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  • Checking lazy loaded properties have been instantiated

    - by PaulG
    In a class which has a lazy loaded property, such as: private Collection<int> someInts; public Collection<int> SomeInts { get { if (this.someInts == null) this.someInts = new Collection<int>(); return this.someInts; } } Is it worth also having a property such as: public bool SomeIntsExist { get { return (this.someInts != null && this.someInts.Count > 0); } } And then using that property.. eg: if (thatClass.SomeIntsExist) { // do something with thatClass.SomeInts collection } or is this premature optimisation. Its certainly easier to roll with something like below, but it will instantiate the collection needlessly: if (thatClass.SomeInts.Count > 0) { // do something with thatClass.SomeInts collection } Is the compiler smart enough to figure things like this out? Is there a better way?

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  • Binding Navigation Property with Entity Framework

    - by JSmaga
    Hi, I have another question about binding using C# and the entity framework. Here, I'm looking to bind a navigation property to a listbox or a listview. I saw on different posts that if I update the collection using code behind the list would not be notified because the collection does not handle notification (it's always the same problem anyway). People suggested to use an ObservableCollection for example, but, and here is my question, this comes down to basically duplicate the collection and hence, if I modify it, I'd have to handle in code-behind the fact that the change has also to be applied to the "original" navigation property right? If that's the case, I was thinking: why not create a custom property called, say, MyObservableNavigationProperty in a partial class. I could then interact only with this collection, catch the event when the collection is changed and apply the change to the "original" collection. Is that a nice way to do the trick? or am I getting all confused here....

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  • jQuery Running a function in a context and adding to a variable

    - by Mark
    For this question I'm going to give a simplified example of what I want to do, and the function I want to learn to write. var collection = ''; <div id='container'> <span>1</span> <span>2</span> <span>3</span> </div> What I want to do this, for every span in the div, take its text, add it to the collection. So ideally it would look like: $('#container').addtoCollection(collection); The method would be something like: $(this).find('span').each(function () { collection = collection + $(this).text(); }). Where the first this would equal #container. So in the end you can do: console.log(collection); and get: 123 How do I write the function that does this? Thanks!

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  • Marionette js itemview not defined: then on browser refresh it is defined and all works well - race condition?

    - by Robert
    Yeah it's just the initial browser load or two after a cache clear. Subsequent refreshes clear the problem up. I'm thinking the item views just aren't fully constructed in time to be used in the collection views on the first load. But then they are on a refresh? Don't know. There must be something about the code sequence or loading or the load time itself. Not sure. I'm loading via require.js. Have two collections - users and messages. Each renders in its own list view. Each works, just not the first time or two the browser loads. The first time you load after clearing browser cache the console reports, for instance: "Uncaught ReferenceError: MessageItemView is not defined" A simple browser refresh clears it up. Same goes for the user collection. It's collection view says it doesn't know anything about its item view. But a simple browser refresh and all is well. My views (item and collection) are in separate files. Is that the problem? For instance, here is my message collection view in its own file: messagelistview.js var MessageListView = Marionette.CollectionView.extend({ itemView: MessageItemView, el: $("#messages") }); And the message item view is in a separate file: messageview.js var MessageItemView = Marionette.ItemView.extend({ tagName: "div", template: Handlebars.compile( '<div>{{fromUserName}}:</div>' + '<div>{{message}}</div>' + ) }); Then in my main module file, which references each of those files, the collection view is constructed and displayed: main.js //Define a model MessageModel = Backbone.Model.extend(); //Make an instance of MessageItemView - code in separate file, messagelistview.js MessageView = new MessageItemView(); //Define a message collection var MessageCollection = Backbone.Collection.extend({ model: MessageModel }); //Make an instance of MessageCollection var collMessages = new MessageCollection(); //Make an instance of a MessageListView - code in separate file, messagelistview.js var messageListView = new MessageListView({ collection: collMessages }); App.messageListRegion.show(messageListView); Do I just have things sequenced wrong? I'm thinking it's some kind of race condition only because over 3G to an iPad the item views are always undefined. They never seem to get constructed in time. PC on a hard wired connection does see success after a browser refresh or two.

