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• What is the worst gotcha in WPF?

  - by David

  Hi, I've started to make myself a list of "WPF gotchas": things that bug me and that I had to write down to remember because I fall for them every time.... Now, I'm pretty sure you all stumbled upon similar situations at one point, and I would like you to share your experience on the subject: What is the gotcha that gets you all the time? the one you find the most annoying? (I have a few issues that seem to be without explanation, maybe your submissions will explain them) Here are a few of my "personnal" gotchas (randomly presented): For a MouseEvent to be fired even when the click is on the "transparent" background of a control (e.g. a label) and not just on the content (the Text in this case), the control's Background has to be set to "Brushes.Transparent" and not just "null" (default value for a label) A WPF DataGridCell's DataContext is the RowView to whom the cell belong, not the CellView When inside a ScrollViewer, a Scrollbar is managed by the scrollviewer itself (i.e. setting properties such as ScrollBar.Value is without effect) Key.F10 is not fired when you press "F10", instead you get Key.System and you have to go look for e.SystemKey to get the Key.F10 ... and now you're on.

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• JAXM soap message parsing

  - by Dean

  I am getting the following XML back from a .net service: <?xml version="1.0" encoding="utf-8"?> <soap:Envelope xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema"> <soap:Body> <validateCredentialsResponse xmlns="http://www.paragon.com/positionmonitor/PositionMonitor"> <validateCredentialsResult> <ResultData xsi:type="ValidateCredentialsResultData"> <validated>true</validated> <alreadyLoggedIn>false</alreadyLoggedIn> </ResultData> <Status> <Condition xmlns="">SUCCESS</Condition> <ErrorCode xmlns="">BO.00000</ErrorCode> <ErrorDesc xmlns="">OK</ErrorDesc> </Status> </validateCredentialsResult> </validateCredentialsResponse> </soap:Body> </soap:Envelope> ...and I'm trying to parse it using JAXM, however the following always evaluates to null: SOAPEnvelope env = reply.getSOAPPart().getEnvelope(); Can anyone help me out here?

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• Why does mmap() fail with ENOMEM on a 1TB sparse file?

  - by metadaddy

  I've been working with large sparse files on openSUSE 11.2 x86_64. When I try to mmap() a 1TB sparse file, it fails with ENOMEM. I would have thought that the 64 bit address space would be adequate to map in a terabyte, but it seems not. Experimenting further, a 1GB file works fine, but a 2GB file (and anything bigger) fails. I'm guessing there might be a setting somewhere to tweak, but an extensive search turns up nothing. Here's some sample code that shows the problem - any clues? #include <errno.h> #include <fcntl.h> #include <stdio.h> #include <stdlib.h> #include <string.h> #include <sys/mman.h> #include <sys/types.h> #include <unistd.h> int main(int argc, char *argv[]) { char * filename = argv[1]; int fd; off_t size = 1UL << 40; // 30 == 1GB, 40 == 1TB fd = open(filename, O_RDWR | O_CREAT | O_TRUNC, 0666); ftruncate(fd, size); printf("Created %ld byte sparse file\n", size); char * buffer = (char *)mmap(NULL, (size_t)size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0); if ( buffer == MAP_FAILED ) { perror("mmap"); exit(1); } printf("Done mmap - returned 0x0%lx\n", (unsigned long)buffer); strcpy( buffer, "cafebabe" ); printf("Wrote to start\n"); strcpy( buffer + (size - 9), "deadbeef" ); printf("Wrote to end\n"); if ( munmap(buffer, (size_t)size) < 0 ) { perror("munmap"); exit(1); } close(fd); return 0; }

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• Updating a C# 2.0 events example to be idiomatic with C# 3.5?

