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  • Boost::Thread linking error on OSX?

    - by gct
    So I'm going nuts trying to figure this one out. Here's my basic setup: I'm compiling a shared library with a bunch of core functionality that uses a lot of boost stuff. We'll call this library libpf_core.so. It's linked with the boost static libraries, specifically the python, system, filesystem, thread, and program_options libraries. This all goes swimmingly. Now, I have a little test program called test_socketio which is compiled into a shared library (it's loaded as a plugin at runtime). It uses some boost stuff like boost::bind and boost::thread, and it's linked again libpf_core.so (which has the boost libraries included remember). When I go to compile test_socketio though, out of all my plugins it gives me a linking error: [ Building test_socketio ] g++ -c -pg -g -O0 -I/usr/local/include -I../include test_socketio.cc -o test_socketio.o g++ -shared test_socketio.o -lpy_core -o test_socketio.so Undefined symbols: "boost::lock_error::lock_error()", referenced from: boost::unique_lock<boost::mutex>::lock() in test_socketio.o ld: symbol(s) not found collect2: ld returned 1 exit status And I'm going crazy trying to figure out why this is. I've tried explicitly linking boost::thread into the plugin to no avail, tried ensuring that I'm using the boost headers associated with the libraries linked into libpf_core.so in case there was a conflict there. Is there something OSX specific regarding boost that I'm missing? In my searching on google I've seen a number of other people get this error but no one seems to have come up with a satisfactory solution.

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  • using yield in C# like I would in Ruby

    - by Sarah Vessels
    Besides just using yield for iterators in Ruby, I also use it to pass control briefly back to the caller before resuming control in the called method. What I want to do in C# is similar. In a test class, I want to get a connection instance, create another variable instance that uses that connection, then pass the variable to the calling method so it can be fiddled with. I then want control to return to the called method so that the connection can be disposed. I guess I'm wanting a block/closure like in Ruby. Here's the general idea: private static MyThing getThing() { using (var connection = new Connection()) { yield return new MyThing(connection); } } [TestMethod] public void MyTest1() { // call getThing(), use yielded MyThing, control returns to getThing() // for disposal } [TestMethod] public void MyTest2() { // call getThing(), use yielded MyThing, control returns to getThing() // for disposal } ... This doesn't work in C#; ReSharper tells me that the body of getThing cannot be an iterator block because MyThing is not an iterator interface type. That's definitely true, but I don't want to iterate through some list. I'm guessing I shouldn't use yield if I'm not working with iterators. Any idea how I can achieve this block/closure thing in C# so I don't have to wrap my code in MyTest1, MyTest2, ... with the code in getThing()'s body?

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  • On XP, how do I get the tooltip to appear above a transclucent form?

    - by Daniel Stutzbach
    I have an form with an Opacity less then 1.0. I have a tooltip associated with a label on the form. When I hover the mouse over the label, the tooltip shows up under the form instead of over the form. If I leave the Opacity at its default value of 1.0, the tooltip correctly appears over the form. However, my form is obviously no longer translucent. ;-) I have tried manually adjusting the position of the ToolTip with SetWindowPos() and creating a ToolTip "by hand" using CreateWindowEx(), but the problem remains. This makes me suspect its a Win32 API problem, not a problem with the Windows Forms implementation that runs on top of Win32. Why does the tooltip appear under the form, and, more importantly, how can I get it to appear over the form where it should? Edit: this appears to be an XP-only problem. Vista and Windows 7 work correctly. I'd still like to find a workaround to get the tooltip to appear above the form on XP. Here is a minimal program to demonstrate the problem: using System; using System.Windows.Forms; public class Form1 : Form { private ToolTip toolTip1; private Label label1; [STAThread] static void Main() { Application.EnableVisualStyles(); Application.SetCompatibleTextRenderingDefault(false); Application.Run(new Form1()); } public Form1() { toolTip1 = new ToolTip(); label1 = new Label(); label1.Location = new System.Drawing.Point(105, 127); label1.Text = "Hover over me"; label1.AutoSize = true; toolTip1.SetToolTip(label1, "This is a moderately long string, " + "designed to be very long so that it will also be quite long."); ClientSize = new System.Drawing.Size(292, 268); Controls.Add(label1); Opacity = 0.8; } }

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  • How to make a program not show up in Alt-Tab or on the taskbar.

