of the normal types of "storage" have hit any limits. The application is using about 400MB of memory, 70 threads, 2000 handles and the hard drive has many GB free. The machine is running Windows 2003 Enterprise server with 16GB of RAM so memory shouldn't be an issue. The application is running as a windows service so there are no GDI objects being used. Running out of GDI handles is a common cause of this exception. Database connections, commands & readers are all all wrapped with using blocks so they should be getting cleaned up correctly.

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  • Installing VSTO 4.0 Causes VSTO 3.0 Addin to quit working

    - by Jacob Adams
    I just installed Visual Studio 2010 yesterday. As part of that I installed VSTO 4.0. Now when I run any Office application, my VSTO 3.0 addins fail to load. The error in the event log is Customization URI: file:///H:/PathToMyAddin/MyAddin.vsto Exception: Customization does not have the permissions required to create an application domain. ***** Exception Text ******* Microsoft.VisualStudio.Tools.Applications.Runtime.CannotCreateCustomizationDomainException: Customization does not have the permissions required to create an application domain. --- System.Security.SecurityException: Customized functionality in this application will not work because the administrator has listed file:///H:/PathToMyAddin/MyAddin.vsto as untrusted. Contact your administrator for further assistance. at Microsoft.VisualStudio.Tools.Office.Runtime.RuntimeUtilities.VerifySolutionUri(Uri uri) at Microsoft.VisualStudio.Tools.Office.Runtime.DomainCreator.CreateCustomizationDomainInternal(String solutionLocation, String manifestName, String documentName, Boolean showUIDuringDeployment, IntPtr hostServiceProvider, IntPtr& executor) The Zone of the assembly that failed was: MyComputer It seems like like maybe this is due to it trying to load different version of .NET is the same process/AppDomain. However the error would indicate it's some sort of permissions issue.

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  • Listview Swipe inside viewflipper

    - by Faisal Abid
    Im trying to swipe left and right on a listview and get the viewflipper to swtich. Just like the remeberthemilk app and the default news and weather app on the nexus one (Swiping through news topics). Using various tutorials ive found , i came across on one stackoverflow that shows how to implement a swipe gesture class MyGestureDetector extends SimpleOnGestureListener { @Override public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX, float velocityY) { try { if (Math.abs(e1.getY() - e2.getY()) > SWIPE_MAX_OFF_PATH) return true; // right to left swipe if(e1.getX() - e2.getX() > SWIPE_MIN_DISTANCE && Math.abs(velocityX) > SWIPE_THRESHOLD_VELOCITY) { } else if (e2.getX() - e1.getX() > SWIPE_MIN_DISTANCE && Math.abs(velocityX) > SWIPE_THRESHOLD_VELOCITY) { viewFlipper.setInAnimation(slideRightIn); viewFlipper.setOutAnimation(slideRightOut); viewFlipper.showPrevious(); } } catch (Exception e) { // nothing } return true; } } And i got this working by doing lstView.setOnTouchListener(gestureListener); However sometimes what would happen is the listview setOnItemClickListener would be fired when the person is swiping. How do i prevent this from happening, and only get the setOnItemClickListener fired when the user actually clicks on it list item and not just swiping on it. Thanks, Faisal Abid

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  • Silverlight data binding to parent user control's properties with using MVVM in both controls