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  • backbonejs remove anomaly concept

    - by user1537158
    I was building a small app for adding and deleting li from ul using Backbonejs.One of the SO members cymen helped me code it, using that i tailored the code a little.currently if i add one element and delete , it works , but the second time i add an element (to ul) and go to delete it , i get Uncaught TypeError: Cannot call method 'remove' of undefined Pasting my code here , HTML : <input type="text" id="name"> <button id="add">Add</button> <ul id="mylist"></ul> JS: $(function(){ var myCollection = Backbone.Collection.extend(); var myView = Backbone.View.extend({ el:$('body'), tagName:'li', initialize : function(e){ this.collection.bind("add",this.render,this); this.collection.bind("remove",this.render,this); }, events:{ 'click #add' : 'addfoo' }, addfoo : function(){ var myname= $('#name').val(); $('#name').val(''); this.collection.add({name:myname}); }, render : function(){ $('#mylist').empty(); this.collection.each(function(model){ console.log("myView"); var remove = new myRemoveView({model:model}); remove.render(); }); } }); var myRemoveView = Backbone.View.extend({ el:$('body'), events:{ 'click .button':'removeFoo' }, removeFoo : function(){ console.log("here"); this.model.collection.remove(this.model); }, render : function(){ console.log("second view"); $('#mylist').append('<li>'+this.model.get('name') + "<button class='button'>"+"delete"+"</button></li>"); return; } }); var view = new myView({collection: new myCollection()}); }); Two things i did not understand : i) in the removeFoo function , we write this.model.collection.remove(this.model) shouldnt this have been this.collection.model.remove , something of that sort ? ii) i add a li to ul , then i delete it , when i add another li (appending to ul works perfect) but this time when i go to delete it throws me the above error : Uncaught TypeError :cannot call method 'remove' of undefined can you please help me figure out these 2 doubts in my code , btw SO member cymen's code works like a charm only my tailored code (above) is giving me errors. SO member cymen's code : JS Fiddle for his code Thank you

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  • best way to pick a random subset from a collection?

    - by Tom
    I have a set of objects in a Vector from which I'd like to select a random subset (e.g. 100 items coming back; pick 5 randomly). In my first (very hasty) pass I did an extremely simple and perhaps overly clever solution: Vector itemsVector = getItems(); Collections.shuffle(itemsVector); itemsVector.setSize(5); While this has the advantage of being nice and simple, I suspect it's not going to scale very well, i.e. Collections.shuffle() must be O(n) at least. My less clever alternative is Vector itemsVector = getItems(); Random rand = new Random(System.currentTimeMillis()); // would make this static to the class List subsetList = new ArrayList(5); for (int i = 0; i < 5; i++) { // be sure to use Vector.remove() or you may get the same item twice subsetList.add(itemsVector.remove(rand.nextInt(itemsVector.size()))); } Any suggestions on better ways to draw out a random subset from a Collection?

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  • Can't operator == be applied to generic types in C#?

    - by Hosam Aly
    According to the documentation of the == operator in MSDN, For predefined value types, the equality operator (==) returns true if the values of its operands are equal, false otherwise. For reference types other than string, == returns true if its two operands refer to the same object. For the string type, == compares the values of the strings. User-defined value types can overload the == operator (see operator). So can user-defined reference types, although by default == behaves as described above for both predefined and user-defined reference types. So why does this code snippet fail to compile? void Compare<T>(T x, T y) { return x == y; } I get the error Operator '==' cannot be applied to operands of type 'T' and 'T'. I wonder why, since as far as I understand the == operator is predefined for all types? Edit: Thanks everybody. I didn't notice at first that the statement was about reference types only. I also thought that bit-by-bit comparison is provided for all value types, which I now know is not correct. But, in case I'm using a reference type, would the the == operator use the predefined reference comparison, or would it use the overloaded version of the operator if a type defined one? Edit 2: Through trial and error, we learned that the == operator will use the predefined reference comparison when using an unrestricted generic type. Actually, the compiler will use the best method it can find for the restricted type argument, but will look no further. For example, the code below will always print true, even when Test.test<B>(new B(), new B()) is called: class A { public static bool operator==(A x, A y) { return true; } } class B : A { public static bool operator==(B x, B y) { return false; } } class Test { void test<T>(T a, T b) where T : A { Console.WriteLine(a == b); } }

