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  • wpf how to bind a listbox to a list (two ways) - c#

    - by user429400
    Hi, I want to create a 2 way bind between a listbox and a .NET list. In my GUI, I have a listbox, a textbox and add and remove buttons. The listbox displays cars, and my goal is to create a 2way bind between the .Net car list and the listbox: when the user enters a car into the textbox, it gets updated only in the .Net list, and the listbox is updated automatically. When the user press the GUI "remove" button, a car gets removed from the GUI and the .Net list is updated automatically. I've started to write the xaml code, but figured that I don't actually know how to do the binding on both sides (c# and xaml): <Window x:Class="WpfApplication1.Window1" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:c="clr-namespace:WpfApplication1" Title="Window1" Height="300" Width="369" Loaded="Window_Loaded"> <Window.Resources> <ObjectDataProvider x:Key="carsData" ObjectType="{x:Type c:Window1}" /> </Window.Resources> <Grid Width="332"> <ListBox Margin="10,62,0,100" Name="myListBox" HorizontalAlignment="Left" Width="120" ItemsSource="{Binding Source={StaticResource CarsData}}"/> <Button Height="23" Margin="66,0,0,65" Name="addBtn" VerticalAlignment="Bottom" Click="addBtn_Click" HorizontalAlignment="Left" Width="64">add</Button> <TextBox Margin="10,0,0,64.48" Name="myTextBox" Height="23" VerticalAlignment="Bottom" HorizontalAlignment="Left" Width="47" /> <Button Height="23" Margin="66,0,0,33" Name="removeButton" VerticalAlignment="Bottom" HorizontalAlignment="Left" Width="64" Click="removeButton_Click">Remove</Button> </Grid> </Window> There is my c# code: namespace WpfApplication1 { public partial class Window1 : Window { MyModel listMgr; ObservableCollection carList; public Window1() { InitializeComponent(); listMgr = new MyModel(); } private void addBtn_Click(object sender, RoutedEventArgs e) { listMgr.add(new Car(0, myTextBox.Text, 2011)); } private void removeButton_Click(object sender, RoutedEventArgs e) { //myListBox.Items.RemoveAt(0); } private void Window_Loaded(object sender, RoutedEventArgs e) { carList = listMgr.getList(); myListBox.DataContext = carList; //secondListBox.DataContext = carList; } } } Thanks, Li

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  • ArrayBlockingQueue exceeds given capacity

    - by Wojciech Reszelewski
    I've written program solving bounded producer & consumer problem. While constructing ArrayBlockingQueue I defined capacity 100. I'm using methods take and put inside threads. And I've noticed that sometimes I see put 102 times with any take's between them. Why does it happen? Producer run method: public void run() { Object e = new Object(); while(true) { try { queue.put(e); } catch (InterruptedException w) { System.out.println("Oj, nie wyszlo, nie bij"); } System.out.println("Element added"); } } Consumer run method: public void run() { while(true) { try { queue.take(); } catch (InterruptedException e) { e.printStackTrace(); } System.out.println("Element removed"); } } Part of uniq -c on file with output: 102 Element removed 102 Element added 102 Element removed 102 Element added 102 Element removed 102 Element added 102 Element removed 102 Element added 102 Element removed 102 Element added 102 Element removed 102 Element added 2 Element removed 2 Element added 102 Element removed 102 Element added

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  • C++: conjunction of binds?

    - by Helltone
    Suppose the following two functions: #include <iostream> #include <cstdlib> // atoi #include <cstring> // strcmp #include <boost/bind.hpp> bool match1(const char* a, const char* b) { return (strcmp(a, b) == 0); } bool match2(int a, const char* b) { return (atoi(b) == a); } Each of these functions takes two arguments, but can be transformed into a callable object that takes only one argument by using (std/boost)bind. Something along the lines of: boost::bind(match1, "a test"); boost::bind(match2, 42); I want to be able to obtain, from two functions like these that take one argument and return bool, a callable object that takes two arguments and returns the && of the bools. The type of the arguments is arbitrary. Something like an operator&& for functions that return bool.

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  • How are value types implemented in .NET

    - by Michael
    Been looking around the net and can't find any articles about how value types are actually implemented. For instance, an Int32 is a struct and it's direct parent is System.ValueType and that's ultimate parent is System.Object. Object is a class - I imagine ValueType is a class? What's the class hierarchy? What part does the CLR have to play? At what stage and how does the CLR know to allocate value types to the stack? (FYI, I am aware that value types are stored where they are declared).

