Blogs

Donn Felker recently blogged about a neat little extension method in LINQ called Any() .  If you simply want to know if a sequence contains any elements, many people use ".Count() > 0" which will walk the entire sequence to compute the count whereas .Any() will stop walking as soon as it finds a single element.  Easy and much more efficient. It reminded me about another LINQ method I've used from time to time: ToDictionary().  This method will allow you to quickly create a dictionary from any IEnumerable<T>.  Let's start with some sample data that is in a List<T>: IList<Person> people = new List<Person> { new Person {FirstName = "Bob" , LastName = "Smith" , SSN = "1" }, new Person {FirstName = "Jane" , LastName = "Doe" , SSN = "2" }, new Person {FirstName = "Mike" , LastName = "Johnson" , SSN = "3" } }; Converting this to a dictionary is pretty trivial without LINQ.  Suppose we want to index these by SSN: var d = new Dictionary< string , Person>(); foreach (var p in people) { d.Add(p.SSN, p); } But why waste our time doing all that when we can simply use LINQ's ToDictionary()?  Just give it a lambda that selects the key and you're all set: var indexedBySSN = people.ToDictionary(k => k.SSN); Or perhaps you don't want the entire Person object.  Maybe you just want a collection of last names indexed by Social Security Number (SSN).  No problem --there's an overload that accepts two lambdas: one to select the key and one to select the value. var lastNamesIndexedBySSN = people.ToDictionary(k => k.SSN, e => e.LastName); There's also two more overloads that work the same as the two above, but allow you to also provide an IEqualityComparer<T> used to compare your keys. Everyday I find more and more stuff in LINQ that helps me eliminate the mundane code and make my source more readable. Technorati Tags: .NET , LINQ

Eric Gunnerson has a post in which he responds to Justin Etheredge regarding “Is Programming A Generic Skill?” I’ll just say that I agree with them both. There are differences between ability, proficiency and mastery. A Java programmer can jump into C# and be an able C# programmer immediately. It will take time to become proficient and [...]

F.cs(334,8): error CS0539: ‘I.M’ in explicit interface declaration is not a member of interface F.cs(20,15): error CS0535: ‘C’ does not implement interface member ‘I.M(out string)’ This is a fun example of a poor error message, and I don’t mean because I named my file F, my interface I, my method M [...]

The number one feature that has been in Opera for longer than I can remember, and in Firefox via add-in or by default for nearly as long, is that of restoring a session when the browser or system crashes. I lean on this feature. I use browser tabs as a todo list. Sometimes I have to-read [...]