Search Results

Search found 53463 results on 2139 pages for 'net generics'.

Page 420/2139 | < Previous Page | 416 417 418 419 420 421 422 423 424 425 426 427  | Next Page >

  • Why can't I enforce derived classes to have parameterless constructors?

    - by FrisbeeBen
    I am trying to do the following: public class foo<T> where T : bar, new() { public foo() { _t = new T(); } private T _t; } public abstract class bar { public abstract void someMethod(); // Some implementation } public class baz : bar { public overide someMethod(){//Implementation} } And I am attempting to use it as follows: foo<baz> fooObject = new foo<baz>(); And I get an error explaining that 'T' must be a non-abstract type with a public parameterless constructor in order to use it as parameter 'T' in the generic type or method. I fully understand why this must be, and also understand that I could pass a pre-initialized object of type 'T' in as a constructor argument to avoid having to 'new' it, but is there any way around this? any way to enforce classes that derive from 'bar' to supply parameterless constructors?

    Read the article

  • A strange error in java generic.

    - by ???
    This is ok: Class<? extends String> stringClass = "a".getClass(); But this gets error: <T> void f(T obj) { Class<? extends T> objClass = obj.getClass(); } I know I can cast it like: <T> void f(T obj) { @SuppressWarnings("unchecked") Class<? extends T> objClass = (Class<? extends T>) obj.getClass(); } But why the previous error? Will the next release of Java 7 will support such usage?

    Read the article

  • Generic Func<> as parameter to base method

    - by WestDiscGolf
    I might be losing the plot, but I hope someone can point me in the right direction. What am I trying to do? I'm trying to write some base methods which take Func< and Action so that these methods handle all of the exception handling etc. so its not repeated all over the place but allow the derived classes to specify what actions it wants to execute. So far this is the base class. public abstract class ServiceBase<T> { protected T Settings { get; set; } protected ServiceBase(T setting) { Settings = setting; } public void ExecAction(Action action) { try { action(); } catch (Exception exception) { throw new Exception(exception.Message); } } public TResult ExecFunc<T1, T2, T3, TResult>(Func<T1, T2, T3, TResult> function) { try { /* what goes here?! */ } catch (Exception exception) { throw new Exception(exception.Message); } } } I want to execute an Action in the following way in the derived class (this seems to work): public void Delete(string application, string key) { ExecAction(() => Settings.Delete(application, key)); } And I want to execute a Func in a similar way in the derived class but for the life of me I can't seem to workout what to put in the base class. I want to be able to call it in the following way (if possible): public object Get(string application, string key, int? expiration) { return ExecFunc(() => Settings.Get(application, key, expiration)); } Am I thinking too crazy or is this possible? Thanks in advance for all the help.

    Read the article

  • Raise differing beeps

    - by themaninthesuitcase
    I need to be able to raise different types of audio notifications to the user. I need an "ok" and an "error" type sounds, I was hoping to be able to raise a simple beep and a critical stop type sound but I can only find the Beep() command which doesn't allow for differing sounds. Is there a library that does what I need or will I need to roll my own using the system wavs.

    Read the article

  • Generic factory of generic containers

    - by Feuermurmel
    I have a generic abstract class Factory<T> with a method createBoxedInstance() which returns instances of T created by implementations of createInstance() wrapped in the generic container Box<T>. abstract class Factory<T> { abstract T createInstance(); public final Box<T> createBoxedInstance() { return new Box<T>(createInstance()); } public final class Box<T> { public final T content; public Box(T content) { this.content = content; } } } At some points I need a container of type Box<S> where S is an ancestor of T. Is it possible to make createBoxedInstance() itself generic so that it will return instances of Box<S> where S is chosen by the caller? Sadly, defining the function as follows does not work as a type parameter cannot be declared using the super keyword, only used. public final <S super T> Box<S> createBoxedInstance() { return new Box<S>(createInstance()); } The only alternative I see, is to make all places that need an instance of Box<S> accept Box<? extends S> which makes the container's content member assignable to S. Is there some way around this without re-boxing the instances of T into containers of type Box<S>? (I know I could just cast the Box<T> to a Box<S> but I would feel very, very guilty.)

    Read the article

  • How to check if TypeIdenitifier(T) is an Object?

    - by John
    I'm creating a generic list class that has a member of type Array(Array of ). The problem is the class descruction,because the class is supposed to be used for types from byte to types inheriting TObject. Specifically: destructor Destroy; var elem:T; begin /*if(T is Tobject) then //Check if T inherits TObject {Compiler error!} for elem in FData do TObject(elem).Free;*/ // do not know how to do it SetLength(FItems,0); //FItems : Array of T inherited Destroy; end; How do I check if T is TObject so I can free every member if the typeidenitifier is a class,for example?

