I've been trying to define a generic, inheritable TSingleton class. Here's what I had in progress: TSingleton<RealClass, InheritsFrom : class> = class(InheritsFrom) strict private class var FInstance : RealClass; protected procedure InstanceInitialization;virtual; public destructor Destroy; override; class proced...
I have problem with constraints on generic method. Here is code for all classes: namespace Sdk.BusinessObjects { public interface IBusinessObject { } } namespace Sdk.BusinessObjects { [DataContract] public class AccountDetails : IBusinessObject { [DataMember] public virtual Guid AccountId { get; ...
Why does the following code compile? Why is it allowed to cast a generic list to its type parameter if the parameter is an interface but not a super-interface of the generic? What does this mean? //Connection can be substituted by any interface List<Connection> list = null; Connection c = (Connection) list; ...
I am still experimenting with how Java handles generics. I stumbled upon the fact/issue/thing that if you have a generic interface like A<T>, you cannot really check afterwards if some object is actually implementing A<B> or A<C>. I wondered if that could cause actual problems. Now I have tried this code: static interface A<T> { void ...
You know, like the CLR does. Is anyone even admitting the lack of runtime generic information is a problem, and working to solve it? ...
I'm trying to get the hang of clojure in a selenium2/webdriver project using the webdriver-clj wrapper for webdriver. However, since the webinterface is heavily scripted, I need to have an option to wait until certain elements are created by the script, instead of on page load. So I was trying to create a wait-for function in clojure, ...
Let say I have the following method:: public static int CountNonNullMembers<T>(this IEnumerable<T> enumerable) { if (enumerable == null) throw new ArgumentNullException("enumerable"); int count = 0; foreach (var x in enumerable) { if (x != null) count++; } return count; } And I have these 3 arrays:: v...
I've just came over this article, that suggest various techniques with generics. Author decided to use following: public class BinarySearchTree<T extends Comparable<? super T>> { And I don't get it. Why did author decide to use private Entry<T> root; and not just private Comparable root ? What particular advantage can generic tre...
Okay, to build on my previous question: http://stackoverflow.com/questions/3999761/generically-checking-for-null-that-wont-box-nullables-on-a-non-constrained-type One user suggested putting a constraint for class and for struct and I also implemented the UnboxT pattern of specializing for the three types and storing that logic in delega...
If I use unbounded wildcard types for two collections (each collection will have a different type) as the arguments for a method: private void doAssertion(List<?> testList, List<?> generatedList) Inside this method, can I first check the type of objects in these collections, and then cast the collection to a parameterized type? This j...
In C# it's possible to cast to List<T> - so if you have: List<Activity> _Activities; List<T> _list; The following will work: _list = _Activities as List<T>; but the translated line with VB.NET which is: _list = TryCast(_Activities, List(Of T)) throws a compilation error. So I've had a good hunt around and experimented with LINQ ...
Is there a way to compare two objects that are generic? I'm supposed to find the largest object in a linked list. My first guess was to use the Object's class compareTo method, but I couldn't get that to work. Thanks ...
Given: public class C<T> { private class D { public boolean equals( Object o ) { if ( !(o instanceof D) ) // line 4 return false; D other = (D)o; // line 6 return i == other.i; } int i; } } I get: C.java:4: illegal generic type for inst...
I want to create a simple method that accepts both value type and reference type parameters, i.e. int is value, and string is reference. So this is what I start with: public bool areBothNotNull<T>(T? p1, T? p2) { return (p1.HasValue && p2.HasValue); } So I want to be able to use it like this: var r1 = areBothNotNull<int>(3, 4);...
I have a generic method like this (simplified version): public static TResult PartialInference<T, TResult>(Func<T, TResult> action, object param) { return action((T)param); } In the above, param is of type object on purpose. This is part of the requirement. When I fill in the types, I can call it like this: var test1 = PartialIn...
Hi guys, I have /var/www/cool_codebase on www.example.com AND I have /var/www/cool_codebase on www.example.net The codebases are for the same web app running on different servers. There is some specialisation between the codebases (client-specific bits and bobs etc) - but not too much. One codebase has files that the other doesn't an...
I need to copy a sub set of items from one list to another. However I do not know what kind of items are in the list - or even if the object being passed is a list. I can see if the object is a list by the following code t = DataSource.GetType(); if (t.IsGenericType) { Type elementType = t.GetGenericArguments()[0]; } What I cann...
Hi, I have a question about generics. I have a function that knows about a class type of object that I want to create: public static <T> XmlParserInterface<T> createXmlParser(Class<T> rootType, String currentTagName) { XmlParserInterface<T> result = null; if (rootType.equals(List.class)) { result = new XmlParserList<T>(); } // ...
This is kind of a follow-up from my other question. When I first heard about generics, it was before the release of Delphi 2009 (Where they introduced it first). I know it was supported in .Net before that, but I have yet to dig in that realm. Reading about generics, I learned that it allowed class to have a variable argument to it, an...
Hi all, I would like to have a dictionary that returns a default value when the search key is not found. Reading from the documentation: Generics.Collections.Tdictionary […] This class provides a mapping […] and initial content. 1 - How? Is there a way to do it ala Python: {1: ‘one’; 2:’two’} ? Generics.Collections.TDictionary.TryGet...