    - by Scott Chamberlain
    I have a program that needs to sit in the background and when a user connects to a RDP session it will do some stuff then launch a program. when the program is closed it will do some housekeeping and logoff the session. The current way I am doing it is like this I have the terminal server launch this application. I have it set as a windows forms application and my code is this public static void Main() { //Do some setup work Process proc = new Process(); //setup the process proc.Start(); proc.WaitForExit(); //Do some housecleaning NativeMethods.ExitWindowsEx(0, 0); } I really like this because there is no item in the taskbar and there is nothing showing up in alt-tab. However to do this I gave up access to functions like void WndProc(ref Message m) So Now I can't listen to windows messages (Like WTS_REMOTE_DISCONNECT or WTS_SESSION_LOGOFF) and do not have a handle to use for for bool WTSRegisterSessionNotification(IntPtr hWnd, int dwFlags); I would like my code to be more robust so it will do the housecleaning if the user logs off or disconnects from the session before he closes the program. Any reccomendations on how I can have my cake and eat it too?

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  • How can I use a meter-style progress bar?

    - by Yadyn
    In Vista/7, the Windows Explorer shell window makes use of a special kind of static progress bar to display hard drive space. With default styles, this bar is blue colored and non-animated. It also turns red colored when it gets close to being full (low disk space). Using messaging, I can tell the Windows Forms ProgressBar control to update its state to Paused and Error (yellow and red colored, respectively), which works fine, but these are still specific to progress. In the Windows User Experience Guidelines, it specifically points out this "meter" variant of the Progress Bar: This pattern isn't a progress bar, but it is implemented using the progress bar control. Meters have a distinct look to differentiate them from true progress bars. They say it "is implemented using the progress bar control", so... how? What message could I send to the control to have it behave this way? I've seen that you can send messages for setting the bar color, but the documentation says these calls are ignored when visual styles are enabled. Nothing else in the Windows API documentation for raw ProgressBar controls seemed to suggest a way to do this. Am I just stuck making a custom drawn bar? I'd really like to utilize the OS whenever possible so that the application will appear consistent throughout different OS versions. I realize that pre-Vista versions probably won't support this, though. I'm looking for a Windows Forms solution, but I wonder if it is even exposed at all via Win32 API.

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  • how to update a table in c# using oledb parameters?

    - by sameer
    I am having a table which has three fields, namely LM_code,M_Name,Desc. LC_code is a autogenerated string Id, keeping this i am updating M_Name and Desc. I used normal update command, the value is passing in runtime but the fields are not getting updated. I hope using oledb parameters the fileds can be updated. Any help will be appreciated... Here is my code. public void Modify() { String query = "Update Master_Accounts set (M_Name='" + M_Name + "',Desc='" + Desc + "') where LM_code='" + LM_code + "'"; DataManager.RunExecuteNonQuery(ConnectionString.Constr, query); } In DataManager Class i am executing the query string. public static void RunExecuteNonQuery(string Constr, string query) { OleDbConnection myConnection = new OleDbConnection(Constr); try { myConnection.Open(); OleDbCommand myCommand = new OleDbCommand(query, myConnection); myCommand.ExecuteNonQuery(); } catch (Exception ex) { string Message = ex.Message; throw ex; } finally { if (myConnection.State == ConnectionState.Open) myConnection.Close(); } } private void toolstModify_Click_1(object sender, EventArgs e) { txtamcode.Enabled = true; jewellery.LM_code = txtamcode.Text; jewellery.M_Name = txtaccname.Text; jewellery.Desc = txtdesc.Text; jewellery.Modify(); MessageBox.Show("Data Updated Succesfully"); }

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  • Flash compiler error 1061: Call to a possibly undefined method run... but run exists!

    - by Zane Geiger
    So I've been working on making a game in Processing but I think Flash would be a better way to get more people playing it, so I've decided to learn Flash. The problem is that I keep getting really stupid errors on incredibly simple things. For instance, I want to make a 'Block' object to use in a platform game. So I make a new .as file, name it Block.as, and define the Block class within it like so: package { public class Block { public function Block() { // constructor code } public function run() { } } } I don't want to add the code yet, I just want to ensure that this works. So in my main timeline code, I try to create an instance of the Block object and execute its run method: var block1:Block = new Block(); block1.run(); Every time it gives me this inane error: Scene 1, Layer 'Layer 1', Frame 1, Line 2 1061: Call to a possibly undefined method run through a reference with static type Block. What undefined method!? It's defined RIGHT THERE in Block.as. The class file is even in the same folder and everything. I'm getting REALLY annoyed at how poorly Flash handles such a ridiculously simple project. Does anyone know why Flash hates me?