  - by Damien Wildfire

  I have a short events example from .NET 2.0 that I've been using as a reference point for a while. We're now upgrading to 3.5, though, and I'm not clear on the most idiomatic way to do things. How would this simple events example get updated to reflect idioms that are now available in .NET 3.5? // Args class. public class TickArgs : EventArgs { private DateTime TimeNow; public DateTime Time { set { TimeNow = value; } get { return this.TimeNow; } } } // Producer class that generates events. public class Metronome { public event TickHandler Tick; public delegate void TickHandler(Metronome m, TickArgs e); public void Start() { while (true) { System.Threading.Thread.Sleep(3000); if (Tick != null) { TickArgs t = new TickArgs(); t.Time = DateTime.Now; Tick(this, t); } } } } // Consumer class that listens for events. public class Listener { public void Subscribe(Metronome m) { m.Tick += new Metronome.TickHandler(HeardIt); } private void HeardIt(Metronome m, TickArgs e) { System.Console.WriteLine("HEARD IT AT {0}",e.Time); } } // Example. public class Test { static void Main() { Metronome m = new Metronome(); Listener l = new Listener(); l.Subscribe(m); m.Start(); } }

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• How can i initialise a server on startup?

  - by djerry

  Hey all, I need to make some connections on startup of a server. I'm using the wcf technology for this client-server application. The problem is that the constructor of the server isn't called at any time, so for the moment, i initialize the connections when the first client makes a connection. But this generates problems in a further part. This is my server setup: private static ServiceHost _svc; static void Main(string[] args) { NetTcpBinding binding = new NetTcpBinding(SecurityMode.Message); Uri address = new Uri("net.tcp://localhost:8000"); _svc = new ServiceHost(typeof(MonitoringSystemService), address); publishMetaData(_svc, "http://localhost:8001"); _svc.AddServiceEndpoint(typeof(IMonitoringSystemService), binding, "Monitoring Server"); _svc.Open(); Console.WriteLine("Listener service gestart op net.tcp://localhost:8000/Monitoring"); Console.ReadLine(); } private static void publishMetaData(ServiceHost svc, string sEndpointAddress) { ServiceMetadataBehavior smb = svc.Description.Behaviors.Find<ServiceMetadataBehavior>(); if (smb != null) { smb.HttpGetEnabled = true; smb.HttpGetUrl = new Uri(sEndpointAddress); } else { smb = new ServiceMetadataBehavior(); smb.HttpGetEnabled = true; smb.HttpGetUrl = new Uri(sEndpointAddress); svc.Description.Behaviors.Add(smb); } } How can i start the server without waiting for a client to logon so i can initialize it. Thanks in advance.

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• Can you explain this generics behavior and if I have a workaround?

  - by insta

  Sample program below: using System; using System.Collections.Generic; using System.Linq; using System.Text; namespace GenericsTest { class Program { static void Main(string[] args) { IRetrievable<int, User> repo = new FakeRepository(); Console.WriteLine(repo.Retrieve(35)); } } class User { public int Id { get; set; } public string Name { get; set; } } class FakeRepository : BaseRepository<User>, ICreatable<User>, IDeletable<User>, IRetrievable<int, User> { // why do I have to implement this here, instead of letting the // TKey generics implementation in the baseclass handle it? //public User Retrieve(int input) //{ // throw new NotImplementedException(); //} } class BaseRepository<TPoco> where TPoco : class,new() { public virtual TPoco Create() { return new TPoco(); } public virtual bool Delete(TPoco item) { return true; } public virtual TPoco Retrieve<TKey>(TKey input) { return null; } } interface ICreatable<TPoco> { TPoco Create(); } interface IDeletable<TPoco> { bool Delete(TPoco item); } interface IRetrievable<TKey, TPoco> { TPoco Retrieve(TKey input); } } This sample program represents the interfaces my actual program uses, and demonstrates the problem I'm having (commented out in FakeRepository). I would like for this method call to be generically handled by the base class (which in my real example is able to handle 95% of the cases given to it), allowing for overrides in the child classes by specifying the type of TKey explicitly. It doesn't seem to matter what parameter constraints I use for the IRetrievable, I can never get the method call to fall through to the base class. Also, if anyone can see an alternate way to implement this kind of behavior and get the result I'm ultimately looking for, I would be very interested to see it. Thoughts?

