C#

Micro-optimization: the surprising inefficiency of readonly fields

By jonskeet

Introduction Recently I’ve been optimizing the heck out of Noda Time. Most of the time this has been a case of the normal measurement, find bottlenecks, carefully analyse them, lather, rinse, repeat. Yesterday I had a hunch about a particular cost, and decided to experiment… leading to a surprising optimization. Noda Time’s core types are mostly value types – date/time values are naturally value types, just as DateTime and DateTimeOffset are in the BCL. Noda Time’s types are a bit bigger than most value types, however – the largest being ZonedDateTime, weighing in at 40 bytes in an x64 CLR … Continue reading Micro-optimization: the surprising inefficiency of readonly fields

Diagnosing Portable Class Libraries

By jonskeet

I’ve always found Portable Class Library (PCL) configuration to be a bit of a mystery. In simple cases, it’s simple: start a new PCL project in Visual Studio, select the environments you want to support, and away you go. But what’s going on under the hood, and what do all the options mean? How do I do this without Visual Studio? Background: supporting Universal Windows Applications in Noda Time Recently, I had a feature request for Noda Time to support Windows Phone 8.1 and Universal Windows Applications. This is something I haven’t done before, but it doesn’t sound too hard … Continue reading Diagnosing Portable Class Libraries

Extension methods, explicitly implemented interfaces and collection initializers

By jonskeet

This post is the answer to yesterday’s brainteaser. As a reminder, I was asking what purpose this code might have: public static class Extensions  {      public static void Add<T>(this ICollection<T> source, T item)      {          source.Add(item);      }  } There are plenty of answers, varying from completely incorrect (sorry!) to pretty much spot on. As many people noticed, ICollection<T> already has an Add method taking an item of type T. So what difference could this make? Well, consider LinkedList<T>, which implements ICollection<T>, used as below: // Invalid LinkedList<int> list = new LinkedList<int>(); list.Add(10); That’s not valid code (normally)…. whereas this is: // … Continue reading Extension methods, explicitly implemented interfaces and collection initializers

Quick brainteaser

By jonskeet

Just a really quick one today… What’s the point of this code? Does it have any point at all? public static class Extensions {     public static void Add<T>(this ICollection<T> source, T item)     {         source.Add(item);     } } Bonus marks if you can work out what made me think about it. I suggest you ROT-13 answers to avoid spoilers for other readers.

A tale of two puzzles

By jonskeet

As I begin to write this, I’m in a small cubicle in Philadelphia airport, on my way back from CodeMash – a wonderful conference (yet again) which I feel privileged to have attended. Personal top highlights definitely include Dustin Campbell’s talk on C# 6 (I’m practically dribbling with anticipation – bits please!) and playing Settlers of Catan on an enormous board. Kevin Pilch-Bisson’s talk on scriptcs was fabulous too, not least because he demonstrated its NuGet support using Noda Time. I’m very likely to use scriptcs as a tool to ease folks into the language gently if I ever get … Continue reading A tale of two puzzles

Casting vs "as" – embracing exceptions

By jonskeet

(I’ve ended up commenting on this issue on Stack Overflow quite a few times, so I figured it would be worth writing a blog post to refer to in the future.) There are lots of ways of converting values from one type to another – either changing the compile-time type but actually keeping the value the same, or actually changing the value (for example converting int to double). This post will not go into all of those – it would be enormous – just two of them, in one specific situation. The situation we’re interested in here is where you … Continue reading Casting vs "as" – embracing exceptions

Array covariance: not just ugly, but slow too

By jonskeet

It seems to be quite a long time since I’ve written a genuine "code" blog post. Time to fix that. This material may well be covered elsewhere – it’s certainly not terrifically original, and I’ve been meaning to post about it for a long time. In particular, I remember mentioning it at CodeMash in 2012. Anyway, the time has now come. Refresher on array covariance Just as a bit of background before we delve into the performance aspect, let me remind you what array covariance is, and when it applies. The basic idea is that C# allows a reference conversion … Continue reading Array covariance: not just ugly, but slow too

New tool to play with: SemanticMerge

By jonskeet

A little while ago I was contacted about a new merge tool from the company behind PlasticSCM. (I haven’t used Plastic myself, but I’d heard of it.) My initial reaction was that I wasn’t interested in anything which required me to learn yet another source control system, but SemanticMerge is independent of PlasticSCM. My interested was piqued when I learned that SemanticMerge is actually built on Roslyn. I don’t generally care much about implementation details, but I’m looking out for uses of Roslyn outside Microsoft, partly to see if I can gain any inspiration for using it myself. Between the … Continue reading New tool to play with: SemanticMerge

C# in Depth 3rd edition available for early access, plus a discount code…

By jonskeet

Readers who follow me on Twitter or Google+ know this already, but… The third edition of C# in Depth is now available for early access from its page on the Manning website. I’ve been given a special discount code which expires at midnight EST on February 17th, so be quick if you want to use it – it gives 50% off either version. The code is “csharpsk”. It’s likely that we’ll have a separate (permanent) discount for readers who already own the second edition, but the details of that haven’t been decided yet. Just to be clear, the third edition … Continue reading C# in Depth 3rd edition available for early access, plus a discount code…

Fun with Object and Collection Initializers

By jonskeet

Gosh it feels like a long time since I’ve blogged – particularly since I’ve blogged anything really C#-language-related. At some point I want to blog about my two CodeMash 2013 sessions (making the C# compiler/team cry, and learning lessons about API design from the Spice Girls) but those will take significant time – so here’s a quick post about object and collection initializers instead. Two interesting little oddities… Is it an object initializer? Is it a collection initializer? No, it’s a syntax error! The first part came out of a real life situation – FakeDateTimeZoneSource, if you want to look … Continue reading Fun with Object and Collection Initializers