extension-methods

Situation is pretty simple - I wrote an extension method and made it async with return type Task<T> . But when I try to call it using await, compiler throws an error which suggests that the extension method wasn't recognized as async at all. Here's my code: public static async Task<NodeReference<T>> CreateWithLabel<T>(this GraphClient client, T source, String label) where T: class { var node = client.Create(source); var url = string.Format(ConfigurationManager.AppSettings[configKey] + "/node/{0}/labels", node.Id); var serializedLabel = string.Empty; using (var tempStream = new MemoryStream())

The following program does not compile, because in the line with the error, the compiler chooses the method with a single T parameter as the resolution, which fails because the List<T> does not fit the generic constraints of a single T . The compiler does not recognize that there is another method that could be used. If I remove the single- T method, the compiler will correctly find the method for many objects. I've read two blog posts about generic method resolution, one from JonSkeet here and another from Eric Lippert here , but I could not find an explanation or a way to solve my problem.

I have the following code in a playground file: extension Dictionary { func test() { for key in self.keys { self[key] } } } var dict: [String: AnyObject?] = [ "test": nil ] dict.test() I will henceforth refer to the line within the for-each loop as the output since it is what's relevant. In this particular instance the output is nil . When I change the for-each loop to look like this: for key in self.keys { print(self[key]) } The output is "Optional(nil)\n" . What I really want to do is check the value for nil, but the code: for key in self.keys { self[key] == nil } outputs false . One other

Everyone knows and love String.IsNullOrEmpty(yourString) method. I was wondering if it's going to confuse developers or make code better if we extend String class to have method like this: yourString.IsNullOrEmpty(); Pro: More readable. Less typing. Cons: Can be confusing because yourString variable can be null and it looks like you're executing method on a null variable. What do you think? The same question we can ask about myObject.IsNull() method. That how I would write it: public static class StringExt { public static bool IsNullOrEmpty(this string text) { return string.IsNullOrEmpty(text)

From previous experience I had been under the impression that it's perfectly legal (though perhaps not advisable) to call extension methods on a null instance. So in C#, this code compiles and runs: // code in static class static bool IsNull(this object obj) { return obj == null; } // code elsewhere object x = null; bool exists = !x.IsNull(); However, I was just putting together a little suite of example code for the other members of my development team (we just upgraded to .NET 3.5 and I've been assigned the task of getting the team up to speed on some of the new features available to us),