Month: January 2009

For vs Foreach on arrays and lists

By jonskeet

As promised earlier in the week, here are the results of benchmarking for and foreach. For each of int and double, I created an array and a List<T>, filled it with random data (the same for the list as the array) and ran each of the following ways of summing the collection: A simple for loop, testing the index against the array length / list count each time A for loop with an initial variable remembering the length of the array, then comparing the index against the variable each time A foreach loop against the collection with the type known … Continue reading For vs Foreach on arrays and lists

Programming is hard

By jonskeet

One of the answers to my “controversial opinions” question on Stack Overflow claims that “programming is so easy a five year old can do it.“ I’m sure there are some aspects of programming which a five year old can do. Other parts are apparently very hard though. Today I came to the following conclusion: If your code deals with arbitrary human text, it’s probably broken. (Have you taken the Turkey test recently?) If your code deals with floating point numbers, it’s probably broken. If your code deals with concurrency (whether that means database transactions, threading, whatever), it’s probably broken. If … Continue reading Programming is hard

Benchmarking made easy

By jonskeet

While I was answering a Stack Overflow question on the performance implications of using a for loop instead of a foreach loop (or vice versa) I promised to blog about the results – particularly as I was getting different results to some other posters. On Saturday I started writing the bigger benchmark (which I will post about in the fullness of time) and used a technique that I’d used when answering a different question: have a single timing method and pass it a delegate, expected input and expected output. You can ask a delegate for the associated method and thus … Continue reading Benchmarking made easy

RFID: What I really want it for

By jonskeet

This isn’t really coding related, but it’s technology related at least. There’s been a lot of fuss made about how great or awful RFID is and will be in the future, in terms of usefuless and privacy invasion respectively. There’s one use which I haven’t seen discussed, but which seems pretty obvious to me – but with further enhancements available. Basically, I want RFID on clothes to tell me useful stuff. Suppose each item of clothing were uniquely tagged, and you had a bunch of scanners in your home linked up to one system which stored metadata about the clothes. … Continue reading RFID: What I really want it for

Designing LINQ operators

By jonskeet

I’ve started a small project (I’ll post a link when I’ve actually got something worthwhile to show) with some extra LINQ operators in – things which I think are missing from LINQ to Objects, basically. (I hope to include many of the ideas from an earlier blog post.) That, and a few Stack Overflow questions where I’ve effectively written extra LINQ operators and compared them with other solutions, have made me think about the desirable properties of a LINQ operator – or at least the things you should think about when implementing one. My thoughts so far: Lazy/eager execution If … Continue reading Designing LINQ operators

Quick rant: why isn’t there an Exception(string, params object[]) constructor?

By jonskeet

This Stack Overflow question has reminded me of something I often wish existed in common exception constructors – an overload taking a format string and values. For instance, it would be really nice to be able to write: throw new IOException(“Expected to read {0} bytes but only {1} were available”,                      requiredSize, bytesRead); Of course, with no way of explicitly inheriting constructors (which I almost always want for exceptions, and almost never want for anything else) it would mean yet another overload to copy and paste from another exception, but the times when I’ve actually written it in my own exceptions it’s … Continue reading Quick rant: why isn’t there an Exception(string, params object[]) constructor?

Stack Overflow reputation and being a micro-celebrity

By jonskeet

I’ve considered writing a bit about this before, but not done so for fear of looking like a jerk. I still think I may well end up looking like a jerk, but this is all stuff I’m interested in and I’ll enjoy writing about it, so on we go. Much of this is based on experiences at and around Stack Overflow, and it’s more likely to be interesting to you if you’re a regular there or at least know the basic premises and mechanics. Even then you may well not be particularly interested – as much as anything, this post … Continue reading Stack Overflow reputation and being a micro-celebrity

Stack Overflow Reputation Tool now online

By jonskeet

Update: Now that the “recent activity” page is working, the feed that the tool was using has been removed. However, the new page offers pretty much everything that the tool did, and a lot more besides. I’ve updated the tool to just redirect to the relevant page, so your bookmarks should still work. Original post: This is the micro-web-app that my recent ASP.NET question was about. It’s very simple – it shows you the reputation gained or lost by a specified user (typically you) for either today or yesterday. Note that these are Stack Overflow “today” and “yesterday” – i.e. … Continue reading Stack Overflow Reputation Tool now online

Horrible grotty hack: returning an anonymous type instance

By jonskeet

One of the reasons I don’t view anonymous types as being too bad is that they’re nicely confined to methods. You can’t declare the type that you’re returning from a method if it’s anonymous (or if one of its type arguments is generic, e.g. a List<T> where T is an anonymous type and T isn’t a type parameter to the method itself). However, you can get around this if you’re sneaky. I’ve always known that it’s perfectly easy to return an instance of an anonymous type by declaring that the method will return object. However, it hadn’t occurred to me … Continue reading Horrible grotty hack: returning an anonymous type instance

You don’t have to use query expressions to use LINQ

By jonskeet

LINQ is clearly gaining a fair amount of traction, given the number of posts I see about it on Stack Overflow. However, I’ve noticed an interesting piece of coding style: a lot of developers are using query expressions for every bit of LINQ they write, however trivial. Now, don’t get the wrong idea – I love query expressions as a helpful piece of syntactic sugar. For instance, I’d always pick the query expression form over the “dot notation” form for something like this: var query = from file in Directory.GetFiles(logDirectory, “*.log”)            from line in new LineReader(file)            let entry = new LogEntry(line)            … Continue reading You don’t have to use query expressions to use LINQ