    - by MagicMax
    Hello! I have two UserControls ("UserControlParentView" and "UserControlChildView") with MVVM pattern implemented in both controls. Parent control is a container for Child control and child control's property should be updated by data binding from Parent control in order to show/hide some check box inside Child control. Parent Control Description UserControlParentViewModel has property: private bool isShowCheckbox = false; public bool IsShowCheckbox { get { return isShowCheckbox; } set { isShowCheckbox = value; NotifyPropertyChanged("IsShowCheckbox"); } } UserControlParentViewModel - how I set DataContext of Parent control: public UserControlParentView() { InitializeComponent(); this.DataContext = new UserControlParentViewModel(); } UserControlParentView contains toggle button (in XAML), bound to UserControlParentViewModel's property IsShowCheckbox <ToggleButton Grid.Column="1" IsChecked="{Binding IsShowCheckbox, Mode=TwoWay}"></ToggleButton> Also Parent control contains instance of child element (somewhere in XAML) <local:UserControlChildView IsCheckBoxVisible="{Binding IsShowCheckbox}" ></local:UserControlChildView> so property in child control should be updated when user togggle/untoggle button. Child control contains Boolean property to be updated from parent control, but nothing happened! Breakpoint never fired! Property in UserControlChildView that should be updated from Parent control (here I plan to make chechBox visible/hidden in code behind): public bool IsCheckBoxVisible { get { return (bool)GetValue(IsCheckBoxVisibleProperty); } set { SetValue(IsCheckBoxVisibleProperty, value); } } // Using a DependencyProperty as the backing store for IsCheckBoxVisible. This enables animation, styling, binding, etc... public static readonly DependencyProperty IsCheckBoxVisibleProperty = DependencyProperty.Register("IsCheckBoxVisible", typeof(bool), typeof(TopMenuButton), new PropertyMetadata(false)); So the question is - what I'm doing wrong? Why child's property is never updated? BTW - there is no any binding error warnings in Output window...

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  • Why do I get a DependencyProperty.UnsetValue when converting a value in a MultiBinding?

    - by eskerber
    I have an extremely simple IMultiValueConverter that simply OR's two values. In the example below, I want to invert the first value using an equally simple boolean inverter. <MultiBinding Converter="{StaticResource multiBoolToVis}"> <Binding Path="ConditionA" Converter="{StaticResource boolInverter}"/> <Binding Path="ConditionB"/> </MultiBinding> public class BoolInverterConverter : IValueConverter { #region IValueConverter Members public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture) { if (value is bool) { return !((bool)value); } return null; } public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture) { throw new NotImplementedException(); } #endregion } When I include the boolInverter, the first value in the MultiValueConverter becomes a "DependencyProperty.UnsetValue". There are no problems when I do not use the converter (other than not the logic I am aiming for, of course). Am I missing something? Stepping through the debugger shows that the InverseBoolConverter is properly inverting the value I pass it, but that value is then not being 'sent' to the MultiValueConverter.

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  • HTML Agility Pack - ReplaceNode doesn't change the InnerHTML of the Body

    - by morsanu
    Hi there, I have this The body: <body><p>Lorem ipsum dolor sit amet, consectetur adipiscing elit. Praesent leo leo, ultrices eu venenatis et, rutrum fringilla dolor.</p></body> The code: HtmlNode body = doc.DocumentNode.SelectSingleNode("//body"); Dictionary<HtmlNode, HtmlNode> toReplace = new Dictionary<HtmlNode, HtmlNode>(); // I do some logic here adding nodes to the toReplace dictionary. foreach (HtmlNode replaceNode in toReplace.Keys) { replaceNode.ParentNod.ReplaceChild(toReplace[replaceNode], replaceNode); } After i do this, the InnerHtml of the body node remains the same as from beginning, although the OutterHtml or the InnerText are showing the good result. Is there something wrong with my code? The result: // body.InnerHtml <p>Lorem ipsum dolor sit amet, consectetur adipiscing elit. Praesent leo leo, ultrices eu venenatis et, rutrum fringilla dolor.</p> // body.OutterHtml <body><p>Lorem ipsum dolor sit amet...</p></body>

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  • The HTTP verb POST used to access path '/' is not allowed.

