Coolest C# LINQ/Lambdas trick you've ever pulled?

Question

Saw a post about hidden features in C# but not a lot of people have written linq/lambdas example so... I wonder...

What\'s the coolest (as in the most

Answer 1

Working with attributes:

private void WriteMemberDescriptions(Type type)
{
    var descriptions =
        from member in type.GetMembers()
        let attributes = member.GetAttributes(true)
        let attribute = attributes.FirstOrDefault()
        where attribute != null
        select new
        {
            Member = member.Name,
            Text = attribute.Description
        };

        foreach(var description in descriptions)
        {
            Console.WriteLine("{0}: {1}", description.Member, description.Text);
        }
}

The GetAttributes extension method:

public static class AttributeSelection
{
    public static IEnumerable GetAttributes(this ICustomAttributeProvider provider, bool inherit) where T : Attribute
    {
        if(provider == null)
        {
            throw new ArgumentNullException("provider");
        }

        return provider.GetCustomAttributes(typeof(T), inherit).Cast();
    }
}

AttributeSelection is production code and also defines GetAttribute and HasAttribute. I chose to use the let and where clauses in this example.