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  • Why do I get this strange output behavior?

    - by WilliamKF
    I have the following program test.cc: #include <iostream> unsigned char bogus1[] = { // Changing # of periods (0x2e) changes output after periods. 0x2e, 0x2e, 0x2e, 0x2e }; unsigned int bogus2 = 1816; // Changing this value changes output. int main() { std::clog << bogus1; } I build it with: g++ -g -c -o test.o test.cc; g++ -static-libgcc -o test test.o Using g++ version 3.4.6 I run it through valgrind and nothing is reported wrong. However the output has two extra control characters and looks like this: .... Thats a control-X and a control-G at the end. If you change the value of bogus2 you get different control characters. If you change the number of periods in the array the issue goes away or changes. I suspect it is a memory corruption bug in the compiler or iostream package. What is going on here?

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  • Dereferencing the null pointer

    - by zilgo
    The standard says that dereferencing the null pointer leads to undefined behaviour. But what is "the null pointer"? In the following code, what we call "the null pointer": struct X { static X* get() { return reinterpret_cast<X*>(1); } void f() { } }; int main() { X* x = 0; (*x).f(); // the null pointer? (1) x = X::get(); (*x).f(); // the null pointer? (2) x = reinterpret_cast<X*>( X::get() - X::get() ); (*x).f(); // the null pointer? (3) (*(X*)0).f(); // I think that this the only null pointer here (4) } My thought is that dereferencing of the null pointer takes place only in the last case. Am I right? Is there difference between compile time null pointers and runtime according to C++ Standard?

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  • grails question (sample 1 of Grails To Action book) problem with Controller and Service

    - by fegloff
    Hi, I'm doing Grails To Action sample for chapter one. Every was just fine until I started to work with Services. When I run the app I have the following error: groovy.lang.MissingPropertyException: No such property: quoteService for class: qotd.QuoteController at qotd.QuoteController$_closure3.doCall(QuoteController.groovy:14) at qotd.QuoteController$_closure3.doCall(QuoteController.groovy) at java.lang.Thread.run(Thread.java:619) Here is my groovie QuoteService class, which has an error within the definition of GetStaticQuote (ERROR: Groovy:unable to resolve class Quote) package qotd class QuoteService { boolean transactional = false def getRandomQuote() { def allQuotes = Quote.list() def randomQuote = null if (allQuotes.size() > 0) { def randomIdx = new Random().nextInt(allQuotes.size()) randomQuote = allQuotes[randomIdx] } else { randomQuote = getStaticQuote() } return randomQuote } def getStaticQuote() { return new Quote(author: "Anonymous",content: "Real Programmers Don't eat quiche") } } Controller groovie class package qotd class QuoteController { def index = { redirect(action: random) } def home = { render "<h1>Real Programmers do not each quiche!</h1>" } def random = { def randomQuote = quoteService.getRandomQuote() [ quote : randomQuote ] } def ajaxRandom = { def randomQuote = quoteService.getRandomQuote() render "<q>${randomQuote.content}</q>" + "<p>${randomQuote.author}</p>" } } Quote Class: package qotd class Quote { String content String author Date created = new Date() static constraints = { author(blank:false) content(maxSize:1000, blank:false) } } I'm doing the samples using Eclipse with grails addin. Any advice? Regards, Francisco

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  • WPF ObservableCollection in xaml

    - by Cloverness
    Hi, I have created an ObservableCollection in the code behind of a user control. It is created when the window loads: private void UserControl_Loaded(object sender, RoutedEventArgs e) { Entities db = new Entities(); ObservableCollection<Image> _imageCollection = new ObservableCollection<Image>(); IEnumerable<library> libraryQuery = from c in db.ElectricalLibraries select c; foreach (ElectricalLibrary c in libraryQuery) { Image finalImage = new Image(); finalImage.Width = 80; BitmapImage logo = new BitmapImage(); logo.BeginInit(); logo.UriSource = new Uri(c.url); logo.EndInit(); finalImage.Source = logo; _imageCollection.Add(finalImage); } } I need to get the ObservableCollection of images which are created based on the url saved in a database. But I need a ListView or other ItemsControl to bind to it in XAML file like this: But I can't figure it out how to pass the ObservableCollection to the ItemsSource of that control. I tried to create a class and then create an instance of a class in xaml file but it did not work. Should I create a static resource somehow Any help will be greatly appreciated.

