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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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  • Can I use Cassandra to store objects?

    - by Sandeep
    Hi, My application works like this. A database(Mysql) where there is a command. The command is an object(consists of fields many fields like ints ans strings). There is a webservice which interact with the database and get the command from the db and performs some operation. The way how I am storing the command into db is by stripping all the fields and inserting them in to the db. Can I use cassandra in place of mysql and store the command object?

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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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  • 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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  • Does this simple cache class need thread synchronization?

    - by DayOne
    Does this simple cache class need thread synchronization ... if I remove the lock _syncLock statement will encounter any problems? I think i can remove the locks as the references should be updated correctly right? ... BUt i'm think whar happens if client code is iterating over the GetMyDataStructure method and it get replaced? Thanks! public sealed class Cache { private readonly object _syncLock = new object(); private IDictionary<int, MyDataStructure> _cache; public Cache() { Refresh(); } public void Refresh() { lock (_syncLock) { _cache = DAL.GetMyDataStructure(); } } public IDictionary<int, MyDataStructure> **GetMyDataStructure**() { lock (_syncLock) { return _cache; } } }

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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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  • 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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  • Using locks inside a loop

    - by Xaqron
    // Member Variable private readonly object _syncLock = new object(); // Now inside a static method foreach (var lazyObject in plugins) { if ((string)lazyObject.Metadata["key"] = "something") { lock (_syncLock) { if (!lazyObject.IsValueCreated) lazyObject.value.DoSomething(); } return lazyObject.value; } } Here I need synchronized access per loop. There are many threads iterating this loop and based on the key they are looking for, a lazy instance is created and returned. lazyObject should not be created more that one time. Although Lazy class is for doing so and despite of the used lock, under high threading I have more than one instance created (I track this with a Interlocked.Increment on a volatile shared int and log it somewhere). The problem is I don't have access to definition of Lazy and MEF defines how the Lazy class create objects. My questions: 1) Why the lock doesn't work ? 2) Should I use an array of locks instead of one lock for performance improvement ?

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  • Powershell - remote folder availability while counting files

    - by ziklop
    I´m trying to make a Powershell script that reports if there´s a file older than x minutes on remote folder. I make this: $strfolder = 'folder1 ..................' $pocet = (Get-ChildItem \\server1\edi1\folder1\*.* ) | where-object {($_.LastWriteTime -lt (Get-Date).AddDays(-0).AddHours(-0).AddMinutes(-20))} | Measure-Object if($pocet.count -eq 0){Write-Host $strfolder "OK" -foreground Green} else {Write-Host $strfolder "ERROR" -foreground Red} But there´s one huge problem. The folder is often unavailable for me bacause of the high load and I found out when there is no connection it doesn´t report an error but continues with zero in $pocet.count. It means it reports everything is ok when the folder is unavailable. I was thinking about using if(Test-Path..) but what about it became unavailable just after passing Test-Path? Does anyone has a solution please? Thank you in advance

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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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  • 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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  • Lifetime of implicitly casted temporaries

    - by Answeror
    I have seen this question. It seems that regardless of the cast, the temporary object(s) will "survive" until the fullexpression evaluated. But in the following scenario: void foo(boost::tuple<const double&> n) { printf("%lf\n", n.get<0>()); } int main() { foo(boost::tuple<const double&>(2));//#1 foo(boost::make_tuple(2));//#2 return 0; } 1 run well, but 2 do not. And MSVC gave me a warning about 2: "reference member is initialized to a temporary that doesn't persist after the constructor exits" Now I am wondering why they both make a temporary "double" object and pass it to boost::tuple<const double&> and only 2 failed.

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  • C# Asynchronous Sockets questions.

    - by ccppjava
    Based on my reading and testing, with asynchronous sockets, the socket itself can be passed using state object (IAsyncResult result), also if store the socket as a private field, it would be captured by the callback methods. I am wondering how the IAysnResult is kepted between the BeginXXX and ReceiveXXX? It looks to me that after the BeginXXX call and the method ends, the state object would be disposed by GC if there is no reference to it. In the case of private field, how the private field is shared between threads? (As far as I know, a callback is executed using a thread from the default thread pool, which would be considered as a new thread.) Many thanks, hope the questions themselves are clear.

