Book review/preview: “C# Query Expressions And Supporting Features in C# 3.0” (Eckel/King)


Let me make one thing very clear before anything else: this is a preview. Bruce Eckel has made the preview of what appears to be part of a bigger book available free from his website. The book is by Bruce Eckel and Jamie King, and the preview available (1.0 at the time of writing) covers the following topics:

  • Extension methods
  • Implicitly typed local variables
  • Automatic properties
  • Implicitly-typed arrays
  • Object initializers
  • Collection initializers
  • Anonymous types
  • Lambda expressions
  • Query expression translation

For obvious reasons, this had me slightly worried when I first looked at it – it’s clearly a reasonably direct competitor to C# in Depth. There’s not a lot of C# 3 which isn’t covered here. I can only think of these things off-hand:

  • Expression trees
  • Object initializers setting properties of embedded objects
  • New type inference rules
  • New overload resolution rules

I was surprised to see expression trees not get even a mention. I’m sure they’ll be covered elsewhere in the full book, but I personally think it’s worth introducing them at the around same time as lambda expressions. (It would be odd for me to have any other view, given the location in C# in Depth!) I don’t know whether the new rules for type inference and overload resolution will be covered elsewhere. If they’re going to be covered but the authors haven’t done the writing yet, we should all feel sympathy for them. That section (9.4) was the hardest one in the whole book for me. It may be possible to describe all of the rules in a way which doesn’t make both reader and writer want to tear their hair out, but I have yet to see it.

I don’t know exactly what the bigger book will cover, or how it will be published, or whether it will be available in preview form, etc. From here on in, when I say “the book” I mean “the preview bit”.


After the TOC and introductory material, the book basically consists of 4 things:

  • Headings (occasional)
  • Explanatory text
  • Code
  • Exercises

There are no diagrams or tables as far as I can see. The main body of the book (P7-137) sets exercises quite frequently (there are 54 of them), and the answers form P138-233, including brief explanations.

The code is always complete, including using directives, a Main method (for non-library classes) and output. A lot of the time the code essentially forms unit tests to demonstrate the features (a technique we used in Groovy in Action, by the way). The authors have their own build system which not only runs the tests, but also allows comments to express pieces of code which shouldn’t compile. The output is also checked, i.e. that running the code produces the output in the book.

There are pros and cons to this approach. For those who haven’t read any of my book (what are you waiting for? The first chapter is free!) I personally use a tool I wrote called “Snippy” which allows me to include short but complete examples without using directives and Main declarations appearing everywhere. My comments on this book’s approach:

  • I’d be surprised to see any misleading/broken examples. (There’s one piece of code which doesn’t go quite as far as I believe it should, but that’s a different matter.)
  • It encourages unit testing.
  • It leads to longer code with repetition (Main etc).
  • The build system leads to non-standard comments, like //c! to indicate a non-compiling line and //e! to indicate where an exception should be thrown.
  • There’s a little too much text dealing with the build system – it’s distracting

The “long code” issue has been dealt with by squeezing a lot of code into short spaces – K&R bracing and very little whitespace. Personally I find this really quite tricky to read, to the extent that I ended up skipping a lot of the code examples. I’ve tried to keep all my code examples pretty short, and none of them are over a page. (That was an unstated goal at the start of the project, in fact.)

Now, how much code do you like to see in a book? That’s very much a personal decision. I happen to like quite a lot of explanatory text – so that’s how I write, too. In this book I reckon (and it’s only a complete guess) about 50% of the book is code, 35% is prose and 15% is exercise. This quite possibly pose a challenge for me as a reader if I didn’t already know the topic. However, for other readers it’s probably spot on.

What this book doesn’t have (fortunately) is lots of examples which go on for pages and pages, producing a complete application with little explanation. I’ve seen that too often – and a lot of the code simply doesn’t teach me anything. I’ve never particularly liked the “build a complete application” approach to books, partly because it doesn’t actually mean that all the bases are covered (you don’t see every issue in every app) and it does mean there’s a lot of turn-the-handle code which isn’t relevant to the topic being taught. It can be a useful technique in some situations, but I like it when irrelevant code is omitted (and is just available for download).

The other personal question is whether or not you like exercises. I certainly believe in trying out new things as you read about them, but exercises don’t really fill that need in an ideal way for me. I like to try to apply a new technique to an existing bit of code, or an existing database for instance – and obviously the author has no way of knowing that. Now, that only says something about me, not about the value of exercises. This book has been used for teaching in a university, and I suspect the exercises have been appropriate in that setting. Note for future consideration (and reader feedback): should I include exercises in any future books I might write? Should I create some for the C# in Depth web site?


(Some of this might reasonably count as format as well – it’s a blurry line.)

I have a consciously “light” style. I write in the first person and try to include opinion and the occasional joke or at least lighthearted comment. (Footnote 1 in chapter 3 is my favourite, for reference.)

Eckel and King’s book is more like a textbook. The authors haven’t allowed their personalities to come through in the text at all – and it’s clearly a deliberate decision. Good or bad? Hard to say – it depends on the context. The word “textbook” is the key here, for me – I can’t remember textbooks having any personality when I was a student, so if they’re going for that market it’s spot on. In the “professional developer” market it may have a harder time. Again, personally I’m a fan of a bit of personality peeping through the text – although it has to be firmly controlled, and it’s better to err on the side of caution. I’ve read some books which seem to be all about the author’s personality, without letting the subject matter have a look-in.