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• Effective optimization strategies on modern C++ compilers

  - by user168715

  I'm working on scientific code that is very performance-critical. An initial version of the code has been written and tested, and now, with profiler in hand, it's time to start shaving cycles from the hot spots. It's well-known that some optimizations, e.g. loop unrolling, are handled these days much more effectively by the compiler than by a programmer meddling by hand. Which techniques are still worthwhile? Obviously, I'll run everything I try through a profiler, but if there's conventional wisdom as to what tends to work and what doesn't, it would save me significant time. I know that optimization is very compiler- and architecture- dependent. I'm using Intel's C++ compiler targeting the Core 2 Duo, but I'm also interested in what works well for gcc, or for "any modern compiler." Here are some concrete ideas I'm considering: Is there any benefit to replacing STL containers/algorithms with hand-rolled ones? In particular, my program includes a very large priority queue (currently a std::priority_queue) whose manipulation is taking a lot of total time. Is this something worth looking into, or is the STL implementation already likely the fastest possible? Along similar lines, for std::vectors whose needed sizes are unknown but have a reasonably small upper bound, is it profitable to replace them with statically-allocated arrays? I've found that dynamic memory allocation is often a severe bottleneck, and that eliminating it can lead to significant speedups. As a consequence I'm interesting in the performance tradeoffs of returning large temporary data structures by value vs. returning by pointer vs. passing the result in by reference. Is there a way to reliably determine whether or not the compiler will use RVO for a given method (assuming the caller doesn't need to modify the result, of course)? How cache-aware do compilers tend to be? For example, is it worth looking into reordering nested loops? Given the scientific nature of the program, floating-point numbers are used everywhere. A significant bottleneck in my code used to be conversions from floating point to integers: the compiler would emit code to save the current rounding mode, change it, perform the conversion, then restore the old rounding mode --- even though nothing in the program ever changed the rounding mode! Disabling this behavior significantly sped up my code. Are there any similar floating-point-related gotchas I should be aware of? One consequence of C++ being compiled and linked separately is that the compiler is unable to do what would seem to be very simple optimizations, such as move method calls like strlen() out of the termination conditions of loop. Are there any optimization like this one that I should look out for because they can't be done by the compiler and must be done by hand? On the flip side, are there any techniques I should avoid because they are likely to interfere with the compiler's ability to automatically optimize code? Lastly, to nip certain kinds of answers in the bud: I understand that optimization has a cost in terms of complexity, reliability, and maintainability. For this particular application, increased performance is worth these costs. I understand that the best optimizations are often to improve the high-level algorithms, and this has already been done.

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• JDBC with JSP fails to insert

  - by StrykeR

  I am having some issues right now with JDBC in JSP. I am trying to insert username/pass ext into my MySQL DB. I am not getting any error or exception, however nothing is being inserted into my DB either. Below is my code, any help would be greatly appreciated. <% String uname=request.getParameter("userName"); String pword=request.getParameter("passWord"); String fname=request.getParameter("firstName"); String lname=request.getParameter("lastName"); String email=request.getParameter("emailAddress"); %> <% try{ String dbURL = "jdbc:mysql:localhost:3306/assi1"; String user = "root"; String pwd = "password"; String driver = "com.mysql.jdbc.Driver"; String query = "USE Users"+"INSERT INTO User (UserName, UserPass, FirstName, LastName, EmailAddress) " + "VALUES ('"+uname+"','"+pword+"','"+fname+"','"+lname+"','"+email+"')"; Class.forName(driver); Connection conn = DriverManager.getConnection(dbURL, user, pwd); Statement statement = conn.createStatement(); statement.executeUpdate(query); out.println("Data is successfully inserted!"); } catch(SQLException e){ for (Throwable t : e) t.printStackTrace(); } %> DB script here: CREATE DATABASE Users; use Users; CREATE TABLE User ( UserID INT NOT NULL AUTO_INCREMENT, UserName VARCHAR(20), UserPass VARCHAR(20), FirstName VARCHAR(30), LastName VARCHAR(35), EmailAddress VARCHAR(50), PRIMARY KEY (UserID) );

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• How to defer execution of an Event on each item in a collection until iteration of collection is com

  - by Metro Smurf

  Of Note: This is more of a curiosity question than anything else. Given a List<Window> where each window has an event attached to the Close Event which removes the window from the collection, how could you use delegates / events to defer the execution of the Close Event until the collection has been iterated? For example: public class Foo { private List<Window> OpenedWindows { get; set; } public Foo() { OpenedWindows = new List<Window>(); } public void AddWindow( Window win ) { win.Closed += OnWindowClosed; OpenedWindows.Add( win ); } void OnWindowClosed( object sender, EventArgs e ) { var win = sender as Window; if( win != null ) { OpenedWindows.Remove( win ); } } void CloseAllWindows() { // obviously will not work because we can't // remove items as we iterate the collection // (the close event removes the window from the collection) OpenedWindows.ForEach( x => x.Close() ); // works fine, but would like to know how to do // this with delegates / events. while( OpenedWindows.Any() ) { OpenedWindows[0].Close(); } } } Specifically, within the CloseAllWindows() method, how could you iterate the collection to call the close event, but defer the event being raised until the collection has been completely iterated?