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  • How to add Items to GridView in C# Windows Store App (Win8)

    - by flexage
    To keep things simple let's just say I have a c# Windows Store Project for Windows 8 that has the following items: GridView (PlatformsGrid) List«PlatformSearchResult» (allPlatforms) DataTemplate (PlatformDataTemplate) in standardstyles.xaml allPlatforms is a collection of "PlatformSearchResult"objects populated from an online API, and has the following 3 properties: ID Name Alias I am able to add a new item to the gridview for each object that exists in my allPlatforms collection, however the items are blank and do not show the data from my objects. A quick summary of the current code looks like this: XAML Markup: <!-- Platforms Content --> <GridView x:Name="PlatformsGrid" Grid.Row="1" CanReorderItems="True" CanDragItems="True" ItemTemplate="{StaticResource PlatformDataTemplate}" > <GridView.ItemsPanel> <ItemsPanelTemplate> <WrapGrid MaximumRowsOrColumns="2" VerticalChildrenAlignment="Top" HorizontalChildrenAlignment="Center" /> </ItemsPanelTemplate> </GridView.ItemsPanel> </GridView> Data Template <!-- Platform Item Template --> <DataTemplate x:Key="PlatformDataTemplate"> <Grid Background="#FF939598" Height="250" Width="250"> <Image Source="/SampleImage.png" Stretch="UniformToFill"/> <StackPanel Orientation="Vertical" Background="#CC000000" Height="90" VerticalAlignment="Bottom"> <TextBlock Text="{Binding Name}" Margin="10,3,0,0" Width="242" Height="62" TextTrimming="WordEllipsis" TextWrapping="Wrap" HorizontalAlignment="Left"/> <TextBlock Text="{Binding Alias}" Margin="10,2,0,0" Width="186" Height="14" TextTrimming="WordEllipsis" HorizontalAlignment="Left" FontSize="9" Opacity="0.49"/> </StackPanel> </Grid> </DataTemplate> Controlling Function private async void FetchItemInfo_Loaded(object sender, RoutedEventArgs e) { // Get List of Top Games List<PlatformSearchResult> allPlatforms = new List<PlatformSearchResult>(); allPlatforms = await GamesDB.GetPlatforms(); // Dynamically Create Platform Tiles foreach (PlatformSearchResult platform in allPlatforms) { PlatformsGrid.DataContext = platform; PlatformsGrid.Items.Add(platform); } } How do I get the added items to show the appropriate object properties (ignoring the image for now), I'm just interested in populating the content of the TextBlocks. I appreciate any help anyone can provide! Thanks, Alex.

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  • Multi-threading concept and lock in c#

    - by Neeraj
    I read about lock, though not understood nothing at all. My question is why do we use a un-used object and lock that and how this makes something thread-safe or how this helps in multi-threading ? Isn't there other way to make thread-safe code. public class test { private object Lock { get; set; } ... lock (this.Lock) { ... } ... } Sorry is my question is very stupid, but i don't understand, although i've used it many times.

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  • An array of MySQL results...

    - by Michael Falk
    What am I doing wrong here? I am attempting to return a json object and I can't seem to get past the array... I've built hundreds of regular array and returned them as a json object but I am having a hard time wrapping my head around this one. $rows = array(); $post_array = array(); $i = 0; $result = mysql_query(" SELECT * FROM forum_posts WHERE permalink = '$permalink' AND LOWER(raw_text) LIKE '%$str%' " ); while($row = mysql_fetch_assoc($result)) { $post_array[$i] = $rows[ "id" => htmlentities($row["id"]), "post_content" => htmlentities($row["content"]), "author" => $row["author"], "last_updated" => $row["last_updated"], "author_id" => $row["author_id"], "editing_author" => $row["editing_author"], "date" => $outputQuoteDate ]; $i++; }

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  • Help understanding this stack trace

    - by user80632
    Hi I have health monitoring turned on, and i have the following error i'm trying to understand: Exception: Exception information: Exception type: System.InvalidCastException Exception message: Specified cast is not valid. Thread information: Thread ID: 5 Thread account name: NT AUTHORITY\NETWORK SERVICE Is impersonating: False Stack trace: at _Default.Repeater1_ItemDataBound(Object sender, RepeaterItemEventArgs e) at System.Web.UI.WebControls.Repeater.CreateControlHierarchy(Boolean useDataSource) at System.Web.UI.WebControls.Repeater.OnDataBinding(EventArgs e) at _Default.up1_Load() at _Default.Timer1_Tick(Object sender, EventArgs e) at System.Web.UI.Timer.OnTick(EventArgs e) at System.Web.UI.Page.RaisePostBackEvent(IPostBackEventHandler sourceControl, String eventArgument) at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) I'm just trying to figure out exactly where the problem is happening and what it is - is it happening in the Repeater1_ItemDataBound sub routine, or in the Timer1_Tick sub routine? Is the last thing that happened before the error occured at the top or bottom of the trace? any help much appreciated thanks

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  • Converting BindingList(Of T) to Array