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  • How do I get the collection of Model State Errors in ASP.NET MVC?

    - by Ryan Montgomery
    How do I get the collection of errors in a view? I don't want to use the Html Helper Validation Summary or Validation Message. Instead I want to check for errors and if any display them in specific format. Also on the input controls I want to check for a specific property error and add a class to the input. P.S. I'm using the Spark View Engine but the idea should be the same. So I figured I could do something like... <if condition="${ModelState.Errors.Count > 0}"> DispalyErrorSummary() </if> ....and also... <input type="text" value="${Model.Name}" class="?{ModelState.Errors["Name"] != string.empty} error" /> .... Or something like that. UPDATE My final solution looked like this: <input type="text" value="${ViewData.Model.Name}" class="text error?{!ViewData.ModelState.IsValid && ViewData.ModelState["Name"].Errors.Count() > 0}" id="Name" name="Name" /> This only adds the error css class if this property has an error.

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  • Criteria API - How to get records based on collection count?

    - by Cosmo
    Hello Guys! I have a Question class in ActiveRecord with following fields: [ActiveRecord("`Question`")] public class Question : ObcykaniDb<Question> { private long id; private IList<Question> relatedQuestions; [PrimaryKey("`Id`")] private long Id { get { return this.id; } set { this.id = value; } } [HasAndBelongsToMany(typeof(Question), ColumnRef = "ChildId", ColumnKey = "ParentId", Table = "RelatedQuestion")] private IList<Question> RelatedQuestions { get { return this.relatedQuestions; } set { this.relatedQuestions = value; } } } How do I write a DetachedCriteria query to get all Questions that have at least 5 related questions (count) in the RelatedQuestions collection? For now this gives me strange results: DetachedCriteria dCriteria = DetachedCriteria.For<Question>() .CreateCriteria("RelatedQuestions") .SetProjection(Projections.Count("Id")) .Add(Restrictions.EqProperty(Projections.Id(), "alias.Id")); DetachedCriteria dc = DetachedCriteria.For<Question>("alias").Add(Subqueries.Le(5, dCriteria)); IList<Question> results = Question.FindAll(dc); Any ideas what I'm doing wrong?

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  • how to implement class with collection of string/object pairs so that an object can be returned with

    - by matti
    The values in a file are read as string and can be double, string or int or maybe even lists. An example file: DatabaseName=SomeBase Classes=11;12;13 IntValue=3 //this is required! DoubleValue=4.0 I was thinking something like this: public static T GetConfigValue(string cfgName) { // here we just return for example the value which could // be List[int] if parameter cfgName='Classes' // and LoadConfig was called with Dictionary containing // keyvaluepair 'Classes' / typeof(List[int]) } public static bool LoadConfig(Dictionary reqSettings, Dictionary optSettings) { foreach (KeyValuePair kvPair in reqSettings) { if (ReadCheckAndStore(kVPair, true)) return false; } foreach (KeyValuePair kvPair in reqSettings) { if (ReadCheckAndStore(kVPair, false)) return false; } return true; } private static bool ReadCheckAndStore(KeyValuePair kVPair, bool isRequired) { if (!ReadValue(kVPair.Key, out confValue) && isRequired) //req. IntValue !found return false; //here also have to test if read value is wanted type. //and if yes store to collection. } Thanks a lot & BR! -Matti PS. Additional issue is default values for optional settings. It's not elegant to pass them to LoadConfig in separate Dictionary, but that is an other issue...

