One other useful (and extremely powerful) feature we are enabling with Razor is the ability to pass “inline template” parameters to helper methods.  These “inline templates” can contain both HTML and code, and can be invoked on-demand by helper methods.

Below is an example of this feature in action using a “Grid” HTML Helper that renders a DataGrid to the client:

The Grid.Render() method call above is C#.  We are using the new C# named parameter syntax to pass strongly-typed arguments to the Grid.Render method - which means we get full statement completion/intellisense and compile-time checking for the above syntax.

The “format” parameter we are passing when defining columns is an “inline template” – which contains both custom html and code, and which we can use to customize the format of the data.  What is powerful about this is that the Grid helper can invoke our inline template as a delegate method, and invoke it as needed and as many times as it wants. In the scenario above it will call it each time it renders a row in the grid – and pass in the “item” that our template can use to display the appropriate response.

This capability will enable much richer HTML helper methods to be developed.  You’ll be able to implement them using both a code approach (like the way you build extension methods today) as well as using the declarative @helper {} approach.