OoasTools

// Experiment with extension methods and C5, 2007-10-31

// Compile with 

//   csc /r:C5.dll Extension.cs 

using System;

using System.Linq.Expressions;

using C5;

using SCG = System.Collections.Generic;

namespace Extension {

  static class AddOn {

    public static int Added<T>(this ICollection<T> coll, int x) {

      return coll.Count + x;

    }

    public static SCG.IEnumerable<T> Where<T>(this ICollection<T> coll, 

					      Expression<Func<T,bool>> pred) 

    {

      Console.WriteLine("hallo");

      //      Func<T,bool> p = pred.Compile();

      Delegate p = pred.Compile();

      foreach (T item in coll) 

	//  	if (p(item))

  	if ((bool)p.DynamicInvoke(item))

  	  yield return item;

    }

    static void Main(String[] args) {

      HashSet<Person> hs = new HashSet<Person>();

      hs.Add(new Person("Ole"));

      hs.Add(new Person("Hans"));

      foreach (Person q in (from p in hs where p.name.Length == 4 select p))

	Console.WriteLine(q);

    }

  }

  class Person {

    public readonly String name;

    public Person(String name) {

      this.name = name;

    }

    public override String ToString() {

      return name;

    }

  }

}