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  • How to add validation errors in the validation collection asp.net mvc?

    - by johndoe
    Inside my controller's action I have the following code: public ActionResult GridAction(string id) { if (String.IsNullOrEmpty(id)) { // add errors to the errors collection and then return the view saying that you cannot select the dropdownlist value with the "Please Select" option } return View(); UPDATE: if (String.IsNullOrEmpty(id)) { // add error ModelState.AddModelError("GridActionDropDownList", "Please select an option"); return RedirectToAction("Orders"); } } UPDATE 2: Here is my updated code: @Html.DropDownListFor(x => x.SelectedGridAction, Model.GridActions,"Please Select") @Html.ValidationMessageFor(x => x.SelectedGridAction) The Model looks like the following: public class MyInvoicesViewModel { private List<SelectListItem> _gridActions; public int CurrentGridAction { get; set; } [Required(ErrorMessage = "Please select an option")] public string SelectedGridAction { get; set; } public List<SelectListItem> GridActions { get { _gridActions = new List<SelectListItem>(); _gridActions.Add(new SelectListItem() { Text = "Export to Excel", Value = "1"}); return _gridActions; } } } And here is my controller action: public ActionResult GridAction(string id) { if (String.IsNullOrEmpty(id)) { // add error ModelState.AddModelError("SelectedGridAction", "Please select an option"); return RedirectToAction("Orders"); } return View(); } Nothing happens! I am totally lost on this one! UPDATE 3: I am now using the following code but still the validation is not firing: public ActionResult GridAction(string id) { var myViewModel= new MyViewModel(); myViewModel.SelectedGridAction = id; // id is passed as null if (!ModelState.IsValid) { return View("Orders"); }

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  • How can i use complextype class or multi type class is it generic collection?

    - by programmerist
    i need a complex returning type. i have 4 class returning types COMPLEXTYPE must include Company, Muayene, Radyoloji, Satis because i must return data switch case situation how can i do? Maybe i need generic collections How can i do that? public class GenoTipController { public COMPLEXTYPE Generate(DataModelType modeltype) { _Company company = null; _Muayene muayene = null; _Radyoloji radyoloji = null; _Satis satis = null; switch (modeltype) { case DataModelType.Radyoloji: radyoloji = new Radyoloji(); return radyoloji; break; case DataModelType.Satis: satis = new Satis(); return satis; break; case DataModelType.Muayene: muayene = new Muayene(); return muayene; break; case DataModelType.Company: company = new Company(); return company; break; default: break; } } } public class CompanyView { public static List GetPersonel() { GenoTipController controller = new GenoTipController(); _Company company = controller.Generate(DataModelType.Company); return company.GetPersonel(); } } public enum DataModelType { Radyoloji, Satis, Muayene, Company }

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  • Converting Generic Type into reference type after checking its type using GetType(). How ?

    - by Shantanu Gupta
    i am trying to call a function that is defined in a class RFIDeas_Wrapper(dll being used). But when i checked for type of reader and after that i used it to call function it shows me error Cannot convert type T to RFIDeas_Wrapper. EDIT private List<string> GetTagCollection<T>(T Reader) { TagCollection = new List<string>(); if (Reader.GetType() == typeof(RFIDeas_Wrapper)) { ((RFIDeas_Wrapper)Reader).OpenDevice(); // here Reader is of type RFIDeas_Wrapper //, but i m not able to convert Reader into its datatype. string Tag_Id = ((RFIDeas_Wrapper)Reader).TagID(); //Adds Valid Tag Ids into the collection if(Tag_Id!="0") TagCollection.Add(Tag_Id); } else if (Reader.GetType() == typeof(AlienReader)) TagCollection = ((AlienReader)Reader).TagCollection; return TagCollection; } ((RFIDeas_Wrapper)Reader).OpenDevice(); , ((AlienReader)Reader).TagCollection; I want this line to be executed without any issue. As Reader will always be of the type i m specifying. How to make compiler understand the same thing.