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• PHP 5.3 and interface \ArrayAccess

  - by Jakub Lédl

  I'm now working on a project and I have one class that implements the ArrayAccess interface. Howewer, I'm getting an error that says that my implementation: must be compatible with that of ArrayAccess::offsetSet(). My implementation looks like this: public function offsetSet($offset, $value) { if (!is_string($offset)) { throw new \LogicException("..."); } $this->params[$offset] = $value; } So, to me it looks like my implementation is correct. Any idea what is wrong? Thanks very much! The class look like this: class HttpRequest implements \ArrayAccess { // tons of private variables, methods for working // with current http request etc. Really nothing that // could interfere with that interface. // ArrayAccess implementation public function offsetExists($offset) { return isset ($this->params[$offset]); } public function offsetGet($offset) { return isset ($this->params[$offset]) ? $this->params[$offset] : NULL; } public function offsetSet($offset, $value) { if (!is_string($offset)) { throw new \LogicException("You can only assing to params using specified key."); } $this->params[$offset] = $value; } public function offsetUnset($offset) { unset ($this->params[$offset]); } }

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• How to convert object to string list?

  - by user1381501

  I want to get two values by using linq select query and try to convert object to string list. I am trying to convert list to list. The code as below. I got the error when I convert object to string list : return returnvalue = (List)userlist; public List<string> GetUserList(string username) { List<User> UserList = new List<User>(); List<string> returnvalue=new List<string>(); try { string returnstring = string.Empty; DataTable dt = null; dt = Library.Helper.FindUser(username, 200); foreach (DataRow dr in dt.Rows) { User user = new User(); spuser.id = dr["ID"].ToString(); spuser.name = dr["Name"].ToString(); UserList.Adduser } } catch (Exception ex) { } List<SharePointMentoinUser> userlist = UserList.Select(a => new User { name = (string)a.name, id = (string)a.id }).ToList(); **return returnvalue = (List<string>)userlist;** }

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• Using parameterized function calls in SELECT statements. MS SQL Server

  - by geekzlla

  I have taken over some code from a previous developer and have come across this SQL statement that calls several SQL functions. As you can see, the function calls in the select statement pass a parameter to the function. How does the SQL statement know what value to replace the variable with? For the below sample, how does the query engine know what to replace nDeptID with when it calls, fn_SelDeptName_DeptID(nDeptID)? nDeptID IS a column in table Note. SELECT STATEMENT: SELECT nCustomerID AS [Customer ID], nJobID AS [Job ID], dbo.fn_SelDeptName_DeptID(nDeptID) AS Department, nJobTaskID AS JobTaskID, dbo.fn_SelDeptTaskDesc_OpenTask(nJobID, nJobTaskID) AS Task, nStandardNoteID AS StandardNoteID, dbo.fn_SelNoteTypeDesc(nNoteID) AS [Note Type], dbo.fn_SelGPAStandardNote(nStandardNoteID) AS [Standard Note], nEntryDate AS [Entry Date], nUserName as [Added By], nType AS Type, nNote AS Note FROM Note WHERE nJobID = 844261 xORDER BY nJobID, Task, [Entry Date] ====================== Function fn_SelDeptName_DeptID: ALTER FUNCTION [dbo].[fn_SelDeptName_DeptID] (@iDeptID int) RETURNS varchar(25) -- Used by DataCollection for Job Tracking -- if the Deptartment isnt found return an empty string BEGIN -- Return the Department name for the given DeptID. DECLARE @strDeptName varchar(25) IF @iDeptID = 0 SET @strDeptName = '' ELSE BEGIN SET @strDeptName = (SELECT dName FROM Department WHERE dDeptID = @iDeptID) IF (@strDeptName IS NULL) SET @strDeptName = '' END RETURN @strDeptName END ========================== Thanks in advance.