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  • Multidimensional data structure?

    - by Austin Truong
    I need a multidimensional data structure with a row and a column. Must be able to insert elements any location in the data structure. Example: {A , B} I want to insert C in between A and B. {A, C, B}. Dynamic: I do not know the size of the data structure. Another example: I know the [row][col] of where I want to insert the element. EX. insert("A", 1, 5), where A is the element to be inserted, 1 is the row, 5 is the column. EDIT I want to be able to insert like this. static void Main(string[] args) { Program p = new Program(); List<string> list = new List<string>(); list.Insert(1, "HELLO"); list.Insert(5, "RAWR"); for (int i = 0; i < list.Count; i++) { Console.WriteLine(list[i]); } Console.ReadKey(); } And of course this crashes with an out of bounds error. So in a sense I will have a user who will choose which ROW and COL to insert the element to.

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  • java gui image problem : doesn't display in the background

    - by thegamer
    Hello, i have a query about why is my image not being displayed in my background of my program. I mean i did all the steps necessary and still it would'nt be displayed. The code runs perfectly but without having the image displayed. The directory is written in the good location of the image. I am using java with gui. If anyone could help me solve my problem, i would appreciate :) here is the code below: import java.awt.*; import java.awt.event.*; import javax.swing.*; public class hehe extends JPanel{ public hehe(){ setOpaque(false); setLayout(new FlowLayout()); } public static void main (String args[]){ JFrame win = new JFrame("yooooo"); // it is automaticcally hidden JPanel mainPanel = new JPanel(new BorderLayout()); win.add(mainPanel); JLabel titleLabel = new JLabel("title boss"); titleLabel.setFont(new Font("Arial",Font.BOLD,18)); titleLabel.setForeground(Color.blue); mainPanel.add(titleLabel,BorderLayout.NORTH); win.setSize(382,269); // the dimensions of the image win.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); win.setVisible(true); } public void paint(Graphics g) { Image a = Toolkit.getDefaultToolkit().getImage("C:\\Users\\andrea\\Desktop\\Gui\\car"); // car is the name of the image file and is in JPEG g.drawImage(a,0,0,getSize().width,getSize().height,this); super.paint(g); } }

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  • First and last UITableViewCell keep changing while scrolling.

    - by W Dyson
    I have a tableView with cells containing one UITextField as a subview for each cell. My problem is that when I scroll down, the text in the first cell is duplicated in the last cell. I can't for the life if me figure out why. I have tried loading the cells from different nibs, having the textFields as ivars. The UITextFields don't seem to be the problem, I'm thinking it has something to do with the tableView reusing the cells. The textFields all have a data source that keeps track of the text within the textField and the text is reset each time the cell is shown. Any ideas? UPDATE: Thanks guys, here's a sample: - (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath { NSLog(@"Section %i, Row %i", indexPath.section, indexPath.row); static NSString *JournalCellIdentifier = @"JournalCellIdentifier"; UITableViewCell *cell = (UITableViewCell *)[self.tableView dequeueReusableCellWithIdentifier:JournalCellIdentifier]; if (cell == nil) { cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:JournalCellIdentifier] autorelease]; cell.selectionStyle = UITableViewCellSelectionStyleNone; cell.accessoryType = UITableViewCellAccessoryNone; } if (indexPath.section == 0) { UITextField *textField = (UITextField *)[self.authorCell viewWithTag:1]; [cell addSubview:textField]; self.authorTextField = textField; self.authorTextField.text = [self.textFieldDictionary objectForKey:@"author"]; NSLog(@"Reading Author:%@", [self.textFieldDictionary objectForKey:@"author"]); } else if (indexPath.section == 1) { UITextField *textField = (UITextField *)[self.yearCell viewWithTag:1]; [cell addSubview:textField]; self.yearTextField = textField; self.yearTextField.text = [self.textFieldDictionary objectForKey:@"year"]; NSLog(@"Reading Year:%@", [self.textFieldDictionary objectForKey:@"year"]); } else if (indexPath.section == 2) { UITextField *textField = (UITextField *)[self.volumeCell viewWithTag:1]; [cell addSubview:textField]; self.volumeTextField = textField; self.volumeTextField.text = [self.textFieldDictionary objectForKey:@"volume"]; NSLog(@"Reading Volume:%@", [self.textFieldDictionary objectForKey:@"volume"]); } return cell; }