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  • How am I able to create A List<T> containing a generic Interface?

    - by Conrad Clark
    I have a List which must contain IInteract Objects. But IInteract is a generic interface which requires 2 type arguments. My main idea is iterate through a list of Objects and "Interact" one with another if they didn't interact yet. So i have this object List<IObject> WorldObjects = new List<IObject>(); and this one: private List<IInteract> = new List<IInteract>(); Except I can't compile the last line because IInteract requires 2 type arguments. But I don't know what the arguments are until I add them. I could add interactions between Objects of Type A and A... or Objects of Type B and C. I want to create "Interaction" classes which do something with the "acting" object and the "target" object, but I want them to be independent from the objects... so I could add an Interaction between for instance... "SuperUltraClass" and... an "integer". Am I using the wrong approach?

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  • ASP.NET error on Bitmap.Save "Exception (0x80004005): A generic error occurred in GDI+."

    - by Batu
    Hi, I have a function which first reads an image from disk, resizes it and then saves to another directory. when i use the Bitmap.Save(directory + theimagename) it returns the error as i stated in the question title. i checked the directory is right, and the given image name doesn't exist in that dir. what is weird, is that the same code works great on the local machine. but when i upload it to my shared server. it just doesn't work. the code is below. bmpOut = new Bitmap(Size, Size); Graphics g = Graphics.FromImage(bmpOut); g.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.HighQualityBicubic; g.FillRectangle(Brushes.White, 0, 0, Size, Size); int topBottomPadding = 0; int leftRightPadding = 0; if (Size > lnNewWidth + 1) leftRightPadding = Convert.ToInt32((Size - lnNewWidth) / 2); else if (Size > lnNewHeight + 1) topBottomPadding = Convert.ToInt32((Size - lnNewHeight) / 2); g.DrawImage(loBMP, leftRightPadding, topBottomPadding, lnNewWidth, lnNewHeight); Bitmap bmp = new Bitmap(bmpOut); if (bmp != null) bmp.Save(ResizedOutput); bmp.Dispose(); bmpOut.Dispose(); g.Dispose(); loBMP.Dispose(); stack trace: [ExternalException (0x80004005): A generic error occurred in GDI+.] System.Drawing.Image.Save(String filename, ImageCodecInfo encoder, EncoderParameters encoderParams) +377630 System.Drawing.Image.Save(String filename, ImageFormat format) +69 System.Drawing.Image.Save(String filename) +25 Utilities.ResizeImage(String fileName, String mode) in c:\inetpub\vhosts\batuhanakcay.com\httpdocs\App_Code\Utilities.cs:181 Link.ToProductImage(String fileName) in c:\inetpub\vhosts\batuhanakcay.com\httpdocs\App_Code\Link.cs:79 Product.PopulateControls(ProductDetails pd) in c:\inetpub\vhosts\batuhanakcay.com\httpdocs\Product.aspx.cs:37 Product.Page_Load(Object sender, EventArgs e) in c:\inetpub\vhosts\batuhanakcay.com\httpdocs\Product.aspx.cs:20

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  • Can't access resource from Generic.xaml within the Custom Control constructor.

