Speaker: Ivan T
C# 4.0 Generic co- and contra-variance Covariance Contravariance IEnumerable<t> is safe as only enumerating members. Won't be adding other subtype to collection. IComparer<t> - If T appears onlay as an output, it's safe to pass X<tderived> for X<t> - covariance - C# syntax X<out> If T appears only as an input, it's safe to pass Xfor X - countravariance - C# syntax X<int> List and IList are not supported but IComparer and IEnumerable do support. Optional and named parameters - Optional public static virtual DoStuff(int first, int second = 123, int third = 456) { } DoStuff(888); Not creating an Overload. Default value is stored in the calling assembly. Something to consider when versioning the libraries. Not for external publicly visible methods. DoStuff(888, third: 999); Dynamic Programming Dynamic Language Runtime COM interop "No PIA" Primary Interop Assembly - Merge COM interop type definitions into the calling assembly. - Reduces total project size. COM interop enhancements - Can now leave out unnecessary arguments, auto fill in "ref missing" arguments and identify parameters by name. - Dynamic helps with weak typing problem. Tuple - Simple way of packaging up data into a single object without creating the actual implementation. Not meaningful property names. Tuple.Create(true, "bob"); Imutable
