Partial Class vs Extension Method

Question

I dont have much experience of using these 2 ways to extend a class or create extension methods against a class. By looking others work, I have a question here.

I saw pe

Answer 1

If you choose the Partial Class route but find you are repeating the same code, switch to Extension Methods.

For example, i have many generated classes with methods which return IEnumerable data. I want to extend each class somehow to give me the option of receiving the data in the format IEnumerable.

I have a general requirement here to transform IEnumerable data to IEnumerable. In this case, rather than writing multiple partial class methods an extension method works best:

public static class ExtensionMethods
{
    public static IEnumerable ToMediaItems(this IEnumerable tracks)
    {
        return from t in tracks
               select new MediaItem
               {
                   artist = t.Artist,
                   title = t.Title,
                   // blah blah
               };
    }
}

This gives me the following options:

var data = Playlist.Tracks.ToMediaItems();
var data = Podcast.Tracks.ToMediaItems();
// etc..