    - by myermian
    I'm not sure why this is doing this, but I can't access the resource from within my constructor. XTabItem.cs using System; using System.ComponentModel; using System.Windows; using System.Windows.Controls; using System.Windows.Media; namespace MyStuff { public class XTabItem : TabItem { public static readonly DependencyProperty XTabItemNormalBackgroundProperty; /// <summary> /// Visual Property: Normal Background /// </summary> [Description("Determines the visibility of the close button."), Category("XTabItem Visual")] public Brush XTabItemNormalBackground { get { return (Brush)GetValue(XTabItemNormalBackgroundProperty); } set { SetValue(XTabItemNormalBackgroundProperty, value); } } static XTabItem() { DefaultStyleKeyProperty.OverrideMetadata(typeof(XTabItem), new FrameworkPropertyMetadata(typeof(XTabItem))); XTabItemNormalBackgroundProperty = DependencyProperty.Register("XTabItemNormalBackground", typeof(Brush), typeof(XTabItem), new UIPropertyMetadata(null)); } public XTabItem() { //XTabItemNormalBackground = (Brush)this.TryFindResource("XTabItemNormalBackgroundBrush"); //THIS DOES NOT WORK?? } public override void OnApplyTemplate() { base.OnApplyTemplate(); } } } Generic.xaml <ResourceDictionary xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:local="clr-namespace:MyStuff" xmlns:con="clr-namespace:MyStuff.Converters" > <SolidColorBrush x:Key="XTabItemNormalBackgroundBrush" Color="BlueViolet" /> <Style TargetType="{x:Type local:XTabItem}"> <Setter Property="Template"> <Setter.Value> <ControlTemplate TargetType="{x:Type local:XTabItem}"> <!-- CONTENT TEMPLATE --> <Grid SnapsToDevicePixels="True"> <Border x:Name="_Border" Background="{Binding Path=XTabItemNormalBackground, RelativeSource={RelativeSource Mode=TemplatedParent}}" BorderBrush="{TemplateBinding BorderBrush}" BorderThickness="1,1,1,0"> ... </Border> </Grid> </Style> </ResourceDictionary>

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  • HTML converted to jQuery collection not searchable with selectors?

    - by jimp
    I am trying to dynamically load a page using $.get(), parse the return with var $content = $(data), and ultimately use selectors to find only certain parts of the document. Only I cannot figure out why the jQuery collection returned from $(data) does not find some very basic selectors. I set up a jsFiddle to illustrate the problem using a very small string of HTML. <html> <head> <title>See Our Events</title> </head> <body><div id="content">testing</div></body> </html> I want to find the <title> node. var html = "<html>\n"+ "<head>\n"+ " <title>See Our Events</title>\n"+ "</head>\n"+ "<body><div id=\"content\">testing</div></body>\n"+ "</html>"; var $content = $(html); console.log($content.find('title').length); // Logs 0. Why? If I wrap a <div> around the HTML, then the selector works. (But if you look at the jsFiddle, other variations of the selector still do not work!) var html = "<div><html>\n"+ "<head>\n"+ " <title>See Our Events</title>\n"+ "</head>\n"+ "<body><div id=\"content\">testing</div></body>\n"+ "</html></div>"; var $content = $(html); console.log($content.find('title').length); // Logs 1. Please look at the jsFiddle, too. It contains more examples than my code here to keep the post easier to read. Why does my otherwise very basic selector not return the title node?

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  • Is there a generic way of dealing with varying connection strings in C#?

    - by James Wiseman
    I have an application that needs to connect to a SQL database, and execute a SQL Agent Job. The connection string I am trying to access is stored in the registry, which is easily enough pulled out. This appliction is to be run on multiple computers, and I cannot guarantee the format of this connection string being consistent across these computers. Two that I have pulled out for example are: Data Source=Server1;Initial Catalog=DB1;Integrated Security=SSPI; Data Source=Server2;Initial Catalog=DB1;Provider=SQLNCLI.1;Integrated Security=SSPI;Auto Translate=False; I can use an object of type System.Data.SqlClient.SqlConnection to connect to the database with the first connection string, howevever, I get the following error when I pass the second to it: keyword not supported: 'provider' Similarly, I can use the an object of type System.Data.OleDb.OleDbConnection to connect to the database with the second connection string, howevever, I get the following error when I pass the first to it: An OLEDB Provider was not specified in the ConnectionString' I can solve this by scanning the string for 'Provider' and doing the connect conditionally, however I can't help but feel that there is a better way of doing this, and handle the connection strings in a more generic fashion. Does anyone have any suggestions?