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  • Question about using an access database as a resource file in Visual Studio.

    - by user354303
    Hi I am trying to embed a Microsoft Access database file into my Class assembly DLL. I want my code to reference the resource file and use it with a ADODB.Connection object. Any body know a simpler way, or an easier way? Or what is wrong with my code, when i added the resource file it added me dataset definitions, but i have no idea what to do with those. The connection string I am trying below is from an automatically generated app.config. I did add the item as a resource... using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Data; using ConsoleApplication1.Resources;//SPPrinterLicenses using System.Data.OleDb; using ADODB; using System.Configuration; namespace ConsoleApplication1 { class SharePointPrinterManager { public static bool IsValidLicense(string HardwareID) { OleDbDataAdapter da = new OleDbDataAdapter(); DataSet ds = new DataSet(); ADODB.Connection adoCn = new Connection(); ADODB.Recordset adoRs = new Recordset(); //**open command below fails** adoCn.Open( @"Provider=Microsoft.ACE.OLEDB.12.0;Data Source=|DataDirectory|\Resources\SPPrinterLicenses.accdb;Persist Security Info=True", "", "", 1); adoRs.Open("Select * from AllWorkstationLicenses", adoCn, ADODB.CursorTypeEnum.adOpenForwardOnly, ADODB.LockTypeEnum.adLockReadOnly, 1); da.Fill(ds, adoRs, "AllworkstationLicenses"); adoCn.Close(); DataTable dt = new DataTable(); //ds.Tables. return true; } } }

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  • Encrypt string with public key only

    - by vlahovic
    i'm currently working on a android project where i need to encrypt a string using 128 bit AES, padding PKCS7 and CBC. I don't want to use any salt for this. I've tried loads of different variations including PBEKey but i can't come up with working code. This is what i currently have: String plainText = "24124124123"; String pwd = "BobsPublicPassword"; byte[] key = pwd.getBytes(); key = cutArray(key, 16); byte[] input = plainText.getBytes(); byte[] output = null; SecretKeySpec keySpec = null; keySpec = new SecretKeySpec(key, "AES"); Cipher cipher = Cipher.getInstance("AES/CBC/PKCS7Padding"); cipher.init(Cipher.ENCRYPT_MODE, keySpec); output = cipher.doFinal(input); private static byte[] cutArray(byte[] arr, int length){ byte[] resultArr = new byte[length]; for(int i = 0; i < length; i++ ){ resultArr[i] = arr[i]; } return resultArr; } Any help appreciated //Vlahovic

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  • L2S DataContext out of synch: row not found or changed

