Rather excitingly, all the chapters of C# in Depth are now available for early access. The following chapters have recently been added:

10: Extension methods

Without extension methods, LINQ just couldn’t work in an elegant form. Extension methods are basically a way of faking instance methods by providing static methods with an implicit “this” parameter. Importantly, they can work on interfaces, which means you can make an interface appear to have many more methods than implementations actually have to provide. Although they’re primarily provided for the sake of LINQ, extension methods can improve code readability in other spheres too – when used cautiously. In this chapter, we look at extension methods in the non-LINQ world, and get our first glance at some of the methods in System.Linq.Enumerable.

11: Query expressions and LINQ to Objects

If you ask someone who has just read a page or two about C# 3 what the new features are, they’ll almost certainly write a query expression. This is the “from x in y where z select foo” type of expression which looks almost like SQL but isn’t. The amazing thing about query expressions is how little they impact the rest of the language: they are pure syntactic sugar, being effectively translated into other source code before being compiled. That allows some really neat tricks, and is the basis for how LINQ handles multiple data sources.

In this chapter we look at query expressions and the standard query operators which support them, via LINQ to Objects. This is “in-process” LINQ, often used with in-memory collections but more generally available for anything implementing IEnumerable or IEnumerable<T>.

12: LINQ beyond collections

We’ve all seen LINQ to SQL demos, and gone “ooh” and “ahh” (or possibly “I could do that in Rails too, y’know”) at the appropriate time. In this chapter I emphatically don’t try to teach you LINQ to SQL, but instead take you on a whistle-stop tour of lots of different LINQ providers:

• LINQ to SQL
• LINQ to DataSet
• LINQ to XML
• LINQ to NHibernate
• LINQ to ActiveDirectory
• LINQ to Entities
• Parallel LINQ

I also give a bit of insight into how “true” LINQ providers like LINQ to SQL (I don’t really count LINQ to XML or LINQ to DataSet – they’re just providing IEnumerable<T>s for LINQ to Objects to work with) work, using IQueryable.

As you can tell from the scope of the chapter, I don’t try to go into many details – just enough to give the flavour, and hopefully show the “big picture”. I believe Microsoft is really trying something very ambitious with a mostly-unified query framework, and with any luck this chapter leaves that as the lasting impression.

13: Elegant code in the new era

I’ve taken a look at a lot of my technical books to see how they end – and really they don’t, properly. The last line of the last chapter could often have been set anywhere else. My final chapter is very short, but tries to give an impression of where I think software development is going, particularly in terms of C#.

Appendix A: LINQ standard query operators

Although some of the standard query operators are covered in chapter 11, there are plenty which aren’t. This appendix is really just a grouped list of the operators with some brief examples of what they do. Handy as a reference guide – one reviewer apparently said to another, “Holy crap! I want this on my wall!”

What next?

So, now that everything is available in MEAP, it’s all done, right? Well, not quite. I’m currently indexing and putting together final revisions – where the word “final” is pretty loose. It will then be passed to my technical reviewer (whose name I shouldn’t reveal just yet, but who I’m proud to have on board – even if I’m dreading the errors they’ll find) and the copy editor, who I believe will work effectively in parallel. After that (and final approval) it will go into production, then to press. The due date is still late March or April at the moment, I believe.

My current indexing/revising task is a real slog (which is why I’m taking a break by writing this blog entry) but I think it’s the last big push – it should get easier when I’m done on this bit. Right, back to chapter 5…