    - by George
    Public Class Orders Inherits System.ComponentModel.BindingList(Of Order) End Class Public Sub DataBind(ByVal Orders() As Orders) End Sub Dim MyOrders() As Order = Orders.ToArray SuperListBinder.DataBind(MyOrders) '<<Error occurs on this line I don't understand this error. I think that I am passing the appropriate data type to a sub. I don't understand the meaning of "Cannot convert object of type x to an object of type x! Note that, if relevant, my Solution File contains ,multiple projects and that they are all project references. Error: Error 1 Value of type '1-dimensional array of BESI.BusinessObjects.Order' cannot be converted to '1-dimensional array of BESI.BusinessObjects.Orders' because 'BESI.BusinessObjects.Order' is not derived from 'BESI.BusinessObjects.Orders'. C:\My\Code\BESI\BesiAdmin\Forms\Activity.vb 17 34 BesiAdmin

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  • Python: Using `copyreg` to define reducers for types that already have reducers

    - by cool-RR
    (Keep in mind I'm working in Python 3, so a solution needs to work in Python 3.) I would like to use the copyreg module to teach Python how to pickle functions. When I tried to do it, the _Pickler object would still try to pickle functions using the save_global function. (Which doesn't work for unbound methods, and that's the motivation for doing this.) It seems like _Pickler first tries to look in its own dispatch for the type of the object that you want to pickle before looking in copyreg.dispatch_table. I'm not sure if this is intentional. Is there any way for me to tell Python to pickle functions with the reducer that I provide?

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  • Casting as Interface? Awesome.

    - by cam
    I was just experimenting around with one of my programs, trying to make it looks prettier and I found something interesting. I have an interface that 4 classes inherit from. I found that if I pass the Class as an object to a method like so: ClassTest classtest = new ClassTest(); DoOperation(classtest); private void DoOperation(object o) { ((InterfaceClass)o).DoThis(); } So I can pass any type of class that inherits from InterfaceClass, and it will preform the proper interface operation? This is the coolest thing I've ever found from OOP (something I've never really studied) I really thought interfaces were created for the sole purpose of organization for developers. Are there more uses for interfaces than this?

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  • How to get the required value displayed from the given array?

    - by Parth
    From below array i want the value of "_sql" to be displayed or we can I want to echo the "_sql" value, so what should be the syntax to display it in PHP code? JTableMenu Object ( [lft] => [rgt] => [home] => [_tbl] => #__menu [_tbl_key] => id [_db] => JDatabaseMySQL Object ( [name] => mysql [_nullDate] => 0000-00-00 00:00:00 [_nameQuote] => ` [_sql] => INSERT INTO `jos_menu` ( `id`,`menutype`,`name`,`alias`,`link`,`type`,`published`,`componentid`,`parent`,`ordering`,`checked_out`,`checked_out_time`,`brow............ [_errorNum] => 0 ) )

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  • Not found in protocol

    - by Alex
    I've subclassed MKAnnotation so that i can assign objects to annotations and then assign this object to a view controller like so: - (void)mapView:(MKMapView *)mapView annotationView:(MKAnnotationView *)view calloutAccessoryControlTapped:(UIControl *)control { PlaceDetailView *detailView = [[PlaceDetailView alloc] initWithStyle:UITableViewStyleGrouped]; detailView.place = [view.annotation place]; [self.navigationController pushViewController:detailView animated:YES]; [detailView release]; } This is working great but i'm having the following issues: If i try and access the place getter method like so view.annotation.place i recieve an error: Accessing unknown place getter method If i acces the place getter method like so [view.annotation place] i receive a warning: place not found in protocol From my understanding this is because the place object is not defined in the MKAnnotation protocol, although i'm aware of this i'm not sure how to tell the complier that place does exist and it's not calling it blind.

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  • Storing tree data in Javascript

    - by Ozh
    I need to store data to represent this: Water + Fire = Steam Water + Earth = Mud Mud + Fire = Rock The goal is the following: I have draggable HTML divs, and when <div id="Fire"> and <div id="Mud"> overlap, I add <div id="Rock"> to the screen. Ever played Alchemy on iPhone or Android? Same stuff Right now, the way I'm doing this is a JS object : var stuff = { 'Steam' : { needs: [ 'Water', 'Fire'] }, 'Mud' : { needs: [ 'Water', 'Earth'] }, 'Rock' : { needs: [ 'Mud', 'Fire'] }, // etc... }; and every time a div overlaps with another one, I traverse the object keys and check the 'needs' array. I can deal with that structure but I was wondering if I could do any better? Edit: I should add that I also need to store a few other things, like a short description or an icon name. So typicall I have Steam: { needs: [ array ], desc: "short desc", icon:"steam.png"},

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