C# Beginner: Where has my IList.Where() method gone?
c#, class, ilist, where-clause
Solution
You need a using directive for `System.Linq`. `.Where()` is an extension method on `IEnumerable<T>` (which `IList<T>` implements) that is defined in the System.Linq namespace.
Problem
I've got another simple one (I think) that's stumping me. I have written a method in one of my controls that gets the latest version of a file in a CMS given it's filename (i.e. regardless of what folder the file resides in). I found it useful enough that I thought I'd chuck it in my CMSToolbox class, but when I do this I can no longer use the `Where()` method of a FileManager class provided by the CMS (which returns a list). Here's a simplified example of my class: ``` using System; using System.Collections.Generic; using CMS.CMS; using CMS.Core; using CMS.Web; namespace CoA.CMS { public class ToolBox { public CMS.CMS.File getLatestFileVersionByFilename(string filename, int GroupID) { IList<CMS.CMS.File> fileWithName = FileManager.GetGroupAll(false, GroupID).Where(file => currentFileVersionIsNamed(file, filename)).ToList<CMS.CMS.File>(); return getLatestFileFromListOfFiles(fileWithName); } protected bool currentFileVersionIsNamed(CMS.CMS.File file, string name) { } protected CMS.CMS.File getLatestFileFromListOfFiles(CMS.CMS.File file) { } } } ``` When I do exactly the same thing in the context of a Control (really a class provided by the CMS which extends `Control`) I have access to the `Where()` method, but in my ToolBox class I don't. What gives? I figured that an `IList` would always allow access to the same methods from wherever you use it. I'm a wrong again, haha :) Edit: `Filemanager.GetGroupAll()` returns a `CMSList` which extends `IList`