New C# Language Features

I've been considering whether to update my C# vs. Java article with the upcoming features of both languages which seem to be converging ever faster given the announcements Sun has made about Tiger 1.5. It seems the conclusion I drew in the article that

It is my opinion that both languages are similar enough that they could be made to mirror each other without significant effort if so required by either user base. In this case, C# would have it easier than Java in that C# has less to borrow from Java than Java would have to borrow from C#.

is turning out to be very true. The article gets about 1500 to 2000 hits a month so I assume there are literally 1000s of developers who would benefit if I did so. I wonder what any of the readers of the original article think?

I talked to Eric Gunnerson a few days before OOPSLA about his teams plans for C# but was still blown away by Anders Hejlsberg's presentation. The most compelling feature to me is generics but the devs on my team seem to like iterators a lot. Specifically I think

1. Generics: This feature really feels like C++ Templates++. Besides compile time checking and being able to apply on everything from classes to methods they do one thing that C++ templates do not but Bjarne Stroustrup has been talking about for a while. C# generics support constraints on generic arguments (read the topic Constraints for template arguments in my "C++ in 2005" article for more info on this from the C++ perspective) using a where clause. The following code snippet from the presentation is shows this supremely cool feature
   
   interface IComparable<T> { int CompareTo(T obj); }
   
   class Dictionary<K, V>: IDictionary<K, V> where
      K: IComparable<K>,
      V: IKeyProvider<K>,
      V: IPersistable,
      V: new()
   {
      ...
   }
   
   
   
2. Iterators: C# enables any class to be iterated over using the foreach keyword as long as it contains a method named GetEnumerator() that returns a type with a Current property and a MoveNext() method. The compiler knows to convert each foreach to the calls to the appropriate methods. Iterators seem to add more indirection via foreach() member functions which now allow the compiler not only to rewrite the foreach loop correctly but also codegen the GetEnumerator() method and the type it returns. A practical example from the presentation is that the code
   
   public class List
   {
      internal object[] elements;
      internal int count;
   
      public ListEnumerator GetEnumerator() {      return new ListEnumerator(this);
      }
   }
   
   public class ListEnumerator
   {
      List list;
      int index;
      object current;
   
      internal ListEnumerator(List list) {
         this.list = list;
      }
   
      public bool MoveNext() {
         if (index >= list.count) {
            current = null;
            return false;
         }
         current = list.elements[index++];
         return true;
      }
   
      public object Current {
         get { return current; }
      }
   }
   
   
   

   shrinks to

   
   
   public class List
   {
      internal object[] elements;
      internal int count;
   
      public object foreach() {
         for (int i = 0; i < count; i++) yield elements[i];
      }
   }
   
   
   OK, that yield keyword is pretty cool.
   
   
3. Anonymous Methods: This fixes the lack of anonymous inner classes in C# by adding anonymous methods for use in the exact same situations most people use anonymous inner classes for. I actually think it is cleaner for it to be anonymous methods and that this brings C# one step closer to having closures.
   
   
4. Partial Types: This is a pretty ho hum feature to me. Allowing classes to be defined in multiple files seems to be bowing to user pressure from users who have bad design. If your class is so big that it needs to be defined in multiple files then doesn't that create a bad smell?

I have raised an issue with the C# folks about what adding new keywords to the language would mean for people who try to compile apps written against v1.0 of C# and used variable names like yield or partial. They seem to be aware of it but feedback from the C# user community at large will probably have more impact in deciding how they'll tackle this problem.

#

I-Spy Movie Review

This is yet another mismatched-pair buddy cop spy movie. Good movies in this genre include the Rush Hour and Lethal Weapon series while bad movies in this genre include garbage like Showtime. I-Spy is no Rush Hour but it did have a few scenes which I considered laugh out loud funny. The funniest scene is a redo of the formulaic Cyrano De Bergerac joke where the smooth playa (Eddie Murphy) puts words in the mouth of the novice at love (Wilson) in attempt to help him get the girl. The plot isn't much (invisible jet? riiiiight) but is just enough to hang a number of formulaic jokes off of. The only reason I wouldn't give this movie two thumbs up is that they resorted to the most overused spy movie clichè in a move that actually detracted from the plot instead of adding to it.

Carnage4Life Score: *** out of *****

#

Seattle's Wonderful Weather

10-Day Forecast for Seattle, WA. My girlfriend owes me a viewing of the Lord of the Rings: Fellowship of the Ring DVD the next rainy weekend we have together. It looks like next weekend is it. Yaaay, Seattle weather.

#