extension-methods

Just want to make simple extension for syntactic sygar : public static bool IsNotEmpty(this ICollection obj) { return ((obj != null) && (obj.Count > 0)); } public static bool IsNotEmpty<T>(this ICollection<T> obj) { return ((obj != null) && (obj.Count > 0)); } It works perfectly when I work with some collections, but when working with others I get The call is ambiguous between the following methods or properties: 'PowerOn.ExtensionsBasic.IsNotEmpty(System.Collections.IList)' and 'PowerOn.ExtensionsBasic.IsNotEmpty(System.Collections.Generic.ICollection)' Is there any canonical solution to this

I just gave an answer to a quite simple question by using an extension method. But after writing it down i remembered that you can't unsubscribe a lambda from an event handler. So far no big problem. But how does all this behave within an extension method?? Below is my code snipped again. So can anyone enlighten me, if this will lead to myriads of timers hanging around in memory if you call this extension method multiple times? I would say no, cause the scope of the timer is limited within this function. So after leaving it no one else has a reference to this object. I'm just a little unsure,

Public Class MyList Inherits List(Of MyObject) Public ReadOnly Property SelectedCount() As Integer Get Return Me.Count(Function(obj) obj.IsSelected) End Get End Property End Class The above code causes a compile-time error. As you can see, I'm trying to use extension method Count(<predicate>) . I guess the error is because there is a similarly-named property Count in List class itself too, hiding the extension member. My questions here are: Do I need to explicitly cast my class to something else to access Count extension method? If so, exactly which class should it be in the above scenario?

One interesting aspect of extension methods in .NET is the fact that you can apply them to interfaces. For me, it seems nice that I can define functionality near the interface without defining an abstract class that clutters the assembly. I know that abstract classes are not obsolete or anything, but how do you feel about utilizing this side effect in your code? Example: public static class IUserExtensions { public static bool IsCurrentUser(this IUser user) { return (HttpContext.Current.User != null && HttpContext.Current.User.Identity.Name == user.ID.ToString()); } } public interface IUser {

I'm already familiar with Linq but have little understanding of extension methods I'm hoping someone can help me out. So I have this hierarchical collection pseudo code ie: class Product prop name prop type prop id prop List<Product> children And I have a list of products List products. Is there any way I can look for product in this collection by the id with a extension method ? In other words I need one item somewhere within the hierarchy. Here is a generic solution that will short-circuit traversal of the hierarchy once a match is found. public static class MyExtensions { public static T

I have a class library with some extension methods written in C# and an old website written in VB. I want to call my extension methods from the VB code but they don't appear in intelisense and I get compile errors when I visit the site. I have got all the required Import s because other classes contained in the same namespaces are appearing fine in Intelisense. Any suggestions EDIT: More info to help with some comments. my implementation looks like this //C# code compiled as DLL namespace x.y { public static class z { public static string q (this string s){ return s + " " + s; } } } and my

I'm trying to call an extension method on my own class, but it fails to compile. Consider the following lines of code: public interface IHelloWorld { } public static class Extensions { public static string HelloWorld(this IHelloWorld ext) { return "Hello world!"; } } public class Test : IHelloWorld { public string SaySomething() { return HelloWorld(); } } Basically I'm extending on the interface. I keep getting this error: The name 'HelloWorld' does not exist in the current context Can anybody explains this to me? When I do a cast all seems well: return ((Test)this).HelloWorld(); Any