Indexer in C#

A drawback of indexers in C# is that they can only be given the name of the class in which they're defined - hence the 'this' keyword in the definition. You can't give them some arbitrary name like you can for a non-indexed property.

However, in C# 4.0,  there is an exception to this. When using COM interop, you can access a COM property which takes a parameter or parameters. This (and other enhancements in C# 4.0) makes Office interop much easier. 

Unfortunately, you still can't create arbitrarily named indexed properties in C# 4.0 even if you're creating a COM component.

For more details on this feature, check out:

http://msdn.microsoft.com/en-us/library/ee310208.aspx