How to refactor these 2 similar methods into one?

Question

I\'ve seen some samples of using \'T\' to make a method reuseable for generic collections of different classes, but I\'ve never really gotten into it or understood the samples.

Answer 1

The old school way would be to create a common interface for both Department and Function:

interface A
{
int ID{get;}
string Description{get;}
}

You implement Description on Department to return d.Code + " - " + d.Description. and write the function to use this interface instead of concrete classes:

[NonAction]
    public List ToSelectList(IEnumerable as, string defaultOption)
    {
        var items = as.Select(a => new SelectListItem() { Text = a.Description, Value = a.Id.ToString() }).ToList();
        items.Insert(0, new SelectListItem() { Text = defaultOption, Value = "-1" });
        return items;
    }

EDIT: Regarding using generics, its not going to help much in this case, because

• the objects you are passing needs to implement Id and Description
• you are not returning these objects, so in this respect you don't have to care about type safety of generics