    - by Ryan
    The entire error: Server Error in '/' Application. The HTTP verb POST used to access path '/' is not allowed. Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code. Exception Details: System.Web.HttpException: The HTTP verb POST used to access path '/' is not allowed. Source Error: An unhandled exception was generated during the execution of the current web request. Information regarding the origin and location of the exception can be identified using the exception stack trace below. Stack Trace: [HttpException (0x80004005): The HTTP verb POST used to access path '/' is not allowed.] System.Web.DefaultHttpHandler.BeginProcessRequest(HttpContext context, AsyncCallback callback, Object state) +2871966 System.Web.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() +8679410 System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) +155 To be honest, I'm not even sure where the error came from. I'm running Visual Studio 2008 through the Virtual Server. I just put a button: <asp:Button ID="btnRegister" runat="server" Text="Register" CssClass="bt_register" onclick="btnRegister_Click" /> On a login user control, the onclick event is just a simple response.redirect Response.Redirect("~/register.aspx"); Debugging the project, it isn't even hitting the btnRegister_Click method anyway. I'm not sure where to even begin with debugging this error. Any information will help. I can post all the code I have, but like I said, I'm not sure where this error is even being thrown at. Edit It has nothing at all to do with the button click event. I got rid of the method and the onclick parameter on the aspx page. Still coming up with the same error problem found Okay so this is for a school project and its a group project. Some one in my group thought it would be a good idea to wrap a form tag around this area telling it to post. Found it doing a diff with a revision on Google code.

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  • How do I get Lucene (.NET) to highlight correctly with wildcards?

    - by Scott Stafford
    I am using the Lucene.NET API directly in my ASP.NET/C# web application. When I search using a wildcard, like "fuc*", the highlighter doesn't highlight anything, but when I search for the whole word, like "fuchsia", it highlights fine. Does Lucene have the ability to highlight using the same logic it used to match with? Various maybe-relevant code-snippets below: var formatter = new Lucene.Net.Highlight.SimpleHTMLFormatter( "<span class='srhilite'>", "</span>"); var fragmenter = new Lucene.Net.Highlight.SimpleFragmenter(100); var scorer = new Lucene.Net.Highlight.QueryScorer(query); var highlighter = new Lucene.Net.Highlight.Highlighter(formatter, scorer); highlighter.SetTextFragmenter(fragmenter); and then on each hit... string description = Server.HtmlEncode(doc.Get("Description")); var stream = analyzer.TokenStream("Description", new System.IO.StringReader(description)); string highlighted_text = highlighter.GetBestFragments( stream, description, 1, "..."); And I'm using the QueryParser and the StandardAnalyzer.

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  • Stateful vs. Stateless Webservices

    - by chrsk
    Imagine a more complex CRUD application which has a three-tier-architecture and communicates over webservices. The client starts a conversation to the server and doing some wizard like stuff. To process the wizard the client needs feedback given by the server. We started a discussion about stateful or stateless webservices for this approach. I made some research combined with my own experience, which points me to the question mentioned later. Stateless webservices having the following properties (in our case): + high scalability + high availability + high speed + rapid testing - bloated contract - implementing more logic on server-side But we can cross out the first two points, our application doesn't needs high scalability and availability. So we come to the stateful webservice. I've read a bunch of blogs and forum posts and the most invented point implementing a stateful webservice was: + simplifies contract (protocol) - bad testing - runs counter to the basic architecture of http But doesn't almost all web applications have these bad points? Web applications uses cookies, query strings, session ids, and all the stuff to avoid the statelessness of http. So why is it that bad for webservices?

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  • ASP.NET MVC - dropdown list post handling problem

