22nd November, 2017

Features

Beta support for the following C# 7.0 features:

• Tuples

  class TestValueTuples
  {
      public (int Key, string Value)[] TestArray;
      public IEnumerator<(int Key, string Value)> TestInnerType;
      public (int Key, string Value) TestField;
      public (int Key, string Value) TestProperty { get; set; }
      public (int Key, string Value) TestMethod() { throw new NotImplementedException(); }
      public Func<(int Key, string Value)> TestFunc;
      public event EventHandler<(int Key, string Value)> TestEvent;
   
      public (int Q, int W) Method1((int Key, string Value) arg)
      {
          Console.WriteLine(TestField.Value);
          Console.WriteLine(TestProperty.Value);
          Console.WriteLine(TestMethod().Value);
          Console.WriteLine(arg.Value);
          Console.WriteLine(TestInnerType.Current.Value);
          Console.WriteLine(TestArray[0].Value);
          Console.WriteLine(TestFunc().Value);
          Console.WriteLine(TestFunc.Invoke().Value);
          TestEvent += (sender, tuple) => { Console.WriteLine(tuple.Value); };
          return (8, 16);
      }
  }

• Out variables

  int TestMethod1(Dictionary<string, int> arg, string key)
  {
      if (!arg.TryGetValue(key, out var result))
          result = 0;
   
      return result;
  }

• Pattern Matching

  int TestMethod1<T>(IEnumerable<T> arg)
  {
      switch (arg)
      {
          case IList<T> tmp:
              return 1;
          case IEnumerable<int> tmp
          when tmp.Any():
              return tmp.First();
          case Queue<T> tmp:
              return 2;
          case Stack<T> tmp:
              return 3;
      }
      
      return 4;
  }
  int TestMethod2<T>(IEnumerable<T> arg)
  {
      if(arg is List<T> list)
          return list.Count;
          
      return 0;
  }
   

• Deconstruction

  class TestDeconstructors
  {
      private int a, b, c;
      public void Deconstruct(out int a, out int b, out int c)
      {
          a = this.a;
          b = this.b;
          c = this.c;
      }
   
      public void Method1(TestDeconstructors other)
      {
          (a, b, c) = other;
      }
  }

• Discards

  int TestMethod1<T>(IEnumerable<T> arg)
  {
      switch (arg)
      {
          case IList<T> _:
              return 1;
          case IEnumerable<int> tmp
          when tmp.Any():
              return tmp.First();
          case Queue<T> _:
              return 2;
          case Stack<int> tmp:
              return tmp.Peek();
      }
   
      return 4;
  }
   
  int TestMethod2<TKey, TResult>(Dictionary<TKey, TResult> arg)
  {
      return arg.TryGetValue(default(TKey), out _) ? 1 : 0;
  }
   

• Literals

  int num = 1_000_000;

• Throw Expressions

  public static void Method1(IEnumerable<int> asd)
  {
   var tmp = (asd as IList<int>) ?? throw new ArgumentNullException(nameof(asd));
  }

Fixes

• RP-4058 - (VsPackage): on F12 Jump, find proper declaration based on metadata line