What are the limitations of Dynamic Language Runtime in .NET 4.0?

Question

I know that anonymous functions are not supported as arguments to a dynamic method call. What are other such limitations of DLR in .NET 4.0?

Answer 1

You can use anonymous functions, you just have to cast them first:

dynamic list = new List<string>() { "10", "20" };
dynamic converted = list.ConvertAll((Func<string, int>) (x => int.Parse(x)));

The same is true of method group conversions:

foo.Click += (EventHandler) MyClickHandler;

Other restrictions I've encountered so far:

• Static methods and constructors can't be dynamic in terms of the type, but can be dynamic in terms of the arguments
• You can't use dynamic in a type constraint

• You can't use dynamic as a type argument in an interface for a class declaration, but you can use it as a type argument for a base class, i.e.

  class Invalid : IEnumerable<dynamic>
  class Valid : List<dynamic>
  

• Extension methods aren't discoverable at execution time (but you can call the static method directly with dynamic arguments)

• There's a bug in 4.0b1 such that you can't convert from dynamic[] to IEnumerable<dynamic> - that will be fixed for the release.
• You can't use dynamic as a base class

(Note that these are limitations of C# 4.0 as much as of the DLR itself. I got the impression that was what you meant though.)