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• Google Sites API - File Cabinets: Spaces and extension separator (.) are removed from file names

  - by user1299447

  We have a series of internal reports that we update regularly from our internal databases. We built an application in C# that uploads these reports to a Google Site. Everything works fine, except that the name of the file shown to the final user in the File Cabinet does not include the original spaces nor the extension separator (.) For example, Stock per warehouse.pdf is shown as : Stockperwarehousepdf Below is a simplified version of the code. private AtomEntry UploadAttachment(string filename, AtomEntry parent, string title, string description) { SiteEntry entry = new SiteEntry(); AtomCategory category = new AtomCategory(SitesService.ATTACHMENT_TERM, SitesService.KIND_SCHEME); category.Label = "attachment"; entry.Categories.Add(category); AtomLink parentLink = new AtomLink(AtomLink.ATOM_TYPE, SitesService.PARENT_REL); parentLink.HRef = parent.SelfUri; entry.Links.Add(parentLink); entry.MediaSource = new MediaFileSource(filename, MediaFileSource.GetContentTypeForFileName(filename)); entry.Content.Type = MediaFileSource.GetContentTypeForFileName(filename); entry.Title.Text= title; entry.Summary.Text = description; AtomEntry newEntry = null; newEntry = service.Insert(new Uri(makeFeedUri("content")), entry); } The key line is where the MediaFileSource object is created. Any idea of what we are missing? I've tried all sort of changes :(

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• In Safari, using jQuery a Form Input Text Field does not receive focus after alert is displayed. Why

  - by Rob

  I have an ASPX web form. I use jQuery to simply my Javascript. I use a Javascript validation script to validate each of the form fields' values. If an error occurs, I popup an alert with an error message. Then I transfer focus to the underlying element. Here are examples I have tried. Using jQuery: var Form_FieldDef = function(name) { this.name = name; this.SetFocus = function() { $('#' + this.name)[0].focus(); } this.Validate = function() { var isvalid = true; if ( $.trim($('#' + this.name).val()) == '') { alert("Your entry is empty"); this.SetFocus(); isvalid = false; } return isvalid; } } This works on IE7, IE8, Opera, Chrome, and Firefox. It does not work on Safari 4 on PC. I don't have a Mac. So I changed the SetFocus method to this. this.SetFocus = function() { var fld = document.getElementById(this.name); if (fld != null) fld.focus(); } This works on IE7, IE8, Opera, Chrome, and Firefox. It does not work on Safari 4 on PC. I stepped through the code with VS 2008 debugger, and I'm calling the focus method on the underlying element.

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• Change clickable TextView's color on focus and click?

  - by Daniel Jonsson

  I have a clickable TextView that I want to give some colors to. But I don't know how. Here are the relevant code snippets from my two files that I'm working with: TextView title = new TextView(this); title.setLayoutParams(new LayoutParams(LayoutParams.FILL_PARENT, LayoutParams.WRAP_CONTENT)); title.setTextColor(R.color.textcolor); title.setText(titleLine); title.setTypeface(null, Typeface.BOLD); title.setClickable(true); title.setId(idLine); title.setFocusable(true); title.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View v) { /* Irrelevant code */ } }); And this is my textcolor.xml file: <?xml version="1.0" encoding="utf-8"?> <selector xmlns:android="http://schemas.android.com/apk/res/android"> <item android:state_pressed="true" android:color="#000000"/> <!-- pressed --> <item android:state_focused="true" android:color="#000000"/> <!-- focused --> <item android:color="#000000"/> <!-- default --> </selector> When I use the textcolor-file by typing title.setTextColor(R.color.textcolor);, the textcolor just becomes grey, regardless if I press it or so. Which is strange since I have written "#000000" in all color fields. But if I remove the setTextColor code, gets the textView a light grey color, and when I press it, it becomes black. But that aren't the colors that I want. So, can anyone help me with this problem? Just to clarify: I want to be able to specify the colors for the text when it's normal, pressed and focused.

