How is the upcoming 'dynamic' keyword in .net 4.0 going to make my life better?

Question

I don't quite get what it's going to let me do (or get away with :)

Answer 1

From Charlie Calvert's blog:

Useful Scenarios

There are three primary scenarios that will be enabled by the new support for dynamic lookup:

1. Office automation and other COM Interop scenarios
2. Consuming types written in dynamic languages
3. Enhanced support for reflection

Read more here: http://blogs.msdn.com/charlie/archive/2008/01/25/future-focus.aspx

Answer 2

The two big areas are:

• working with COM assemblies where methods return vague types - so you can essentially use late binding
• working with DLR types

Other uses include things like:

• duck-typing where there is no interface
• Silverlight talking to the host page's DOM
• talking to an xml file.

In C# itself, this allows a few things, such as a basic approach to generic operators:

static T Add<T>(T arg1, T arg2) { // doesn't work in CTP
     return ((dynamic)arg1) + ((dynamic)arg2);
}

(of course, I'd argue that this is a better (more efficient) answer to this)

Answer 3

There are some podcasts about the feature itself and how it can be used:

• Inside C# 4.0: dynamic typing, optional parameters, covariance and contravariance
• C# 4.0 New Features - COM Interop Enhancements
• deCast - Dynamic Xml with C# 4.0 "will illustrate how you can take advantage of the dynamic functionality enabled in C# 4.0 to access Xml data in a more natural way"