    - by ile
    I've had troubles for a few days already with handling form that contains dropdown list. I tried all that I've learned so far but nothing helps. This is my code: using System; using System.Collections.Generic; using System.Linq; using System.Web; using CMS; using CMS.Model; using System.ComponentModel.DataAnnotations; namespace Portal.Models { public class ArticleDisplay { public ArticleDisplay() { } public int CategoryID { set; get; } public string CategoryTitle { set; get; } public int ArticleID { set; get; } public string ArticleTitle { set; get; } public DateTime ArticleDate; public string ArticleContent { set; get; } } public class HomePageViewModel { public HomePageViewModel(IEnumerable<ArticleDisplay> summaries, Article article) { this.ArticleSummaries = summaries; this.NewArticle = article; } public IEnumerable<ArticleDisplay> ArticleSummaries { get; private set; } public Article NewArticle { get; private set; } } public class ArticleRepository { private DB db = new DB(); // // Query Methods public IQueryable<ArticleDisplay> FindAllArticles() { var result = from category in db.ArticleCategories join article in db.Articles on category.CategoryID equals article.CategoryID orderby article.Date descending select new ArticleDisplay { CategoryID = category.CategoryID, CategoryTitle = category.Title, ArticleID = article.ArticleID, ArticleTitle = article.Title, ArticleDate = article.Date, ArticleContent = article.Content }; return result; } public IQueryable<ArticleDisplay> FindTodayArticles() { var result = from category in db.ArticleCategories join article in db.Articles on category.CategoryID equals article.CategoryID where article.Date == DateTime.Today select new ArticleDisplay { CategoryID = category.CategoryID, CategoryTitle = category.Title, ArticleID = article.ArticleID, ArticleTitle = article.Title, ArticleDate = article.Date, ArticleContent = article.Content }; return result; } public Article GetArticle(int id) { return db.Articles.SingleOrDefault(d => d.ArticleID == id); } public IQueryable<ArticleDisplay> DetailsArticle(int id) { var result = from category in db.ArticleCategories join article in db.Articles on category.CategoryID equals article.CategoryID where id == article.ArticleID select new ArticleDisplay { CategoryID = category.CategoryID, CategoryTitle = category.Title, ArticleID = article.ArticleID, ArticleTitle = article.Title, ArticleDate = article.Date, ArticleContent = article.Content }; return result; } // // Insert/Delete Methods public void Add(Article article) { db.Articles.InsertOnSubmit(article); } public void Delete(Article article) { db.Articles.DeleteOnSubmit(article); } // // Persistence public void Save() { db.SubmitChanges(); } } } using System; using System.Collections.Generic; using System.Linq; using System.Web; using System.Web.Mvc; using Portal.Models; using CMS.Model; namespace Portal.Areas.CMS.Controllers { public class ArticleController : Controller { ArticleRepository articleRepository = new ArticleRepository(); ArticleCategoryRepository articleCategoryRepository = new ArticleCategoryRepository(); // // GET: /Article/ public ActionResult Index() { ViewData["categories"] = new SelectList ( articleCategoryRepository.FindAllCategories().ToList(), "CategoryId", "Title" ); Article article = new Article() { Date = DateTime.Now, CategoryID = 1 }; HomePageViewModel homeData = new HomePageViewModel(articleRepository.FindAllArticles().ToList(), article); return View(homeData); } // // GET: /Article/Details/5 public ActionResult Details(int id) { var article = articleRepository.DetailsArticle(id).Single(); if (article == null) return View("NotFound"); return View(article); } // // GET: /Article/Create //public ActionResult Create() //{ // ViewData["categories"] = new SelectList // ( // articleCategoryRepository.FindAllCategories().ToList(), "CategoryId", "Title" // ); // Article article = new Article() // { // Date = DateTime.Now, // CategoryID = 1 // }; // return View(article); //} // // POST: /Article/Create [ValidateInput(false)] [AcceptVerbs(HttpVerbs.Post)] public ActionResult Create(Article article) { if (ModelState.IsValid) { try { // TODO: Add insert logic here articleRepository.Add(article); articleRepository.Save(); return RedirectToAction("Index"); } catch { return View(article); } } else { return View(article); } } // // GET: /Article/Edit/5 public ActionResult Edit(int id) { ViewData["categories"] = new SelectList ( articleCategoryRepository.FindAllCategories().ToList(), "CategoryId", "Title" ); var article = articleRepository.GetArticle(id); return View(article); } // // POST: /Article/Edit/5 [ValidateInput(false)] [AcceptVerbs(HttpVerbs.Post)] public ActionResult Edit(int id, FormCollection collection) { Article article = articleRepository.GetArticle(id); try { // TODO: Add update logic here UpdateModel(article, collection.ToValueProvider()); articleRepository.Save(); return RedirectToAction("Details", new { id = article.ArticleID }); } catch { return View(article); } } // // HTTP GET: /Article/Delete/1 public ActionResult Delete(int id) { Article article = articleRepository.GetArticle(id); if (article == null) return View("NotFound"); else return View(article); } // // HTTP POST: /Article/Delete/1 [AcceptVerbs(HttpVerbs.Post)] public ActionResult Delete(int id, string confirmButton) { Article article = articleRepository.GetArticle(id); if (article == null) return View("NotFound"); articleRepository.Delete(article); articleRepository.Save(); return View("Deleted"); } [ValidateInput(false)] public ActionResult UpdateSettings(int id, string value, string field) { // This highly-specific example is from the original coder's blog system, // but you can substitute your own code here. I assume you can pick out // which text field it is from the id. Article article = articleRepository.GetArticle(id); if (article == null) return Content("Error"); if (field == "Title") { article.Title = value; UpdateModel(article, new[] { "Title" }); articleRepository.Save(); } if (field == "Content") { article.Content = value; UpdateModel(article, new[] { "Content" }); articleRepository.Save(); } if (field == "Date") { article.Date = Convert.ToDateTime(value); UpdateModel(article, new[] { "Date" }); articleRepository.Save(); } return Content(value); } } } and view: <%@ Page Title="" Language="C#" MasterPageFile="~/Areas/CMS/Views/Shared/Site.Master" Inherits="System.Web.Mvc.ViewPage<Portal.Models.HomePageViewModel>" %> <asp:Content ID="Content1" ContentPlaceHolderID="TitleContent" runat="server"> Index </asp:Content> <asp:Content ID="Content2" ContentPlaceHolderID="MainContent" runat="server"> <div class="naslov_poglavlja_main">Articles Administration</div> <%= Html.ValidationSummary("Create was unsuccessful. Please correct the errors and try again.") %> <% using (Html.BeginForm("Create","Article")) {%> <div class="news_forma"> <label for="Title" class="news">Title:</label> <%= Html.TextBox("Title", "", new { @class = "news" })%> <%= Html.ValidationMessage("Title", "*") %> <label for="Content" class="news">Content:</label> <div class="textarea_okvir"> <%= Html.TextArea("Content", "", new { @class = "news" })%> <%= Html.ValidationMessage("Content", "*")%> </div> <label for="CategoryID" class="news">Category:</label> <%= Html.DropDownList("CategoryId", (IEnumerable<SelectListItem>)ViewData["categories"], new { @class = "news" })%> <p> <input type="submit" value="Publish" class="form_submit" /> </p> </div> <% } %> <div class="naslov_poglavlja_main"><%= Html.ActionLink("Write new article...", "Create") %></div> <div id="articles"> <% foreach (var item in Model.ArticleSummaries) { %> <div> <div class="naslov_vijesti" id="<%= item.ArticleID %>"><%= Html.Encode(item.ArticleTitle) %></div> <div class="okvir_vijesti"> <div class="sadrzaj_vijesti" id="<%= item.ArticleID %>"><%= item.ArticleContent %></div> <div class="datum_vijesti" id="<%= item.ArticleID %>"><%= Html.Encode(String.Format("{0:g}", item.ArticleDate)) %></div> <a class="news_delete" href="#" id="<%= item.ArticleID %>">Delete</a> </div> <div class="dno"></div> </div> <% } %> </div> </asp:Content> When trying to post new article I get following error: System.InvalidOperationException: The ViewData item that has the key 'CategoryId' is of type 'System.Int32' but must be of type 'IEnumerable'. I really don't know what to do cause I'm pretty new to .net and mvc Any help appreciated! Ile EDIT: I found where I made mistake. I didn't include date. If in view form I add this line I'm able to add article: <%=Html.Hidden("Date", String.Format("{0:g}", Model.NewArticle.Date)) %> But, if I enter wrong datetype or leave title and content empty then I get the same error. In this eample there is no need for date edit, but I will need it for some other forms and validation will be necessary. EDIT 2: Error happens when posting! Call stack: App_Web_of9beco9.dll!ASP.areas_cms_views_article_create_aspx.__RenderContent2(System.Web.UI.HtmlTextWriter __w = {System.Web.UI.HtmlTextWriter}, System.Web.UI.Control parameterContainer = {System.Web.UI.WebControls.ContentPlaceHolder}) Line 31 + 0x9f bytes C#