I do think more headings (of varying sizes, if you see what I mean) and the occasional diagram would be helpful, though. It’s a pretty unrelenting code-text-code-text-exercise-code-text-code-text mix. The code is all just “there” with no headings, nothing to visually break things up. (It’s not actually run-on with the text – it’s clear where text stops and code starts, and there’s even a helpful vertical line down the side of the code – it’s just that there’s nothing to make you take a mental breath.) This could be due to it being a preview – it’s possible that more formatting will occur later on. If that wasn’t the plan, I’d encourage the authors to at least consider it. (Wow, see how easy it is to slip into arrogance? Must make a memo to give Joel Spolsky some notes on writing later ;)


The content is pretty full-on, and very language-focused. As an example, I suspect few books on C# 3 will go into any detail about transparent identifiers in query expressions. In my book I explain them for one particular clause (“let”) and then just mention when the compiler will introduce one for other clauses. Eckel and King’s book gives full exampes of translation for all the clauses available, as far as I can tell.

That’s just an example – and possibly an extreme one – but this book does go into a reasonable amount of depth when it comes to the facts. (There were also two items I wasn’t aware of: the option of explicitly stating that an ordering is ascending, and the ability to create “extension delegates“. They’re not huge omissions in my text (and at least I’ve now got notes for them), but the fact that I missed them and these guys didn’t is (to me) an indication of their thoroughness.

Now, having dealt with the plain facts, there’s not a lot of opinion in the book – pieces of text which encourage the reader to think about why C# has changed the way it has, or the best way to take advantage of those changes. Again, this is a valid approach for a textbook – especially one used in conjunction with a course where the lecturer can talk about these things – but I suspect the non-academic market likes guidance.

The accuracy level seemed pretty high to me. Not perfect, but then I don’t expect mine is either, even with Eric’s thorough eye. In everyone’s interests, I’ve mailed the authors my specific comments and nitpicks – as the book is still at a preview stage, corrections can be made relatively easily, I expect.


Obviously I can only comment on the book as I’ve seen it so far – I’ve no idea whether the other chapters will be more framework-focused. However, it’s good to see another book that tries to “go deep” like mine does. While this clearly makes it competition in many ways, I think we’re aiming at different audiences. If I’m right in my assumption that this is trying to be a textbook, there may be little overlap in potential market. (I suspect the same will be true of Head First C#, which is likely to be my next review – but for the opposite reason. I suspect I’ll find that HFC# is more aimed at beginners – something that certainly couldn’t be said of this book or mine.)

Overall this is a very solid text, in many senses. It’s not the easiest book to follow due to its style, but it’s detailed and accurate. Given a choice between the latter and the former, I’d always choose the latter for anything I’d want to refer back to – and this book certainly counts as a good reference for query expressions. Obviously I’m hoping people find my style appealing and that I’m detailed and accurate, but I can’t give that judgement.

As a final word – if you haven’t downloaded it yet, why not? It’s a totally free download of only just over a meg. I don’t think I even had to register anywhere to get it. Reading other work is useful for me as a writer, but there’s no need for you to trust my judgement, nor indeed would it be wise to do so. If you missed it before, I’ll even save you scrolling up for the download link.

I’d be interested to hear whether your opinions coincide with mine. If you’ve read my book and can compare and contrast, so much the better. I’ve let the authors know that this review is coming, so I suspect they’ll be checking here for feedback. (They’d be foolish not to, and I have no reason to believe they’re fools.)

4 thoughts on “Book review/preview: “C# Query Expressions And Supporting Features in C# 3.0” (Eckel/King)”

  1. Checking…

    Jon has given us a focused and excellent feedback. I only met him a few days ago, and yet feel in his debt simply because of the depth of review he’s given us here and also via e-mail.

    Now my turn to look at what he’s made available… ;)

    Thanks again Jon


  2. Well, the blatant i18n issue in the first example probably set me off on the wrong foot.

    I’ve read a few pages so far (time) and I must admit that I’m not “warming” to it all that much – I think mainly the writing style…

    But even from just a few pages I have a list of gripes; I won’t post them here (my intent isn’t to publicly flame – it is the same type of observational feedback I offered for “C# in Depth”) – but [if they see your blog] the authors are freely welcome to my thoughts.


  3. Thanks for the link! I wasn’t aware of this book, I’ll have to take a look at the PDF sample.

    Agreed about code samples and exercises. Huge code listings strike me as (intentionally?) wasted space, and exercises as marketing aimed at universities and similar institutes. I certainly never do any exercises when I’m reading a book on my own…


  4. Jenny and I are psyched that you’re going to review our book, Head First C#! It’ll be great to get objective feedback on it. We did our best to make it entertaining, even to someone who’s been programming a long time.

    You’re right, we did aim it at beginners. But one piece of feedback we’ve gotten is that it seems to be really useful to programmers who know other languages but don’t have a lot of experience with object oriented design.

    We’re looking forward to seeing what you think!



Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s