Month: January 2008

Immutability and inheritance

By jonskeet

In my book, I present an example of a Range<T> class do demonstrate iterator blocks. The range allows you to iterate over each element within it in the obvious fashion. There’s an abstract base class, and then a couple of concrete classes derived from that – enough to show the pattern. The base class is abstract because there’s a single abstract method, GetNextValue, which is required to take a current value and return the next one in the sequence. How this occurs depends on the types involved – in the case of a range of DateTime elements, it will add … Continue reading Immutability and inheritance

Bridging gaps, and finding my role

By jonskeet

Warning: this post won’t teach you anything technical. It’s about how I see myself. That may be of interest to you, or it may not. If not, feel free to skip it knowing you’re not missing anything else. One of the great problems of the world today is undoubtedly this problem of not being able to talk to scientists, because we don’t understand science. They can’t talk to us because they don’t understand anything else, poor dears. (Michael Flanders) For a while, I’ve made myself slightly miserable (only slightly – I’m generally a very happy guy) by seeing just how … Continue reading Bridging gaps, and finding my role

Types of Parallelism

By jonskeet

When I was at TechEd, Joe Duffy mentioned task parallelism and data parallelism a number of times. It was easy enough to follow what he meant, but I had to keep consciously thinking about the terms instead of instinctively knowing what they meant. This post is intended to ram the point home to me as much as anyone else – there’s nothing like writing things up to make them stick in your head. I thought I had a modicum of success with my “real life example” in the post about “push” LINQ, so I’ll use another one here. The difference … Continue reading Types of Parallelism

Extension methods on lamdba expressions don’t work, unfortunately

By jonskeet

Over the Christmas holidays, I thought I’d experiment with something I’d been thinking about a little – sorting a generic IList<T>. Now, before anyone gets huffy, I’m well aware of OrderBy in LINQ to Objects. However, sometimes you want to sort collections in-place, and as IList<T> provides random access, there’s no reason we shouldn’t be able to. Now, I do like the way that OrderBy allows multiple criteria to be specified, whether they should be applied in an ascending or descending fashion, and by way of just “compare by this projection” rather than having to actually implement the comparison yourself. … Continue reading Extension methods on lamdba expressions don’t work, unfortunately

LINQ to Objects – not just for in-memory collections

By jonskeet

I’ve just seen LINQ to Objects described as the LINQ provider for “in-memory collections” again. It’s a fairly frequent occurrence, and I may have done it myself on occasion. It doesn’t do LINQ to Objects justice. An example I’ve used in a few places is a query which runs over log files. Something along the lines of: var query = from file in Directory.GetFiles(@“c:\logs”, “*.log”)            from line in new LineReader(file)            let entry = new LogEntry(line)            where entry.Severity = Severity.Critical            select entry; Where’s the in-memory collection here? I suppose there’s the array of log file names, but that’s about it. LINQ to … Continue reading LINQ to Objects – not just for in-memory collections

"Push" LINQ revisited – next attempt at an explanation

By jonskeet

Marc Gravell and I have now implemented a lot of LINQ standard query operators on the “push” model of IDataProducer as opposed to the “pull” model of IEnumerable. My good friend Douglas Leeder (who doesn’t use C#) has been with me this weekend, and through explaining the “big picture” to him in various ways, and taking his feedback, I think I’ve now got a good way of communicating it. Voting. It’s a “real life analogy” which is always dangerous – don’t think of it too literally – I’m not claiming that it’s meant to be an absolute 1:1 correspondence. However, … Continue reading "Push" LINQ revisited – next attempt at an explanation

Last post about the book (nearly) and a new source of information…

By jonskeet

It’s about time I stopped using this blog to mention the book every couple of posts. Fortunately, I now have a new blog of sorts – well, a news page with an RSS feed. It’s part of the book’s web site – completely independent of Manning’s page for the book (which includes a link to their forum for it). The web site is present in skeletal form – there are placeholders for everything I currently intend to include there, but none of the real content yet. That will be the work of the next couple of months. The book itself … Continue reading Last post about the book (nearly) and a new source of information…