    - by awrigley
    The Problem I am getting a number of errors that imply that the DataContext, or rather, the way I am using the DataContext is getting out of synch. The error occurs on db.SubmitChanges() where db is my DataContext instance. The error is: Row not found or changed. The problem only occurs intermitently, for example, adding a row then deleting it. If I stop the dev server and restart, the added row is there and I can delete it no problem. Ie, it seems that the problem is related to the DataContext losing track of the rows that have been added. IMPORTANT: Before anyone votes to close this thread, on the basis of it being a duplicate, I have checked the sql server profiler and there is no "Where 0 = 1" in the SQL. I have also recreated the dbml file, so am satisfied that the database schema is in synch with the schema represented by the dbml file. Ie, no cases of mismatched nullable/not nullable columns, etc. My Diagnosis (for what it is worth): It seems to be a problem related to how I am using the DataContext. I am new to MVC, Repositories and Services patterns, so suspect that I have wired things up wrong. The Setup Simple eLearning app in its early stages. Pupils need to be able to add and delete courses (Courses table) to their UserCourses. To do this, I have a service that gets a specific DataContext instance Dependency Injected into its constructor. Service Class Constructor: public class SqlPupilBlockService : IPupilBlockService { DataContext db; public SqlPupilBlockService(DataContext db) { this.db = db; CoursesRepository = new SqlRepository<Course>(db); UserCoursesRepository = new SqlRepository<UserCourse>(db); } // Etc, etc } The CoursesRepository and UserCoursesRepository are both private properties of the service class that are of Type IRepository (just a simple generic repository interface). Sql Respoitory Code: public class SqlRepository<T> : IRepository<T> where T : class { DataContext db; public SqlRepository(DataContext db) { this.db = db; } #region IRepository<T> Members public IQueryable<T> Query { get { return db.GetTable<T>(); } } public List<T> FetchAll() { return Query.ToList(); } public void Add(T entity) { db.GetTable<T>().InsertOnSubmit(entity); } public void Delete(T entity) { db.GetTable<T>().DeleteOnSubmit(entity); } public void Save() { db.SubmitChanges(); } #endregion } The two methods for adding and deleting UserCourses are: Service Methods for Adding and Deleting UserCourses: public void AddUserCourse(int courseId) { UserCourse uc = new UserCourse(); uc.IdCourse = courseId; uc.IdUser = UserId; uc.DateCreated = DateTime.Now; uc.DateAmended = DateTime.Now; uc.Role = "Pupil"; uc.CourseNotes = string.Empty; uc.ActiveStepIndex = 0; UserCoursesRepository.Add(uc); UserCoursesRepository.Save(); } public void DeleteUserCourse(int courseId) { var uc = (UserCoursesRepository.Query.Where(x => x.IdUser == UserId && x.IdCourse == courseId)).Single(); UserCoursesRepository.Delete(uc); UserCoursesRepository.Save(); } Ajax I am using Ajax via Ajax.BeginForm I don't think that is relevant. ASP.NET MVC 3 I am using mvc3, but don't think that is relevant: the errors are related to model code.

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  • Entity Framework LINQ Query using Custom C# Class Method - Once yes, once no - because executing on the client or in SQL?

    - by BrooklynDev
    I have two Entity Framework 4 Linq queries I wrote that make use of a custom class method, one works and one does not: The custom method is: public static DateTime GetLastReadToDate(string fbaUsername, Discussion discussion) { return (discussion.DiscussionUserReads.Where(dur => dur.User.aspnet_User.UserName == fbaUsername).FirstOrDefault() ?? new DiscussionUserRead { ReadToDate = DateTime.Now.AddYears(-99) }).ReadToDate; } The linq query that works calls a from after a from, the equivalent of SelectMany(): from g in oc.Users.Where(u => u.aspnet_User.UserName == fbaUsername).First().Groups from d in g.Discussions select new { UnReadPostCount = d.Posts.Where(p => p.CreatedDate > DiscussionRepository.GetLastReadToDate(fbaUsername, p.Discussion)).Count() }; The query that does not work is more like a regular select: from d in oc.Discussions where d.Group.Name == "Student" select new { UnReadPostCount = d.Posts.Where(p => p.CreatedDate > DiscussionRepository.GetLastReadToDate(fbaUsername, p.Discussion)).Count(), }; The error I get is: LINQ to Entities does not recognize the method 'System.DateTime GetLastReadToDate(System.String, Discussion)' method, and this method cannot be translated into a store expression. My question is, why am I able to use my custom GetLastReadToDate() method in the first query and not the second? I suppose this has something to do with what gets executed on the db server and what gets executed on the client? These queries seem to use the GetLastReadToDate() method so similarly though, I'm wondering why would work for the first and not the second, and most importantly if there's a way to factor common query syntax like what's in the GetLastReadToDate() method into a separate location to be reused in several different places LINQ queries. Please note all these queries are sharing the same object context.