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  • Determine size of SizeToContent WPF Window before its rendered

    - by DudeFX
    I have a window in my WPF application that is displayed on occasion. When it is shown it is faded in with an annimation, and when closed it is faded out. Nothing fancy, just a storyboard that modifies the opacity. Actually the window is never really closed, the opacity is just faded out to 0 where it remains until its to be displayed again. This window is an informative window and doesn't always show the same content. It is sized to content (Width and Height) and works well in that regard. The user chooses the basic area of the screen for it to be displayed (TopLeft, TopRight, Center, BottomLeft, BottomRight). Before the window is faded in the content is updated. Because the window is sized to content it increases or descreases in size. The width and height can change. When positioning the window, lets say, in the bottom right corner, I simply take the WorkingArea of the screen (width and height) and then minus the width/height of the window to get the Top and Left position that I need. The logic works, but the trouble I am having is the Window's Height and Width is not returning the size it is after the content was updated, but is returning the size it was the last time it was displayed. I am assuming this is because it hasn't yet been rendered with the new content. This causes me grief becuase if the Window is larger than it was the last time it obviously extends off the screen. I tried positioning the window in the OnContentRendered event, but this only fires once when the Window is created, not after the content has been updated, when the opacity is set to 0. Does anyone have any idea how I might get an accurate width and height of this window before it is faded in? Any help would be appreciated!!

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  • Rebinding events in jQuery after Ajax update (updatepanel)

    - by Hojou
    I have several input and option elements on my page, each (well almost) have an event attached to update some text on the page once they change. I use jQuery which is really really cool :) I also use Microsofts Ajax framework, utilizing the UpdatePanel. The reason why I do that is that certain elements are created on the page based on some server-side logic. I don't really want to explain why I use the UpdatePanel - even if it could (it can with quite some effort) be rewritten to use only jQuery I still want that UpdatePanel. You probably guessed it - once I have a postback on the UpdatePanel the jQuery events stops working. I actually was expecting this, since the "postback" is not really a new postback so my code in document.ready that binds the events won't be fired again. I also confirmed my suspicion by reading up on it in the jQuery help libraries. Anyway I'm left with the problem of rebinding my controls after the UpdatePanel is done updating the DOM. I preferably need a solution that does not require adding more .js files (jQuery plug-ins) to the page but something as simple as being able to catch the UpdatePanel's 'afterupdating' where I can just call my method to rebind all the form elements.

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  • Exception converting Office files to PDF using ABCpdf.NET onWindows Server 2008