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  • Custom iterator for dictionary?

    - by aaginor
    Hi folks, in my C#-Application, I have a Dictionary object. When iterating over the object using foreach, I naturally get each element of the dictionary. But I want only certain elements to be iterated, depending on the value of a property of MyValue. class MyValue { public bool AmIIncludedInTheIteration { get; set; } ... } Whenever AmIIncludedInTheIteration is false, the item shall not be returned by foreach. I understand that I need to implement my own iterator and override the Dictionary-Iterator somewhere. Can anyone here give me a short HowTo? Thanks in advance, Frank

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  • Pass parameter from page to ActiveX

    - by nCdy
    <object id="Bacs_DBTableRepX" classid="CLSID:CA8B72B3-3B15-40D7-9364-478E25AF5B41" codebase="Bacs_DBTableRepX.cab" style=" Z-INDEX: 102; LEFT: 20px; WIDTH: 1200px; POSITION: absolute; TOP: 80px; HEIGHT: 600px"> <param name="ax_Command" value='<%=GetText()%>'/> </object> Here is my try but it made no sense. Parameter had not being sent. Is there any examples how to sent parameter to my ActiveX or some mistakes in my code ?

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  • C# Container Class

    - by Jamie
    I'm building a game in c# which allows you to script your own level, although I have come across a bit of a thought. I have a base class called "World" as an object. This was made with a simple: class World { However, when the user is scripting their level, all of the game objects will be contained in the world object. I want them to be able to do something on the lines of: World.ParentObjectName.ParentObjectProperty = "abc"; I know that the System.Windows.Forms.Panel and other classes are like containers and can have objects in them and be accessed in that kind of way... my question is how can I make a class which is like a container in which I can add objects to, and then access them with a World.ObjectName I have tried class World : System.Collections.CollectionBase, but with this method, I have to keep typing World.Item("ObjectName") Can anyone help? Thanks!

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  • How do I check for Existence of a Record in GAE

    - by VDev
    I am trying to create a simple view in Django & GAE, which will check if the user has a profile entity and prints a different message for each case. I have the program below, but somehow GAE always seem to return a object. My program is below import datetime from django.http import HttpResponse, HttpResponseRedirect from google.appengine.api import users from google.appengine.ext import db from models import Profile import logging #from accounts.views import profile # Create your views here. def login_view(request): user = users.get_current_user() profile = db.GqlQuery("SELECT * FROM Profile WHERE account = :1", users.get_current_user()) logging.info(profile) logging.info(user) if profile: return HttpResponse("Congratulations Your profile is already created.") else: return HttpResponse("Sorry Your profile is NOT created.") My model object is Profile defined as follows: class Profile(db.Model): first_name = db.StringProperty() last_name = db.StringProperty() gender = db.StringProperty(choices=set(["Male", "Female"])) account = db.UserProperty(required = True) friends = db.ListProperty(item_type=users.User) last_login = db.DateTimeProperty(required=True) Thanks for the help.

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  • Two way binding when setter is overriden

    - by Nicolas Goy
    I have an NSTextField bound to some object "zoom" property. In this object's class implementation, I have the following - (void)setZoom:(CGFloat)zoom { _zoom = MAX(0, MIN(10, zoom)); } If I write "-5" in the textfield, setZoom: will be called with "-5" as argument and _zoom will be set to 0. Then problem is that the textfield is not updating itself and it shows "-5" instead of re-reading the property value it has just set. If I do myObject.zoom = -5; in code, the text field will display 0 correctly. I tried to wrap _zoom =... inside willChangeValueForKey/didChangeValueForKey calls but it didn't change anything.

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  • Is it safe to unset PHP super-globals if this behavior is documented?

    - by Stephen
    I'm building a PHP framework, and in it I have a request object that parses the url as well as the $_GET, $_POST and $_FILE superglobals. I want to encourage safe web habits, so I'm protecting the data against SQL injection, etc. In order to ensure users of this framework are accessing the safe, clean data through the request object, I plan to use unset($_GET, $_POST, $_REQUEST); after parsing those variables. I will document this in the method comments, and explain in the framework documentation that this is happening. My question is: Would this be desirable behavior? What are the potential pitfalls that I have not foreseen?

