Month: September 2010

Book Review: Effective C# (2nd edition) by Bill Wagner

By jonskeet

Resources: Amazon, Barnes and Noble Bill Wagner’s blog Disclaimer Just in case you’re unaware, I’m the author of another C# book, C# in Depth. Although Effective C# is somewhat different to my book, they certainly share a target audience. To that extent, Bill and I are competitors. I try hard to stay unbiased in reviews, but it’s probably impossible. Bear this in mind while reading. I should also note that I didn’t buy my copy of Effective C#; it was kindly sent to me by Pearson, for the purpose of reviewing. Content and target audience Effective C# is a style … Continue reading Book Review: Effective C# (2nd edition) by Bill Wagner

Non-iterable collection initializers

By jonskeet

Yesterday on Stack Overflow, I mentioned that sometimes I make a type implement IEnumerable just so that I can use collection initializers with it. In such a situation, I use explicit interface implementation (despite not really needing to – I’m not implementing IEnumerable<T>) and leave it throwing a NotImplementedException. (EDIT: As noted in the comments, throwing NotSupportedException would probably be more appropriate. In many cases it would actually be pretty easy to implement this in some sort of meaningful fashion… although I quite like throwing an exception to indicate that it’s not really intended to be treated as a sequence.) … Continue reading Non-iterable collection initializers

You are all individuals! (I’m not…)

By jonskeet

I’ve been meaning to post this for a while, but recently a couple of events have coincided, reminding me about the issue. First, Joe Duffy blogged in defence of premature optimization. Second, I started reading Bill Wagner’s Effective C#, 2nd edition, which contains advice such as "make almost all your types serializable". Now, let’s be clear: I have a great deal of respect for both of these gentlemen… but in both cases I think there’s a problem: to some extent they’re assuming a certain type of development. In some cases, you really, really want to understand the nuts and bolts … Continue reading You are all individuals! (I’m not…)

Reply to a reply… tweaking refactoring

By jonskeet

This is a reply to Ben Alabaster’s blog post, which is itself a reply. You can follow the trail yourself. I’ll assume you’ve read the post – I’m not going to go over anything already written there, other than my comments. I took issue with three aspects of Ben’s refactoring: The use of float for currency The fact that "BaseRate" effectively doesn’t have a well-defined unit; in some cases it’s "dollars per hour" and in others it’s "dollars per pay cheque, regardless of hours" smells The use of properties for the pay functions I’ll tackle the last one first, because … Continue reading Reply to a reply… tweaking refactoring

Query expression syntax: continuations

By jonskeet

In this Stack Overflow question, I used a query continuation from a select clause, and one commenter expressed surprise, being unaware of what "select … into" meant. He asked for any references beyond the MSDN "into" page, and I didn’t know of any specific ones. So, here’s a very quick guide. When "into" is used after either a "group x by y" or "select x" clause, it’s called a query continuation. (Note that "join … into" clauses are not query continuations; they’re very different.) A query continuation effectively says, "I’ve finished one query, and I want to do another one … Continue reading Query expression syntax: continuations

Mini-post: abstractions vs repetition; a driving analogy

By jonskeet

Driving Tom back from a children’s party this afternoon, I was thinking about Noda Time. I’ve been planning to rework the parsing/formatting API, so that each chronological type (ZonedDateTime, LocalDateTime, LocalDate, LocalTime) has its own formatter and parser pair. I suspect this will involve quite a bit of similar code between the various classes… but code which is easy to understand and easy to test in its simple form. The question which is hard to answer before the first implementation is whether it will be worth trying to abstract out that similar code to avoid repetition. In my experience, quite … Continue reading Mini-post: abstractions vs repetition; a driving analogy

Very quick interlude: I know that CAPTCHAs aren’t working on this blog if you’re using Chrome

By jonskeet

This is just a quick post to hopefully stem the tide of people commenting (in blog comments and Twitter messages) saying that this blog is broken when it comes to CAPTCHAs and Chrome. I know, but there’s nothing I can do about it – I don’t run the software on the blog. I haven’t looked into why it’s not working… if you open the image in a new tab, it displays that fine. Weird, but such is life… I’m hoping that an update to either Community Server or Chrome will fix it eventually.

Reimplementing LINQ to Objects: Part 2 – "Where"

By jonskeet

Warning: this post is quite long. Although I’ve chosen a simple operator to implement, we’ll encounter a few of the corner cases and principles involved in LINQ along the way. This will also be a somewhat experimental post in terms of format, as I try to work out the best way of presenting the material. We’re going to implement the "Where" clause/method/operator. It’s reasonably simple to understand in general, but goes into all of the deferred execution and streaming bits which can cause problems. It’s generic, but only uses one type parameter (which is a big deal, IMO – the … Continue reading Reimplementing LINQ to Objects: Part 2 – "Where"

Reimplementing LINQ to Objects: Part 1 – Introduction

By jonskeet

About a year and a half ago, I gave a talk at a DDD day in Reading, attempting to reimplement as much of LINQ to Objects as possible in an hour. Based on the feedback from the session, I went far too fast… and I was still a long way from finishing. However, I still think it’s an interesting exercise, so I thought I’d do it again in a more leisurely way, blogging as I go. Everything will be under the "Edulinq" tag, so that’s the best way to get all the parts in order, without any of my other … Continue reading Reimplementing LINQ to Objects: Part 1 – Introduction

Presentation preparation

By jonskeet

As most of you know, I occasionally talk about C# at conferences, user groups or basically anywhere that people won’t attack me. A while ago I rejected PowerPoint in favour of a rather less formal approach: hand-drawn slides. Quite a few people have now asked me about how they’re prepared – even occasionally making the assumption that my awful handwriting is actually a real font – so I figured it’s worth a blog post. My process is both primitive and complex… 1. Draw the slides I use plain A4 printer paper and a black flipchart marker to draw the slides. … Continue reading Presentation preparation