As I try to modernize my C++ skills, I keep encountering this situation where "the STL way" isn't obvious to me. I have an object that wants to gather contributions from multiple sources into a container (typically a std::vector). Each source is an object, and each of those objects provides a method get_contributions() that returns any...
I'm trying to create a new object of type T via its constructor when adding to the list. I'm getting a compile error: The correct error message is: 'T': cannot provide arguments when creating an instance of a variable But it does! Any ideas? public static string GetAllItems<T>(...) where T : new() { ... List<T> tabListItems = ne...
I have a list-generic that has a property (class type). I need a sort method for Z parameters (TrainingSet): public override List<TrainingSet> CalculatedDistancesArray (List<TrainigSet> ts, double x, double y, int k) { for (int i =0; i < ts.Count; i++) { ts[i].Z = (Math.Sqrt(Math.Pow((ts[i].X - x), 2) ...
Just a minor problem with Arraylist. I want to sort a ArrayList<Client> by name. Class Client{ String name; int phonenumber ..} This code does the work, but i'm having a compiler warning: "uses unchecked or unsafe operations". Whats the problem? public void sortByName(){ Collections.sort(ListofClients, new NameComparator()); }...
Normally, I'd choose List<String> [or, in VB, List(Of String)] over StringCollection whenever possible: see also Best string container. However, as it seems, generics — and hence, List<String> — are apparently not supported in VS 2008's settings designer. Therefore, if I want to use a list of strings in my user settings, I have to resor...
Hi! While implementing a design using nested generic collections, I stumbled across those limitations apparently caused by C#'s invariant Generics: Cannot convert from 'Collection<subtype of T> to 'Collection<T>' That means, the following will not work, apparently due to the invariance of Generics: class Outer<TInner, TInnerItem> wh...
Context: .NET 3.5, VS2008. I'm not sure about the title of this question, so feel free to comment about the title, too :-) Here's the scenario: I have several classes, say Foo and Bar, all of them implement the following interface: public interface IStartable { void Start(); void Stop(); } And now I'd like to have a contai...
I'm new to Mac/iPhone programming and Objective-C. In C# and Java we have "generics", collection classes whose members can only be of the type declared. For example, in C# Dictionary<int, MyCustomObject> can only contain keys that are integers and values that are of type MyCustomObject. Does a similar mechanism exist in Objective-C...
I'm attempting to create a generic controller, ie: public class MyController<T> : Controller where T : SomeType { ... } However, when I try to use it, I'm running into this error everywhere... Controller name must end in 'Controller' So, my question, Is it possible to make a generic controller in asp.net mvc? Thanks! ...
Hi, there is an immutable class: Scope<Cmp extends Comparable<Cmp>> public Scope<Cmp> crop(Scope<Cmp> scope) { ... return new Scope<Cmp>(starts, ends); } it has many similar methods is extended by: Timerange extends Scope<Date> and many others (also immutable). Id like them to return object of its type. For example: time...
I'm trying to merge 2 lists using "Union" so I get rid of duplicates. Following is the sample code: public class SomeDetail { public string SomeValue1 { get; set; } public string SomeValue2 { get; set; } public string SomeDate { get; set; } } public class SomeDetailComparer : IEqualityComparer<SomeDetail> { bool IEqual...
Dim classCodeDetails As List(Of ClassCodeDetail) = db.ClassCodeHeaders.Single(Function(cch) cch.CLCH_ID = classCodeHeaderId ).ClassCodeDetails.ToList() classCodeDetails.Sort(Function(c1, c2) c1.Make.MAKE_English.CompareTo(c2.Make.MAKE_English) ) My question is how can I sort on multiple attributes? I want to...
I have the following code, where i am trying to create a generic collection for the objects in my DAL (just an exercise, not actually production code). My problem is that i want to use the type passed in's Read method (which is part of an interface that the classes implement). I cannot create a new T so i dont have an instance of the...
Is it possible to make a method that will take anything, including objects, Integers etc? I have a method checking the value if it is null and I was thinking perhaps it could be done with generics instead of overloading. Unfortunately, trying nullChecking(Class<? extends Object> value){ ... } won't allow Integers as they extend Number...
Is there a method built in to .NET that can write all the properties and such of an object to the console? Could make one using reflection of course, but I'm curious to if this already exists... especially since you can do it in Visual Studio in the Immediate Window. There you can an object name (while in debug mode), press enter, and it...
I've written a simple abstract generic class in C# (.NET 2.0) and I preferably want to limit it to only reference types, so I can indicate no value by a null. However, I also want to use types such as long and decimal, why don't allow null (being structs after all). I considered making the class public abstract Field<Nullable<T>> { ...
EDIT: Page language is VB UPDATE I'm going completely crazy. Here are some screenshots, I hope somebody sees what's going on (TestClass is a simple class with ID and Name property): View (list, model = IEnumerable) View (index, no model) Controller Resulting page at runtime (list: error) Resulting page at runtime (index: works) So...
I have a wrapper generic class that intended to be used with a set of types. Those types are generated by a utility and are all derived from a base class ClientBase. While ClientBase has only a default constructor, all generated types have default constructor as well as a constructor takes a string as parameter. In the constructor of the...
I was doing some performance metrics and I ran into something that seems quite odd to me. I time the following two functions: private static void DoOne() { List<int> A = new List<int>(); for (int i = 0; i < 200; i++) A.Add(i); int s=0; for (int j = 0; j < 100000; j++) { f...
I have code that looks like follows: public interface BaseDAO{ // marker interface } public interface CustomerDAO extends BaseDAO{ public void createCustomer(); public void deleteCustomer(); public Customer getCustomer(int id); // etc } public abstract class DAOFactory { public BaseDAO getCustomerDAO(); public static DAOFactory getIn...