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  • Browser not handling exception from AJAX panel, ASP.NET c#

    - by Grant
    Hi, i am having trouble catching errors in an AJAX panel. Even when i throw an exception in the c# code behind the front end completely ignores it. Here is the code i have setup, can anyone see why? I ideally want to show a js alert window on error. Code Behind: protected void btnX_Click(object sender, EventArgs e) { throw new ApplicationException("test"); } protected void ScriptManager_AsyncPostBackError(object sender, AsyncPostBackErrorEventArgs e) { ScriptManager.AsyncPostBackErrorMessage = e.Exception.Message; } Markup: <script type="text/javascript" language="javascript"> Sys.WebForms.PageRequestManager.getInstance().add_endRequest(EndRequestHandler); function EndRequestHandler(sender, e) { window.alert(e.get_error().name); } </script> <asp:ScriptManager ID="ScriptManager" runat="server" AllowCustomErrorsRedirect="true" OnAsyncPostBackError="ScriptManager_AsyncPostBackError" />

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  • How to display an icon on JOptionPane.showInputDialog() in Java?

    - by Lion
    The following segment of code shows JOptionPane.showInputDialog() method. It works fine but I need to display a custom icon on it. I currently left it null as shown below. String operatingSystem = System.getProperty("os.name"); Object o[] = {"Turn Off", "Restart", "Stand By", "Log Off"}; Frame frame = new Frame(operatingSystem); Object selectedValue = JOptionPane.showInputDialog(frame, "What would you like to do with the system?", "Select a task", JOptionPane.INFORMATION_MESSAGE, null, o, o[0]); //<---- Here it is. How can an icon be displayed on it replacing null?

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  • Can I have fixed typed ArrayList in C#, just like C++?

    - by Kazoom
    I have an ArrayList which contains fixed type of objects. However everytime I need to extract an object a particular index, I need to typecast it to my user defined type from object type. Is there a way in C# to declare ArrayList of fixed types just like Java and C++, or is there a work around to avoid the typecasting everytime? Edit: I apologize I forgot mentioning that I require the datastructure to be thread-safe, which List is not. Otherwise I would have just used a normal Array. But I want to save myself from the effort of explicitly locking and unlocking while writing the array. So I thought of using ArrayList, synchronize it, but it requires typecasting every time.

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  • Data persistance with BufferedReader and PrintWriter?

    - by Nazgulled
    I have this simple application with a couple of classes which are all related. There's one, the main one, for which there is only one instance of. I need to save save and load that using a text stream. My instructor requirement is BufferedReader to load the stream and PrintWriter to save it. But is this even possible? To persist a data object/class with a text stream? I know how to do it with and object, using serialization. But I don't see how am I supposed to do it using text streams. Suggestions?

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  • Java template classes using generator or similar?

    - by Hugh Perkins
    Is there some library or generator that I can use to generate multiple templated java classes from a single template? Obviously Java does have a generics implementation itself, but since it uses type-erasure, there are lots of situations where it is less than adequate. For example, if I want to make a self-growing array like this: class EasyArray { T[] backingarray; } (where T is a primitive type), then this isn't possible. This is true for anything which needs an array, for example high-performance templated matrix and vector classes. It should probably be possible to write a code generator which takes a templated class and generates multiple instantiations, for different types, eg for 'double' and 'float' and 'int' and 'String'. Is there something that already exists that does this? Edit: note that using an array of Object is not what I'm looking for, since it's no longer an array of primitives. An array of primitives is very fast, and uses only as much space a sizeof(primitive) * length-of-array. An array of object is an array of pointers/references, that points to Double objects, or similar, which could be scattered all over the place in memory, require garbage collection, allocation, and imply a double-indirection for access. Edit2: good god, voted down for asking for something that probably doesn't currently exist, but is technically possible and feasible? Does that mean that people looking for ways to improve things have already left the java community? Edit3: Here is code to show the difference in performance between primitive and boxed arrays: int N = 10*1000*1000; double[]primArray = new double[N]; for( int i = 0; i < N; i++ ) { primArray[i] = 123.0; } Object[] objArray = new Double[N]; for( int i = 0; i < N; i++ ) { objArray[i] = 123.0; } tic(); primArray = new double[N]; for( int i = 0; i < N; i++ ) { primArray[i] = 123.0; } toc(); tic(); objArray = new Double[N]; for( int i = 0; i < N; i++ ) { objArray[i] = 123.0; } toc(); Results: double[] array: 148 ms Double[] array: 4614 ms Not even close!

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  • Where do I put the Current user query so as to not repeat per controller?

