Question

In regards to the answer for this question Passing DataContext into Action(), how do I return a value from action(db)?

SimpleUsing.DoUsing(db => { 
// do whatever with db 
}); 

Should be more like:

MyType myType = SimpleUsing.DoUsing<MyType>(db => { 
// do whatever with db.  query buit using db returns MyType.
}); 

Answer 1

Your static method should go from:

public static class SimpleUsing
{
    public static void DoUsing(Action<MyDataContext> action)
    {
        using (MyDataContext db = new MyDataContext())
           action(db);
    }
}

To:

public static class SimpleUsing
{
    public static TResult DoUsing<TResult>(Func<MyDataContext, TResult> action)
    {
        using (MyDataContext db = new MyDataContext())
           return action(db);
    }
}

This answer grew out of comments so I could provide code. For a complete elaboration, please see @sll’s answer below.