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• Launching and Intent from file and mime type

  - by stonedonkey

  I've reviewed all the similar questions here, but I can't for the life of me figure out what I'm doing wrong. I've written an application that tries to launch various files, sort of a file browser, when a file is clicked it tries to launch the program based on it's associated MIME type or I want it to present the "Choose Application to Launch" dialog. Here's the code I'm using to launch: File file = new File(app.mediaPath() + "/" +_mediaFiles.get(position)); Intent myIntent = new Intent(android.content.Intent.ACTION_VIEW); String extension = android.webkit.MimeTypeMap.getFileExtensionFromUrl(Uri.fromFile(file).toString()); String mimetype = android.webkit.MimeTypeMap.getSingleton().getMimeTypeFromExtension(extension); myIntent.setDataAndType(Uri.fromFile(file),mimetype); startActivity(myIntent); This fails and generates a: android.content.ActivityNotFoundException: No Activity found to handle Intent { act=android.intent.action.VIEW dat=file:///file:/mnt/sdcard/roms/nes/Baseball_simulator.nes } Now if I install OI File Manager for instance, it opens instead of this error being thrown, and then if I click the same file from within in it, it launches the approriate dialogs. I have noticed that the MIME type for that particular file fails, but other mime types like .zip do return values. Am I missing something that when the MIME type is null to call a dialog that lets the user select? I've tried other variations of launching the app, including not setting the mime type and only using .setData with no success. The action I want to happen is, a user clicks a file, if it's associated with an application that app launches, if not, the user gets the "Complete action using" dialog with a list of apps. Thanks for any advice.

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• How to use App.Xaml's ResourseDictionaries with own entry point

  - by Polaris

  Hello friends. I created some logic for singleInstance application and I must to use my own entry point (not App.xaml) for Application. I have some styles in App.xaml which now is not working. How can I use this ResourceDictionaries from my App.xaml for entire project in my situation? My class for manage Application Startup public class SingleInstanceManager : WindowsFormsApplicationBase { App app; public SingleInstanceManager() { this.IsSingleInstance = true; } protected override bool OnStartup(Microsoft.VisualBasic.ApplicationServices.StartupEventArgs e) { try { // First time app is launched app = new App(); App.Current.Properties["rcID"] = e.CommandLine; //IntroLibrary.OpenDocumentFromNotify(); app.Run(); return false; } catch (Exception ex) { MessageBox.Show(ex.Message); return false; } } protected override void OnStartupNextInstance(StartupNextInstanceEventArgs eventArgs) { // Subsequent launches base.OnStartupNextInstance(eventArgs); Intro win = (Intro)app.MainWindow; if (eventArgs != null) { App.Current.Properties["rcID"] = eventArgs.CommandLine[0]; } IntroLibrary.OpenDocumentFromNotify(); app.Activate(); } } and my own Entry Point: public class EntryPoint { [STAThread] public static void Main(string[] args) { SingleInstanceManager manager = new SingleInstanceManager(); manager.Run(args); } } And my App.Xaml code behind: public partial class App : Application { protected override void OnStartup(System.Windows.StartupEventArgs e) { base.OnStartup(e); // Create and show the application's main window Intro window = new Intro(); window.Show(); } public void Activate() { // Reactivate application's main window this.MainWindow.Activate(); } } And my App.xaml has some code which decribe ResourceDictionaries which doesnt work. Why?

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• How good idea is it to use code contracts in Visual Studio 2010 Professional (ie. no static checking

  - by Lasse V. Karlsen

  I create class libraries, some which are used by others around the world, and now that I'm starting to use Visual Studio 2010 I'm wondering how good idea it is for me to switch to using code contracts, instead of regular old-style if-statements. ie. instead of this: if (String.IsNullOrWhiteSpace(fileName)) throw new ArgumentNullException("fileName"); (yes, I know, if it is whitespace, it isn't strictly null) use this: Contract.Requires(!String.IsNullOrWhiteSpace(fileName)); The reason I'm asking is that I know that the static checker is not available to me, so I'm a bit nervous about some assumptions that I make, that the compiler cannot verify. This might lead to the class library not compiling for someone that downloads it, when they have the static checker. This, coupled with the fact that I cannot even reproduce the problem, would make it tiresome to fix, and I would gather that it doesn't speak volumes to the quality of my class library if it seemingly doesn't even compile out of the box. So I have a few questions: Is the static checker on by default if you have access to it? Or is there a setting I need to switch on in the class library (and since I don't have the static checker, I won't) Are my fears unwarranted? Is the above scenario a real problem? Any advice would be welcome.

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• What is a good "Error Checking" Pattern (Java)?