    - by drivendevelopment
    Has anyone delt with this exception from ABCpdf? We're running on Server 2008 and only have issues converting Office files (Word and Excel). This all worked well on Server 2003. Because we're only having issues with Office files I wonder if it's related to the XPS support on Server 2008? The code that calls into this function is running as a Windows Service. Private Overloads Function ConvertMicrosoftOfficeDocToPdf(ByVal inputFile As Byte(), ByVal fileExt As String) As Byte() Dim abcDoc As WebSupergoo.ABCpdf7.Doc = Nothing Try abcDoc = New WebSupergoo.ABCpdf7.Doc() Dim xro As New WebSupergoo.ABCpdf7.XReadOptions() xro.FileExtension = fileExt Try abcDoc.Read(inputFile, xro) Catch ex As Exception System.Diagnostics.Trace.Write(ex.ToString()) Throw ex End Try Dim fileBytes As Byte() = abcDoc.GetData() Return fileBytes Finally If Not abcDoc Is Nothing Then abcDoc.Clear() abcDoc.Dispose() End If End Try End Function WebSupergoo.ABCpdf7.Internal.PDFException: Attempted to read or write protected memory. This is often an indication that other memory is corrupt. --- System.AccessViolationException: Attempted to read or write protected memory. This is often an indication that other memory is corrupt. at WebSupergoo.ABCpdf7.Internal.NDoc._InvokeMethod(IntPtr inDoc, Int32 inMethod, Int32 inIndex, Int32 inFlags, String inParams, String& outErr) at WebSupergoo.ABCpdf7.Internal.NDoc.InvokeMethod(IntPtr inDoc, Int32 inMethod, Int32 inIndex, Int32 inFlags, String inParams, String& outErr) at WebSupergoo.ABCpdf7.Doc.PrintToXps(String inputFile, String outputFile, Int32 timeout, String printerName) at WebSupergoo.ABCpdf7.Operations.XpsImportOperation.ImportAny(Doc doc, String path, Int32 timeout) at WebSupergoo.ABCpdf7.XReadOptions.ImportXpsAny(Doc doc, String path, Boolean clear) at WebSupergoo.ABCpdf7.XReadOptions.Read(Doc doc, Byte[] data, ReadModuleType module) at WebSupergoo.ABCpdf7.XReadOptions.Read(Doc doc, Byte[] data)

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  • Refresh UltraGrid's GroupBy Sort on child bands when ListChanged?

    - by Idriss
    I am using Infragistics 2009 vol 1. My UltraGrid is bound to a BindingList of business objects "A" having themself a BindingList property of business objects "B". It results in having two bands: one named "BindingList`1", the other one "ListOfB" thanks to the currency manager. I would like to refresh the GroupBy sort of the grid whenever a change is performed on the child band through the child business object and INotifyPropertyChange. If I group by a property in the child band which is a boolean (let's say "Active") and I subscribe to the event ListChanged on the bindinglist datasource with this event handler: void Grid_ListChanged(object sender, ListChangedEventArgs e) { if (e.ListChangedType == ListChangedType.ItemChanged) { string columnKey = e.PropertyDescriptor.Name; if (e.PropertyDescriptor.PropertyType.Name == "BindingList`1") { ultraGrid.DisplayLayout.Bands[columnKey].SortedColumns.RefreshSort(true); } else { UltraGridBand band = ultraGrid.DisplayLayout.Bands[0]; UltraGridColumn gc = band.Columns[columnKey]; if (gc.IsGroupByColumn || gc.SortIndicator != SortIndicator.None) { band.SortedColumns.RefreshSort(true); } ColumnFilter cf = band.ColumnFilters[columnKey]; if (cf.FilterConditions.Count > 0) { ultraGrid.DisplayLayout.RefreshFilters(); } } } } the band.SortedColumns.RefreshSort(true) is called but It gives unpredictable results in the groupby area when the property Active is changed in the child band: if one object out of three actives becomes inactive it goes from: Active : True (3 items) To: Active : False (3 items) Instead of (which is the case when I drag the column back and forth to the group by area) Active : False (1 item) Active : True (2 items) Am I doing something wrong? Is there a way to restore the expanded state of the rows when performing a RefreshSort(true); ?

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  • winforms databinding best practices

    - by Kaiser Soze
    Demands / problems: I would like to bind multiple properties of an entity to controls in a form. Some of which are read only from time to time (according to business logic). When using an entity that implements INotifyPropertyChanged as the DataSource, every change notification refreshes all the controls bound to that data source (easy to verify - just bind two properties to two controls and invoke a change notification on one of them, you will see that both properties are hit and reevaluated). There should be user friendly error notifications (the entity implements IDataErrorInfo). (probably using ErrorProvider) Using the entity as the DataSource of the controls leads to performance issues and makes life harder when its time for a control to be read only. I thought of creating some kind of wrapper that holds the entity and a specific property so that each control would be bound to a different DataSource. Moreover, that wrapper could hold the ReadOnly indicator for that property so the control would be bound directly to that value. The wrapper could look like this: interface IPropertyWrapper : INotifyPropertyChanged, IDataErrorInfo { object Value { get; set; } bool IsReadOnly { get; } } But this means also a different ErrorProvider for each property (property wrapper) I feel like I'm trying to reinvent the wheel... What is the 'proper' way of handling complex binding demands like these? Thanks ahead.