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  • generic binary Search in c#

    - by Pro_Zeck
    Below is my Generic Binary Search it works ok with the intgers type array it finds all the elements in it . But the Problem Arises when i use a string array to find any string data. It runs ok for the first index and last index elements but i cant find the middle elements. Stringarray = new string[] { "b", "a", "ab", "abc", "c" }; public static void BinarySearch<T>(T[] array, T searchFor, Comparer<T> comparer) { int high, low, mid; high = array.Length - 1; low = 0; if (array[0].Equals(searchFor)) Console.WriteLine("Value {0} Found At Index {1}",array[0],0); else if (array[high].Equals(searchFor)) Console.WriteLine("Value {0} Found At Index {1}", array[high], high); else { while (low <= high) { mid = (high + low) / 2; if (comparer.Compare(array[mid], searchFor) == 0) { Console.WriteLine("Value {0} Found At Index {1}", array[mid], mid); break; } else { if (comparer.Compare(searchFor, array[mid]) > 0) high = mid + 1; else low = mid + 1; } } if (low > high) { Console.WriteLine("Value Not Found In the Collection"); } } }

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  • Is locking on the requested object a bad idea?

    - by Quick Joe Smith
    Most advice on thread safety involves some variation of the following pattern: public class Thing { private static readonly object padlock = new object(); private string stuff, andNonsense; public string Stuff { get { lock (Thing.padlock) { if (this.stuff == null) this.stuff = "Threadsafe!"; } return this.stuff; } } public string AndNonsense { get { lock (Thing.padlock) { if (this.andNonsense == null) this.andNonsense = "Also threadsafe!"; } return this.andNonsense; } } // Rest of class... } In cases where the get operations are expensive and unrelated, a single locking object is unsuitable because a call to Stuff would block all calls to AndNonsense, degrading performance. And rather than create a lock object for each call, wouldn't it be better to acquire the lock on the member itself (assuming it is not something that implements SyncRoot or somesuch for that purpose? For example: public string Stuff { get { lock (this.stuff) { // Pretend that this is a very expensive operation. if (this.stuff == null) this.stuff = "Still threadsafe and good?"; } return this.stuff; } } Strangely, I have never seen this approach recommended or warned against. Am I missing something obvious?

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  • Whats wrong with this method?

    - by David
    Here's the method: public static String CPUcolor () { System.out.println ("What color am I?") ; String s = getIns() ; System.out.println ("are you sure I'm "+s+"? (Y/N)") ; String a = getIns() ; while (!((a.equals ("y")) || (a.equals ("Y")) || (a.equals ("n")) || (a.equals ("N")))) { System.out.println ("try again") ; a = getIns () ; } if (a.equals ("n") || a.equals("N")) {CPUcolor() ;} System.out.println ("I am "+s) ; return s ; } here is a possible output of this method (y's and n's are user inputs): What color am I? red are you sure I'm red? (Y/N) N What color am I? blue are you sure I'm blue? (Y/N) N What color am I? Yellow are you sure I'm Yellow? (Y/N) y I am Yellow I am blue I am red Why is it that the line's "I am blue" and "I am Blue" printed? Why are they printed in reverse order with red, the first entered, printed last?

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  • Bind to a markup externsion property

    - by user314580
    Hi, I have written a markup extension which stores amongst others a help text. This help text is shown on the right side of the main window. This works fine. Now, I want to add a tooltip for every control. The content of the tooltip should be same as for the helptext extension. The XAML code: <ListView ctrl:ListViewLayoutManager.Enabled="true" x:Name="ListViewSources" ItemsSource="{Binding SourceItems}" ItemContainerStyle="{DynamicResource ListViewItemStyleAlternate}" Height="150" MinWidth="350" Helper:HelpExtension.IsControl="true" Helper:HelpExtension.HelpText="{x:Static strings:GUIResource.HelpProfilesSourcesDescriptionText}" > <ListView.ToolTip> <ToolTip Style="{DynamicResource Own_TooltipStyle}"></ToolTip> </ListView.ToolTip> And now the code of the style: If I run the program I get the binding error: System.Windows.Data Error: 39 : BindingExpression path error: 'Helper:HelpExtension' property not found on 'object' ''ListView' (Name='ListViewSources')'. BindingExpression:Path=Helper:HelpExtension.HelpText; DataItem='ListView' (Name='ListViewSources'); target element is 'TextBlock' (Name=''); target property is 'Text' (type 'String') Does anybody know how I can bind the TextBlock to the content of Helper:HelpExternsion.HelpText? Thanks Dieter

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  • GUID or int entity key with SQL Compact/EF4?