  - by Jack

  I'll explain what I mean by input error checking. Say you have a function doSomething(x). If the function completes successfully doSomething does something and returns nothing. However, if there are errors I'd like to be notified. That is what I mean by error checking. I'm looking for, in general, the best way to check for errors. I've thought of the following solutions, each with a potential problem. Flag error checking. If doSomething(x) completes successfully return null. Otherwise, it returns a boolean or an error string. Problem: Side effects. Throwing an exception. Throw an exception if doSomething(x) encounters an error. Problem: If you are performing error checking for parameters only, throwing an IllegalArgumentExceptionseems inappropriate. Validating input prior to function call. If the error checking is only meant for the parameters of the function, then you can call a validator function before calling the doSomething(x) function. Problem: What if a client of the class forgets to call the validator function before calling doSomething(x)? I often encounter this problem and any help or a point in the right direction would be much appreciated.

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• Sha256 is giving junk output

  - by user1746617

  hey can u be more specific on how to convert to bin to hex. bool HashStatus::calculate_digest_value(char * path,unsigned char * output) { FILE* file = fopen(path, "rb"); if(!file) { g_message("SignatureValidator::VerifyReferences,file not opened"); return -1; } unsigned char hash[SHA256_DIGEST_LENGTH]; SHA256_CTX sha256; SHA256_Init(&sha256); const int bufSize = 32768; unsigned char* buffer = malloc(bufSize); int bytesRead = 0; if(!buffer) return NULL; while((bytesRead = fread(buffer, 1, bufSize, file))) { g_message("calculate digest value,verify.cpp::%s",buffer); SHA256_Update(&sha256, buffer, bytesRead); } SHA256_Final(hash, &sha256); g_message("verify.cpp,after final"); sha256_hash_string(hash, output); g_message("verify.cpp,after sha256_hash_string %s",hash); fclose(file); free(buffer); return true; } this is my code to convert file data into hash using sha256 openssl function o/p is :1d54e12333988471354907a760b9cde861423615bb5255ee837e3b27b32366 but actual o/p is:HVThAjM5iEcTVJB6dgC5zehhQjYVu1JV7oN+OyezI2Y= can you guys please help me with whatz wrong with this code,ASAP and i'm new to this please guide me step by step and in detail..

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• PHP classes, parse syntax errors when using 'var' to declare variables

  - by jon

  I am a C# guy trying to translate some of my OOP understanding over to php. I'm trying to make my first class object, and are hitting a few hitches. Here is the beginning of the class: <?php require("Database/UserDB.php"); class User { private var $uid; private var $username; private var $password; private var $realname; private var $email; private var $address; private var $phone; private var $projectArray; public function _construct($username) { $userArray = UserDB::GetUserArray($username); $uid = $userArray['uid']; $username = $userArray['username']; $realname = $userArray['realname']; $email = $userArray['email']; $phone = $userArray['phone']; $i = 1; $projectArray = UserDB::GetUserProjects($this->GetID()); while($projectArray[$i] != null) { $projectArray[$i] = new Project($projectArray[$i]); } UserDB.php is where I have all my static functions interacting with the Database for this User Class. I am getting errors using when I use var, and I'm getting confused. I know I don't HAVE to use var, or declare the variables at all, but I feel it is a better practice to do so. the error is "unexpected T_VAR, expecting T_VARIABLE" When I simply remove var from the declarations it works. Why is this?

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• Creating Thread in Win32

  - by Dave18

  Does ThreadFunc() gets called two times here? sometimes I notice a single call and sometimes none at all. #include <windows.h> #include <stdio.h> DWORD WINAPI ThreadFunc(LPVOID); int main() { HANDLE hThread; DWORD threadld; hThread = CreateThread(NULL, 0, ThreadFunc, 0, 0, &threadld ); printf("Thread is running\n"); } DWORD WINAPI ThreadFunc(LPVOID p) { printf("In ThreadFunc\n"); return 0; } Output 1 Thread is running In ThreadFunc In ThreadFunc Press any key to continue . . . Output 2 Thread is running In ThreadFunc Press any key to continue . . . Output 3 Thread is running Press any key to continue . . .