    Read the article

  • Common type for generic classes of different types

    - by DinGODzilla
    I have (for example) Dictionary of different generic types (d1, d2, d3, d4) and I want to store them in something var d1 = new Dictionary<int, string>(); var d2 = new Dictionary<int, long>(); var d3 = new Dictionary<DateTime, bool>(); var d4 = new Dictionary<string, object>(); var something = ??? //new List<object> {d1, d2, d3, d4}; Is there any other way how to store that in something with common denominator different than object? Thanks :-)

    Read the article

  • [C#] How do I make hierarchy of objects from two alternating classes?

    - by Millicent
    Here's the scenario: I have two classes ("Page" and "Field"), that are descended from a common class ("Pield"). They represent tags in an XML file and are in the following hierarchy: <page> <field> <page> ... </page> ... </field> ... </page> I.e.: Page and Field objects are in a hierarchy of alternating type (there may be more than one Page or Field to each rung of the hierarchy). Every Field and Page object has a parent property, which points to the respective parent object of the other type. This is not a problem unless the parent-child mechanism is controlled by the base class (Pield), which is shared by the two descended classes (Page and Field). Here is one try, that fails at the line "Pield child = new Pield(pchild, this);": class Pield<T> { private T _pield_parent; ... private void get_children() { ... Pield<Page> child = new Pield<Page>(pchild, this); ... } ... } class Page : Pield<Field> { ... } class Field : Pield<Page> { ... } Any ideas about how to solve this elegantly? Best, Millicent

    Read the article

  • Choose between multiple options with defined probability

    - by Sijin
    I have a scenario where I need to show a different page to a user for the same url based on a probability distribution, so for e.g. for 3 pages the distribution might be page 1 - 30% of all users page 2 - 50% of all users page 3 - 20% of all users When deciding what page to load for a given user, what technique can I use to ensure that the overall distribution matches the above? I am thinking I need a way to choose an object at "random" from a set X { x1, x2....xn } except that instead of all objects being equally likely the probability of an object being selected is defined beforehand.

    Read the article

  • Passing derived objects in a constructure

    - by Clarence Klopfstein
    This is a bit of a convoluted question, hopefully I can make it clear. I am finding that this may not be possible, but am trying to see if anybody has a solution. I have four classes, two are core classes and two are those core classes extended: extUser Extends coreUser extSecurity Extends coreSecurity In the constructor for coreUser you have this: public coreUser(string id, ref coreSecurity cs) When trying to extend coreUser you would have this: public extUser(string id ref extSecurity es) : base(id, ref es) This fails because es is of type, extSecurity and the base class expects a type of coreSecurity. I've not found anyway to cast this to allow for me to override this base class in C#. In VB it works just fine. Ideas?

    Read the article

  • How to outsource pieces of a web project

    - by Luke101
    I would like to outsource pieces of a new web application/site. I don't want one company working on the whole project because they can easily change a few things and sell the software to someone else. I will be using a freelenace website like elance or guru. A buddy of mine has given me this advice but he did not say how this can be done. Any ideas on how to go about this?

    Read the article

  • Select item in CascadingDropDown via JavaScript & invoke update

    - by akosch
    In code-behind I can do this to select something: // Select item in first DropDownList myCascadingDropDown_1.SelectedValue = itemValue_1+":::"+itemText_1; // Select item in second DropDownList myCascadingDropDown_2.SelectedValue = itemValue_2+":::"+itemText_2; How can I do this in JavaScript? (I'm aware, that I could search the list and set the selectedIndex property for each dropdown, but I have many items and i'm very lazy.) EDIT: npups answer works: I can select my desired item in the first dropdownlist. The problem is however, that new values based on that selected item (it is a CascadingDropDown, remember?) don't show in the second dropdown so I can't select anything there. I would need to somehow invoke the update method of the second dropdown manually: any suggestions?

    Read the article

  • How can I convince IE to simply display application/json rather than offer to download it?

    - by Cheeso
    While debugging jQuery apps that use AJAX, I often have the need to see the json that is being returned by the service to the browser. So I'll drop the URL for the JSON data into the address bar. This is nice with ASPNET because in the event of a coding error, I Can see the ASPNET diagostic in the browser: But when the server-side code works correctly and actually returns JSON, IE prompts me to download it, so I can't see the response. Can I get IE to NOT do that, in other words, to just display it as if it were plain text? I know I could do this if I set the Content-Type header to be text/plain. But this is specifically an the context of an ASPNET MVC app, which sets the response automagically when I use JsonResult on one of my action methods. Also I kinda want to keep the appropriate content-type, and not change it just to support debugging efforts.

    Read the article

  • Catch/Raise event on table data update C#

    - by Incognito
    Hi, I have 24/7 service which keeps setup (configuration data) for charging, routing and etc in the Sql Server. Once it is started it loads the data from table using Linq2SQL and use the data through all the application. And we need a solution to update the setup data in the table without restarting the application. So I am interested is it possible to catch/determine that the table was updated so I can refresh the setup data in the application. I mean is it possible to have events which will raise when there is any delete, update or insert on the table. Thank you.

    Read the article

  • Why do we need a private constructor?

