I recently started maintaining a .Net 1.1 project and would like to convert it to .Net 3.5.
Any tips to share on reducing code by making use of new features?
As a first attempt, I would like to convert a bunch of static helper functions.
Update: The main reason why I am converting is to learn new features like static classes, LINQ etc. Just for my own use at least for now.
You can use static classes (C# 2.0 feature) to rewrite old helper functions.
I would suggest starting by migrating to .NET 2.0 features, first.
My first step would be to slowly refactor to move all the collections to generic collections. This will help tremendously, and ease the migration into the .NET 3.5 features, especially with LINQ. It should also have a nice impact on your performance, since any collections of value types will perform better.
Be wary in this of converting HashTables to Dictionary<T,U>, since the behavior is different in some cases, but otherwise, ArrayList->List<T>, etc are easy, useful conversions.
After that, moving helpers to static classes, and potentially extension methods, would be a good next step to consider. This can make the code more readable.
If you want to start by "convert[ing] a bunch of static helper functions", then you'll want to check out extension methods.
It's likely that you can use them to make your code simpler and more readable.
If you can swing it, the easiest way I've found to do this is using Visual Studio 2008 and ReSharper. ReSharper will show you, via some kindly visible notation, where you can improve your code. Then it will show you a keyboard shortcut Alt+Enter to "fix" your code.
ReSharper also has a feature called "Cleanup Code" that will will do some of the refactoring for you.
Why convert at all, .Net 1.1 is fully compatible with .Net 3.5, so you should not find any breaking changes when you migrate. If you need to refactor an area because it has problems or you wish to extend it somehow then I would consider migrating to use newer features, but otherwise why touch it and risk breaking it?
Edit As this is a learning excercise rather than changing production code I'd revise my views somewhat; this is probably a good way to learn new approaches. I'd certainly look at LINQ. In places where the old code was iterating through lists or manipulating XML or data from a DB see if you can re-write using LINQ instead.