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• Check for existing mapping when writing a custom applier in ConfORM

  - by Philip Fourie

  I am writing my first custom column name applier for ConfORM. How do I check if another column has already been map with same mapping name? This is what I have so far: public class MyColumnNameApplier : IPatternApplier<PropertyPath, IPropertyMapper> { public bool Match(PropertyPath subject) { return (subject.LocalMember != null); } public void Apply(PropertyPath subject, IPropertyMapper applyTo) { string shortColumnName = ToOracleName(subject); // How do I check if the short columnName already exist? applyTo.Column(cm => cm.Name(shortColumnName)); } private string ToOracleName(PropertyPath subject) { ... } } } I need to shorten my class property names to less than 30 characters to fit in with Oracle's 30 character limit. Because I am shortening the column names it is possible that I generate the same name for two different properties. I would like to know when a duplicate mapping occurs. If I don't handle this scenario ConfORM/NHibernate allows two different properties to 'share' the same column name - this is obviously creates a problem for me.

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• Pthread - setting scheduler parameters

  - by Andna

  I wanted to use read-writer locks from pthread library in a way, that writers have priority over readers. I read in my man pages that If the Thread Execution Scheduling option is supported, and the threads involved in the lock are executing with the scheduling policies SCHED_FIFO or SCHED_RR, the calling thread shall not acquire the lock if a writer holds the lock or if writers of higher or equal priority are blocked on the lock; otherwise, the calling thread shall acquire the lock. so I wrote small function that sets up thread scheduling options. void thread_set_up(int _thread) { struct sched_param *_param=malloc(sizeof (struct sched_param)); int *c=malloc(sizeof(int)); *c=sched_get_priority_min(SCHED_FIFO)+1; _param->__sched_priority=*c; long *a=malloc(sizeof(long)); *a=syscall(SYS_gettid); int *b=malloc(sizeof(int)); *b=SCHED_FIFO; if (pthread_setschedparam(*a,*b,_param) == -1) { //depending on which thread calls this functions, few thing can happen if (_thread == MAIN_THREAD) client_cleanup(); else if (_thread==ACCEPT_THREAD) { pthread_kill(params.main_thread_id,SIGINT); pthread_exit(NULL); } } } sorry for those a,b,c but I tried to malloc everything, still I get SIGSEGV on the call to pthread_setschedparam, I am wondering why?

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• Python Webkit browser's inspector is missing a few things

  - by NoBugs

  I'm using a Webkit browser inspector like this. When I run it in Ubuntu 12.10, I'm getting errors when using the inspector. For example: ** Message: console message: file:///usr/share/webkitgtk-1.0/webinspector/UIString.js @42: Localized string "Go to line" not found. ** Message: console message: file:///usr/share/webkitgtk-1.0/webinspector/UIString.js @42: Localized string "Filter" not found. ** Message: console message: file:///usr/share/webkitgtk-1.0/webinspector/UIString.js @42: Localized string "Search Previous" not found. ** Message: console message: file:///usr/share/webkitgtk-1.0/webinspector/UIString.js @42: Localized string "Search Next" not found. ** Message: console message: file:///usr/share/webkitgtk-1.0/webinspector/UIString.js @42: Localized string "a:" not found. ** Message: console message: file:///usr/share/webkitgtk-1.0/webinspector/UIString.js @42: Localized string "%d of %d" not found. (geany:2487): Gdk-CRITICAL **: IA__gdk_error_trap_pop: assertion `gdk_error_traps != NULL' failed ** Message: console message: file:///usr/share/webkitgtk-1.0/webinspector/UIString.js @42: Localized string "Sources Panel" not found. ** Message: console message: file:///usr/share/webkitgtk-1.0/webinspector/UIString.js @42: Localized string "Toggle breakpoint" not found. ** Message: console message: file:///usr/share/webkitgtk-1.0/webinspector/UIString.js @42: Localized string "Painting" not found. I also noticed the breadcrumb/slider bar doesn't show when you have the console in the lower half: I don't remember this in earlier versions, and when I use the GTK3 version (from gi.repository import WebKit etc) it has similar problem, and is even worse, scrollbars don't have arrows at top and bottom. Am I missing a step on initializing the Webkit inspector or English locale for it? I would like to debug this issue, but since the inspector object isn't a webview object, I'm not sure I can add an inspector to the inspector? (like how you can use F12 when inspector is its own window in Chrome/Chromium, which lets you debug that inspector). It should be possible, but maybe not with pyGTK?

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