    - by Kevin
    I have a standard query that gets the current user object: @user = User.find_by_email(session[:email]) but I'm putting it as the first line in every single controller action which is obviously not the best way to do this. What is the best way to refactor this? Do I put this as a method in the Application controller (and if so, can you just show me a quick example)? Do I put the entire @user object into the session (has about 50 columns and some sensitive ones like is_admin)? Or is there another way to remove this kind of redundancy?

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  • Form graphics not set when form loads

    - by Jimmy
    My form has a group box which contains two overlapping rectangles. The form's other controls are two sets of four numeric up down controls to set the rectangles' colors. (nudF1,2,3 and 4 set the rectangle that's in front, and nudB1,2,3 and 4 set the rectangle that's behind.) Everything works fine, except that the rectangles do not display the colors set in the numeric up downs when the form first loads. The numeric up down controls' ChangeValue events all call the ShowColors() method. The form's Load event calls the csColorsForm_Load() method. Any suggestions? namespace csColors { public partial class csColorsForm : Form { public csColorsForm() { InitializeComponent(); } private void csColorsForm_Load(object sender, EventArgs e) { this.BackColor = System.Drawing.Color.DarkBlue; SetColors(sender, e); } private void SetColors(object sender, EventArgs e) { Control control = (Control)sender; String ctrlName = control.Name; Graphics objGraphics; Rectangle rect1, rect2; int colorBack, colorFore; objGraphics = this.grpColor.CreateGraphics(); // If calling control is not a forecolor control, paint backcolor rectangle if (ctrlName.Substring(0,4)!="nudF") { colorBack = int.Parse(SetColorsB("nudB"), NumberStyles.HexNumber); SolidBrush BrushB = new SolidBrush(Color.FromArgb(colorBack)); rect1 = new Rectangle(this.grpColor.Left, this.grpColor.Top, this.grpColor.Width, this.grpColor.Height); objGraphics.FillRectangle(BrushB, rect1); } // Always paint forecolor rectangle colorFore = int.Parse(SetColorsB("nudF"), NumberStyles.HexNumber); SolidBrush BrushF = new SolidBrush(Color.FromArgb(colorFore)); rect2 = new Rectangle(this.grpColor.Left, this.grpColor.Top, this.grpColor.Width, this.grpColor.Height); objGraphics.FillRectangle(BrushF, rect2); objGraphics.Dispose(); } private string SetColorsB(string nam) { string txt=""; for (int n = 1; n <= 4; ++n) { var ud = Controls[nam + n] as NumericUpDown; int hex = (int)ud.Value; txt += hex.ToString("X2"); } return txt; } private void btnClose_Click(object sender, EventArgs e) { this.Close(); } } }

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  • Converting Byte[] to String - Interbase to C# - InvalidCastException

    - by NorthernOutpost
    I'm using OleDbDataReader rdr to read a "Comments" field in BLOB form (sub_type 1 segment size 80) into a string from an Interbase DB, and I keep getting exceptions. Any suggestions? Attempt #1 ls_Chap_Comments.Add((rdr["Comments"]).ToString()); InvalidCastException: The data value could not be converted for reasons other than sign mismatch or data overflow. For example, the data was corrupted in the data store but the row was still retrievable." Attempt #2 byte[] b = new byte[100]; b = (byte[])rdr["Comments"]; string s = System.Text.ASCIIEncoding.ASCII.GetString(b); InvalidCastException: Unable to cast object of type System.String to type System.Byte[] Attempt #3 // 17 is the BLOB column zero-based location for "Comments" retval = rdr.GetBytes(17, startIndex, outbyte, 0, bufferSize); InvalidCastException: Unable to cast object of type System.String to type System.Byte[]. Any suggestions would be really appreciated!

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  • Cleanest Way to Invoke Cross-Thread Events

    - by Nick
    I find that the .NET event model is such that I'll often be raising an event on one thread and listening for it on another thread. I was wondering what the cleanest way to marshal an event from a background thread onto my UI thread is. Based on the community suggestions, I've used this: // earlier in the code mCoolObject.CoolEvent+= new CoolObjectEventHandler(mCoolObject_CoolEvent); // then private void mCoolObject_CoolEvent(object sender, CoolObjectEventArgs args) { if (InvokeRequired) { CoolObjectEventHandler cb = new CoolObjectEventHandler( mCoolObject_CoolEvent); Invoke(cb, new object[] { sender, args }); return; } // do the dirty work of my method here }

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  • Is It Safe to Cast Away volatile?

