Future of C#

New and exciting functionality is coming our way with C#4. The dynamic programming support being the most interesting of all, along with “Compiler as a Service” approach, which I am hoping to see in not too distant future. Continuing the trend from my previous two posts, here are the notes I made while watching the PDC presentation by Anders Hejlsberg.

• Declarative programming = Less of how it should be done and more of what should be done as compared to Imperative programming which is the opposite
• C#4
  • Major feature is dynamic programming
  • Talking to anything that is not a .NET class
  • Innovations
    - Dynamically typed objects
    - Optional and Named parameters
    - Improved COM interoperability
    - Co- and Contra-variance
• .NET Dynamic Programming
  • DLR
    • Expression Trees
    • Dynamic Dispatch
    • Call Site Caching
  • Object binders allow communication with .NET, Silverlight, Python, Ruby and Office
• Declaring dynamic types in C#4
  • New keyword ‘dynamic’
  • dynamic car = GetCar();
  • So things can be statically typed to be dynamic
  • Dynamic conversion when you are using dynamically typed objects
  • Anything can be assigned to a dynamic type
  • Member type gets differed to runtime type
  • How does this work under the hood
  • Objects implement IDynamicObject
• Optional and Named Parameters
  • You can default values in method parameters making them optional
  • You can specify the named parameter in the method call e.g. Car.GetTyre(1, tyreType: “Back”)
  • Improved COM Interoperability
  • Automatic object > Dynamic mapping. This will automatically convert objects to dynamic.
    • Optional and named parameters
    • Indexed properties
    • Optional “ref” modifier
    • Interop type embedding (“No PIA”): Primary interop assembly
    • No more ref.missing
• Co- and Contra-variance
  • Generics have been invariant
  • C# supports co-variance but not safe co-variance
  • C#4 you can specify ‘in’ or ‘out’ parameters for co and contra variance
  • out = co-variant, can be treated as less derived
  • in = contra-variant: Input precision only, can be treated as more derived
• Compiler as a service
  • Opening up the compiler
  • Meta – programming
  • Language Object Model
  • DSL Embedding
  • Compiler as an API
  • Bad news:Dont know when this will ship