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  • Managing Dependency Hell with WiX and C#

    - by Tom the Junglist
    We are on the eve of product launch, and at the last minute I am being bombarded with crash reports that appear to be related to our installer, which is a WiX3 project with separate outputs for x86 and x64 builds. These have been an ongoing problem that I always thought were fixed, only to find out that they were still lurking. The product itself is a collection of binaries that communicate with each other via .Net remoting, including a Windows Service and a small COM component that is loaded as an addon in another app. The service runs as SYSTEM, the COM piece runs in a low-rights context, while the other pieces run in normal user contexts. Other pieces include an third-party COM object library DLL and a shared DLL with the .net Remoting interfaces. I've observed flat-out weird behavior with MSI, particularly on version upgrades. Between MS' anal strong-name implementation (specifically, the exact version check before loading a given assembly), a documented WiX/MSI bug that sees critical files erased on upgrades (essentially, if a file in the upgrade MSI has the same version number as the existing install, that file is deleted), and having to work around Wow64 virtualization (x86 MSI can only write to registry/HD locations via Wow64, yet x64 MSIs cannot run on x86 computers...), I am about ready to trash the whole thing and port it over to a different install system. What I am looking for on tips + tricks, techniques, or suggestions on how to properly do things so that I am not fighting with Windows Installer's twisted sense of logic. I am tired of fighting with WiX/MSI/Windows Installer. All it needs to do is place files and registry keys where I tell it to, upgrade them when appropriate, and don't delete anything until the user uninstalls. Instead, dependencies are deleted willy-nilly, bringing up a whole bunch of uncatchable exceptions (can't wrap a try{} block around function declarations) and GPF'ing the whole app. I am particularly interested in 'best practices' and examples regarding shared and dependency DLLs, and any tips on making sure if a file needs to go to GAC, that it actually goes to the GAC and stays there until it is appropriate to remove it. Thanks! Tom

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  • MVC - Cocoa interface - Cocoa Design pattern book

    - by Idan
    So I started reading this book: http://www.amazon.com/Cocoa-Design-Patterns-Erik-Buck/dp/0321535022 On chapter 2 it explains about the MVC design pattern and gives and example which I need some clarification to. The simple example shows a view with the following fields: hourlyRate, WorkHours, Standarthours , salary. The example is devided into 3 parts : View - contains some text fiels and a table (the table contains a list of employees' data). Controller - comprised of NSArrayController class (contains an array of MyEmployee) Model - MyEmployee class which describes an employee. MyEmployee class has one method which return the salary according to the calculation logic, and attributes in accordance with the view UI controls. MyEmployee inherits from NSManagedObject. Few things i'm not sure of : 1. Inside the MyEmplpyee class implemenation file, the calculation method gets the class attributes using sentence like " [[self valueForKey:@"hourlyRate"] floatValue];" Howevern, inside the header there is no data member named hourlyRate or any of the view fields. I'm not quite sure how does it work, and how it gets the value from the right view field. (does it have to be the same name as the field name in the view). maybe the conncetion is made somehow using the Interface builder and was not shown in the book ? and more important: 2. how does it seperate the view from the model ? let's say ,as the book implies might happen, I decide one day to remove one of the fields in the view. as far as I understand, that means changing the way the salary method works in MyEmplpyee (cause we have one field less) , and removing one attribute from the same calss. So how is that separate the View from the Model if changing one reflect on the other ? I guess I get something wrong... Any comments ? Thanks

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