    - by Yan Cheng CHEOK
    Most of the time, I am doing this way. class a { public: ~ a() { i = 100; // OK delete (int *)j; // Compiler happy. But, is it safe? // Error : delete j; } private: volatile int i; volatile int *j; }; int main() { a aa; } However, I saw an article here: https://www.securecoding.cert.org/confluence/display/seccode/EXP32-C.+Do+not+access+a+volatile+object+through+a+non-volatile+reference Casting away volatile allows access to an object through a non-volatile reference. This can result in undefined and perhaps unintended program behavior. So, what will be the workaround for my above code example?

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  • C# Event routing in code behind

    - by Nate
    I'm building a WPF MVVM-ish application. I want to be able to display an event log containing items in a collection that exists in my viewmodel. I want any of the objects in the model to be able to add data to the event log. Therefore every object needs to be able to pass data back to one central collection for databinding in the view. I could implement an event in every one of my data classes and manually pass the events up the object heirarchy but this seems super clumsy. On the visual tree a Routed Event would take care of this, is there some equivelent in the model scope? Any other ideas?

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  • problem-configure-jboss-to-work-with-jndi(3)

    - by Spiderman
    Sorry for opening new thread every time for the same problem. It's just that I'd like to refine my question during my investigation and it's hard to do it in stackoverflow structure on the same question (maybe on purpose). Anyway, in continuation to this thread http://stackoverflow.com/questions/2843218/problem-configure-jboss-to-work-with-jndi2 I discovered that when running an application that is deployed on my JBoss 4.2.3.GA, when I perform: Context initialContext = new InitialContext(); Object dataSource = initialContext.lookup("java:/DefaultDS"); I get null as a return value even though DefaultDS is the default datasource that comes with Jboss installation. and generally, how come initialContext return null value? if the datasource is not found it should throw NamingException and in other case it should return real object. What can I do with null? isn't it a bad error handling of javax.naming.InitialContext ???

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  • Java: Reflection against casting when you know superclass

    - by Ema
    I don't know exactly how to define my doubt so please be patient if the question has already been asked. Let's say I have to dinamically instantiate an object. This object will surely be instance of a subclass of a known, immutable class A. I can obtain dinamically the specific implementation class. Would it be better to use reflection exactly as if I didn't know anything about the target class, or would it be preferrable/possible to do something like: A obj = (Class.forName("com.package.Sub-A")) new A(); where Sub-A extends A ? The purpose would be to avoid reflection overhead times... Thank you in advance.

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  • What jQuery is triggered when a user selects a "drop down list" option

    - by Ankur
    I want to display a different form for different selections of this drop down list: <label> <select name="type" id="type"> <option value="object" selected="selected">Object</option> <option value="number">Number</option> <option value="text">Text</option> <option value="date">Date</option> <option value="time">Time</option> <option value="geo">Geospatial</option> <option value="currency">Currency</option> </select> </label> What would be the jQuery event that is triggered when a user selects one of these options. Would the .click() event be triggered in this case as well?

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  • How to create an image from canvas data?

    - by Jakub Hampl
    In my application I am trying to save an arbitrary part of a rendered HTML canvas to an image file. In my Javascript I call ctx.getImageData(x, y, w, h) and pass the resulting object to my macruby code (though if you know a solution in objc I am also very interested). There I'm trying to create a NSBitmapImageRep object so that I can then save to an image format the user desires. This is my code so far (the function gets a WebScriptObject as it's argument): def setimagedata(d) w = d.valueForKey("width").to_i h = d.valueForKey("height").to_i data = Pointer.new(:char, d.valueForKey("data").valueForKey("length").to_i) d.valueForKey("data").valueForKey("length").to_i.times do |i| data[i] = d.valueForKey("data").webScriptValueAtIndex(i).to_i end puts "data complete" # get's called @exported_image = NSBitmapImageRep.alloc.initWithBitmapDataPlanes(data, pixelsWide: w, pixelsHigh:h, bitsPerSample: 32, samplesPerPixel: 4, hasAlpha: true, isPlanar: false, colorSpaceName: NSCalibratedRGBColorSpace, bitmapFormat: NSAlphaNonpremultipliedBitmapFormat, bytesPerRow: 0, bitsPerPixel: 0) puts "done" # doesn't get called end The code doesn't seem to get through the initWithBitmapDataPlanes function but gives no error. My question is: what am I doing wrong? Is this approach reasonable (if not, what would be better?).

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