C# v4.0 - Visual Studio 2010

Optional Parameters

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Named Parameters

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Parameterized Properties

This also includes Indexed Properties
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Late Binding - dynamic

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Variance

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Embedded PIAs

These can be embedded into your assembly so that you don't have to deploy them alongside your application
This means that my application is now independent of the version of excel that is installed on a machine.
This automatically includes all the PIA type references used in the project and therefore removes the need to install the PIA prior to deployment Include a screen shot of this for the Excel PIA
There is an "Embed Interop Type" property associated with each interop reference assembly

BigInteger

System.Numerics.BigInteger
Double can hold 16 bit values but BigInteger has no minimum size or maximum size
You cannot use the Math class with BigInteger

Complex Numbers

System.Numerics.Complex

Tuples

System.Tuple
A tuple is a data structure that has a specific number and sequence of elements
The framework directly supports tuples with one to seven elements
You can create tuples of either or more elements by nesting tuple objects in the Rest property

Dynamic Support

Dynamic language runtime ?

Lazy <T>

Lazy instantiation defers the creation of an object until it is actually accessed.
Object creation is always expensive because it involves allocation of memory on the heap

SortedSet Collection

Represents a collection of objects that are maintained in a sorted order
System.Collections.Generic.SortedSet

Tasks

These are much more powerful than the Backgroundworker