Question

Often I find myself filling ASP.NET repeaters with items that need the CSS class set depending on index: ‘first’ for index 0, ‘last’ for index (length-1), and ‘mid’ in the middle:

_repeater.DataSource = from f in foos                        select new                        {                          ...,                          CssClass = MakeCssClass( foos, f )                        };   private static string MakeCssClass( Foo[] foos, Foo f ) {   var index = Array.IndexOf( foos, f );    if( index == 0 )   {     return 'first';   }   else if( index == foos.Length - 1 )   {     return 'last';   }   else   {     return 'mid';   } } 

Is there a nicer way I can achieve this (eg using lambda functions)? If I try I get CS0828, ‘Cannot assign lambda expression to anonymous type property’.

Answer 1

You might be interested in my SmartEnumerable type in MiscUtil.

From the usage page, there’s an example:

using System; using System.Collections.Generic;  using MiscUtil.Collections;  class Example {     static void Main(string[] args)     {         List<string> list = new List<string>();         list.Add('a');         list.Add('b');         list.Add('c');         list.Add('d');         list.Add('e');          foreach (SmartEnumerable<string>.Entry entry in                  new SmartEnumerable<string>(list))         {             Console.WriteLine ('{0,-7} {1} ({2}) {3}',                                entry.IsLast  ? 'Last ->' : '',                                entry.Value,                                entry.Index,                                entry.IsFirst ? '<- First' : '');         }     } } 

With implicitly typed variables and a bit more type inference the syntax could be tidied up quite easily. I must get round to that some time, but the basics are already there.