    - by David Veeneman
    This is a follow-up to an earlier question I posted on EF4 entity keys with SQL Compact. SQL Compact doesn't allow server-generated identity keys, so I am left with creating my own keys as objects are added to the ObjectContext. My first choice would be an integer key, and the previous answer linked to a blog post that shows an extension method that uses the Max operator with a selector expression to find the next available key: public static TResult NextId<TSource, TResult>(this ObjectSet<TSource> table, Expression<Func<TSource, TResult>> selector) where TSource : class { TResult lastId = table.Any() ? table.Max(selector) : default(TResult); if (lastId is int) { lastId = (TResult)(object)(((int)(object)lastId) + 1); } return lastId; } Here's my take on the extension method: It will work fine if the ObjectContext that I am working with has an unfiltered entity set. In that case, the ObjectContext will contain all rows from the data table, and I will get an accurate result. But if the entity set is the result of a query filter, the method will return the last entity key in the filtered entity set, which will not necessarily be the last key in the data table. So I think the extension method won't really work. At this point, the obvious solution seems to be to simply use a GUID as the entity key. That way, I only need to call Guid.NewGuid() method to set the ID property before I add a new entity to my ObjectContext. Here is my question: Is there a simple way of getting the last primary key in the data store from EF4 (without having to create a second ObjectContext for that purpose)? Any other reason not to take the easy way out and simply use a GUID? Thanks for your help.

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  • Calling from C# to C function which accept a struct array allocated by caller

    - by lifey
    I have the following C struct struct XYZ { void *a; char fn[MAX_FN]; unsigned long l; unsigned long o; }; And I want to call the following function from C#: extern "C" int func(int handle, int *numEntries, XYZ *xyzTbl); Where xyzTbl is an array of XYZ of size numEntires which is allocated by the caller I have defined the following C# struct: [System.Runtime.InteropServices.StructLayoutAttribute(System.Runtime.InteropServices.LayoutKind.Sequential, CharSet = System.Runtime.InteropServices.CharSet.Ansi)] public struct XYZ { public System.IntPtr rva; [System.Runtime.InteropServices.MarshalAsAttribute(System.Runtime.InteropServices.UnmanagedType.ByValTStr, SizeConst = 128)] public string fn; public uint l; public uint o; } and a method: [System.Runtime.InteropServices.DllImport(@"xyzdll.dll", CallingConvention = CallingConvention.Cdecl)] public static extern Int32 func(Int32 handle, ref Int32 numntries, [MarshalAs(UnmanagedType.LPArray)] XYZ[] arr); Then I try to call the function : XYZ xyz = new XYZ[numEntries]; for (...) xyz[i] = new XYZ(); func(handle,numEntries,xyz); Of course it does not work. Can someone shed light on what I am doing wrong ?

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  • In a combobox, how do I determine the highlighted item (not selected item)?

    - by Harold Bamford
    First, fair warning: I am a complete newbie with C# and WPF. I have a combobox (editable, searchable) and I would like to be able to intercept the Delete key and remove the currently highlighted item from the list. The behavior I'm looking for is like that of MS Outlook when entering in email addresses. When you give a few characters, a dropdown list of potential matches is displayed. If you move to one of these (with the arrow keys) and hit Delete, that entry is permanently removed. I want to do that with an entry in the combobox. Here is the XAML (simplified): <ComboBox x:Name="Directory" KeyUp="Directory_KeyUp" IsTextSearchEnabled="True" IsEditable="True" Text="{Binding Path=CurrentDirectory, Mode=TwoWay}" ItemsSource="{Binding Source={x:Static self:Properties.Settings.Default}, Path=DirectoryList, Mode=TwoWay}" / The handler is: private void Directory_KeyUp(object sender, KeyEventArgs e) { ComboBox box = sender as ComboBox; if (box.IsDropDownOpen && (e.Key == Key.Delete)) { TrimCombobox("DirectoryList", box.HighlightedItem); // won't compile! } } When using the debugger, I can see box.HighlightedItem has the value I want but when I try and put in that code, it fails to compile with: System.Windows.Controls.ComboBox' does not contain a definition for 'HighlightedItem'... So: how do I access that value? Keep in mind that the item has not been selected. It is merely highlighted as the mouse hovers over it. Thanks for your help.

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