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  • Java: how do I get a class literal from a generic type?

    - by Tom
    Typically, I've seen people use the class literal like this: Class<Foo> cls = Foo.class; But what if the type is generic, e.g. List? This works fine, but has a warning since List should be parameterized: Class<List> cls = List.class So why not add a <?>? Well, this causes a type mismatch error: Class<List<?>> cls = List.class I figured something like this would work, but this is just a plain ol' a syntax error: Class<List<Foo>> cls = List<Foo>.class How can I get a Class<List<Foo>> statically, e.g. using the class literal? I could use @SuppressWarnings("unchecked") to get rid of the warnings caused by the non-parameterized use of List in the first example, Class<List> cls = List.class, but I'd rather not. Any suggestions? Thanks!

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  • Initial capacity of collection types, i.e. Dictionary, List

    - by Neil N
    Certain collection types in .Net have an optional "Initial Capacity" constructor param. i.e. Dictionary<string, string> something = new Dictionary<string,string>(20); List<string> anything = new List<string>(50); I can't seem to find what the default initial capacity is for these objects on MSDN. If I know I will only be storing 12 or so items in a dictionary, doesn't it make sense to set the initial capacity to something like 20? My reasoning is, assuming the capacity grows like it does for a StringBuiler, which doubles each time the capacity is hit, and each re-allocation is costly, why not pre-set the size to something you know will hold your data, with some extra room just in case? If the initial capacity is 100, and I know I will only need a dozen or so, it seems as though the rest of that allocated RAM is allocated for nothing. Please spare me the "premature optimization" speil for the O(n^n)th time. I know it won't make my apps any faster or save any meaningful amount of memory, this is mostly out of curiosity.

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  • How can I build a generic dataset-handling Perl library?

    - by Pep.
    Hello, I want to build a generic Perl module for handling and analysing biomedical character separated datasets and which can, most certain, be used on any kind of datasets that contain a mixture of categorical (A,B,C,..) and continuous (1.2,3,881..) and identifier (XXX1,XXX2...). The plan is to have people initialize the module and then use some arguments to point to the data file(s), the place were the analysis reports should be placed and the structure of the data. By structure of data I mean which variable is in which place and its name/type. And this is where I need some enlightenment. I am baffled how to do this in a clean way. Obviously, having people create a simple schema file, be it XML or some other format would be the cleanest but maybe not all people enjoy doing something like this. The solutions I can think of are: Create a configuration file in XML or similar and with a prespecified format. Pass the information during initialization of the module. Use the first row of the data as headers and try to guess types (ouch) Surely there must be a "canonical" way of doing this that is also usable and efficient. Thanks p.

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  • How to use a class's type as the type argument for an inherited collection property in C#

    - by Edelweiss Peimann
    I am trying to create a representation of various types of card that inherit from a generic card class and which all contain references to their owning decks. I tried re-declaring them, as suggested here, but it still won't convert to the specific card type. The code I currently have is as such: public class Deck<T> : List<T> where T : Card { void Shuffle() { throw new NotImplementedException("Shuffle not yet implemented."); } } public class Card { public Deck<Card> OwningDeck { get; set; } } public class FooCard : Card { public Deck<FooCard> OwningDeck { get { return (Deck<FooCard>)base.OwningDeck; } set { OwningDeck = value; } } } The compile-time error I am getting: Error 2 Cannot convert type 'Game.Cards.Deck' to 'Game.Cards.Deck' And a warning suggesting I use a new operator to specify that the hiding is intentional. Would doing so be a violation of convention? Is there a better way? My question to stackoverflow is this: Can what I am trying to do be done elegantly in the .NET type system? If so, can some examples be provided?

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  • VB.NET Two different approaches to generic cross-threaded operations; which is better?

