C# lambda expressions as function arguments

Question

I\'ve been busy diving into lambda expressions recently, and there\'s some specific functionality that I\'ve been meaning to learn but just couldn\'t seem to make heads or t

Answer 1

You're looking for Action<> and Func<>.

Answer 2

You can create extension

public static class MakeArrayExtension
{
    public static U[] MakeArray<T, U>(this IEnumerable<T> collection, Func<T,U> func)
    {
        return collection.Select(func).ToArray();
    }
}

And then use it like this

List<A> foo; // assuming this is populated
string[] bar = foo.MakeArray<A,string>(x => x.StringProperty);

Answer 3

public static U[] MakeArray<T, U>(this IEnumerable<T> @enum, Func<T, U> rule)
{
    return @enum.Select(rule).ToArray();
}

Answer 4

You can use the Func and Action classes. Check out the LINQ Where function's signature for an example: http://msdn.microsoft.com/en-us/library/bb534803.aspx

Answer 5

Try the following

U[] MakeArray<T,U>(Func<T, U> projection) where T : IEntity {
  ...
}

When passing lambdas as arguments you generally want the matching parameter to be a delegate. In most cases you should just use the appropriate Action<> or Func<> value. The former for void returning lambdas and the latter for ones that return values.