    - by isthatacode
    if a class has a private constructor then it cant be instantiated. so, if i dont want my class to be instantiated and still use it, then i can make it static. what is the use of a private constructor ? Also its used in singleton class, except that, is there any othe use ? (Note : The reason i am excuding the singleton case above is because I dont understand why do we need a singleton at all ? when there is a static class availble. You may not answer for my this confusion in the question. )

    Read the article

  • How can i find and take in my local machine any file in remote machine?

    - by programmerist
    i try to write any codes. For example i have 2 machine: A computer, B computer. My local machine A computer. i also have sql data base . with "select * from" i can learn PatientID. ForExample PatientID :123456. But this patient's pictures file in B Computer.Picture File Name is equal to PatientID. B Computer ports is open for me. I can listen B Computer's 51124 port. How can i get Files from B machine via Port(But this files includes pics ). But this is Windows App. But i don't know files path. My program must find it automatically

    Read the article

  • Is there a way to keep track of javascript hits?

    - by user54197
    I am populating a table based on a javascript function. I want to limit the data entered to 2, afterwhich I hide the table. Is there a way to track how many hits the javascript code gets hit? function addNewRow() { $('#displayInjuryTable tr:last').after('<tr><td style="font-size:smaller;" class="name"></td><td style="font-size:smaller;" class="address"></td></tr>'); var $tr = $('#displayInjuryTable tr:last'); var propertyCondition = $('#txtInjuryAddress').val(); $tr.find('.name').text($('#txtInjuryName').val()); if (propertyCondition != "") { $tr.find('.address').text($('#txtInjuryAddress').val() + ', ' + $('#txtInjuryCity').val() + ' ' + $('#txtInjuryState').val() + ' ' + $('#txtInjuryZip').val()); }

    Read the article

  • Extract and replace named group regex

    - by user557670
    I was able to extract href value of anchors in an html string. Now, what I want to achieve is extract the href value and replace this value with a new GUID. I need to return both the replaced html string and list of extracted href value and it's corresponding GUID. Thanks in advance. My existing code is like: Dim sPattern As String = "<a[^>]*href\s*=\s*((\""(?<URL>[^\""]*)\"")|(\'(?<URL>[^\']*)\')|(?<URL>[^\s]* ))" Dim matches As MatchCollection = Regex.Matches(html, sPattern, RegexOptions.IgnoreCase Or RegexOptions.IgnorePatternWhitespace) If Not IsNothing(matches) AndAlso matches.Count > 0 Then Dim urls As List(Of String) = New List(Of String) For Each m As Match In matches urls.Add(m.Groups("URL").Value) Next End If Sample HTML string: <html><body><a title="http://www.google.com" href="http://www.google.com">http://www.google.com</a><br /><a href="http://www.yahoo.com">http://www.yahoo.com</a><br /><a title="http://www.apple.com" href="http://www.apple.com">Apple</a></body></html>

    Read the article

  • Delphi 2010 - Why can't I declare an abstract method with a generic type parameter?

    - by James
    I am trying to do the following in Delphi 2010: TDataConverter = class abstract public function Convert<T>(const AData: T): string; virtual; abstract; end; However, I keep getting the following compiler error: E2533 Virtual, dynamic and message methods cannot have type parameters I don't quite understand the reason why I can't do this. I can do this in C# e.g. public abstract class DataConverter { public abstract string Convert<T>(T data); } Anyone know the reasoning behind this?

    Read the article

  • Deserialize JSON, sometimes value is an array, sometimes "" (blank string).

    - by karl.r
    I am trying to deserialize a field: "presenters":[{...},{...}] but some of the rows come back with only: "presenters":"" When the serializer gets to the row with that empty string I get: Error converting value "" to type 'System.Collections.Generic.List`1[DataPrototype.Model.Presenter]'. Am I right in thinking that I need a JsonConverter that will change the empty string into an empty List?

    Read the article

  • Is it possible in Scala to force the caller to specify a type parameter for a polymorphic method ?

    - by Alex Kravets
    //API class Node class Person extends Node object Finder { def find[T <: Node](name: String): T = doFind(name).asInstanceOf[T] } //Call site (correct) val person = find[Person]("joe") //Call site (dies with a ClassCast inside b/c inferred type is Nothing) val person = find("joe") In the code above the client site "forgot" to specify the type parameter, as the API writer I want that to mean "just return Node". Is there any way to define a generic method (not a class) to achieve this (or equivalent). Note: using a manifest inside the implementation to do the cast if (manifest != scala.reflect.Manifest.Nothing) won't compile ... I have a nagging feeling that some Scala Wizard knows how to use Predef.<:< for this :-) Ideas ?

    Read the article

  • returning a Void object

    - by Robert
    What is the correct way to return a Void type, when it isn't a primitive? Eg. I currently use null as below. interface B<E>{ E method(); } class A implements B<Void>{ public Void method(){ // do something return null; } }

    Read the article

< Previous Page | 416 417 418 419 420 421 422 423 424 425 426 427  | Next Page >