    - by BASnappl
    VB.NET 2010, .NET 4 Hello, I recently read about using SynchronizationContext objects to control the execution thread for some code. I have been using a generic subroutine to handle (possibly) cross-thread calls for things like updating UI controls that utilizes Invoke. I'm an amateur and have a hard time understanding the pros and cons of any particular approach. I am looking for some insight on which approach might be preferable and why. Update: This question is motivated, in part, by statements such as the following from the MSDN page on Control.InvokeRequired. An even better solution is to use the SynchronizationContext returned by SynchronizationContext rather than a control for cross-thread marshaling. Method 1: Public Sub InvokeControl(Of T As Control)(ByVal Control As T, ByVal Action As Action(Of T)) If Control.InvokeRequired Then Control.Invoke(New Action(Of T, Action(Of T))(AddressOf InvokeControl), New Object() {Control, Action}) Else Action(Control) End If End Sub Method 2: Public Sub UIAction(Of T As Control)(ByVal Control As T, ByVal Action As Action(Of Control)) SyncContext.Send(New Threading.SendOrPostCallback(Sub() Action(Control)), Nothing) End Sub Where SyncContext is a Threading.SynchronizationContext object defined in the constructor of my UI form: Public Sub New() InitializeComponent() SyncContext = WindowsFormsSynchronizationContext.Current End Sub Then, if I wanted to update a control (e.g., Label1) on the UI form, I would do: InvokeControl(Label1, Sub(x) x.Text = "hello") or UIAction(Label1, Sub(x) x.Text = "hello") So, what do y'all think? Is one way preferred or does it depend on the context? If you have the time, verbosity would be appreciated! Thanks in advance, Brian

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  • best practices question: How to save a collection of images and a java object in a single file? File

    - by Richard
    Hi all, I am making a java program that has a collection of flash-card like objects. I store the objects in a jtree composed of defaultmutabletreenodes. Each node has a user object attached to it with has a few string/native data type parameters. However, i also want each of these objects to have an image (typical formats, jpg, png etc). I would like to be able to store all of this information, including the images and the tree data to the disk in a single file so the file can be transferred between users and the entire tree, including the images and parameters for each object, can be reconstructed. I had not approached a problem like this before so I was not sure what the best practices were. I found XLMEncoder (http://java.sun.com/j2se/1.4.2/docs/api/java/beans/XMLEncoder.html) to be a very effective way of storing my tree and the native data type information. However I couldn't figure out how to save the image data itself inside of the XML file, and I'm not sure it is possible since the data is binary (so restricted characters would be invalid). My next thought was to associate a hash string instead of an image within each user object, and then gzip together all of the images, with the hash strings as the names and the XMLencoded tree in the same compmressed file. That seemed really contrived though. Does anyone know a good approach for this type of issue? THanks! Thanks!

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  • Generic that takes only numeric types (int double etc)?

    - by brandon
    In a program I'm working on, I need to write a function to take any numeric type (int, short, long etc) and shove it in to a byte array at a specific offset. There exists a Bitconverter.GetBytes() method that takes the numeric type and returns it as a byte array, and this method only takes numeric types. So far I have: private void AddToByteArray<T>(byte[] destination, int offset, T toAdd) where T : struct { Buffer.BlockCopy(BitConverter.GetBytes(toAdd), 0, destination, offset, sizeof(toAdd)); } So basically my goal is that, for example, a call to AddToByteArray(array, 3, (short)10) would take 10 and store it in the 4th slot of array. The explicit cast exists because I know exactly how many bytes I want it to take up. There are cases where I would want a number that is small enough to be a short to really take up 4 bytes. On the flip side, there are times when I want an int to be crunched down to just a single byte. I'm doing this to create a custom network packet, if that makes any ideas pop in to your heads. If the where clause of a generic supported something like "where T : int || long || etc" I would be ok. (And no need to explain why they don't support that, the reason is fairly obvious) Any help would be greatly appreciated! Edit: I realize that I could just do a bunch of overloads, one for each type I want to support... but I'm asking this question because I want to avoid precisely that :)

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