func

I am wondering if this is a sane choice of key for a dictionary? What I want to do is use an expression as the key in a dictionary, something like: var map3 = new Dictionary<Func<int, bool>, int>(); map3.Add((x) => x % 2 == 0, 1); map3.Add((x) => x % 10 == 0, 2); // ... var key = map3.Keys.SingleOrDefault(f => f(2)); // key = (x) => x % 2 // map3[key] = 1 The idea being this is a cleaner way than having big if-else or switch statements. Does this make sense? Will it work? Is there an simpler way? Mike Zboray No, C# constructs a new delegate instance whenever a lambda is used so you wouldn't be

My morbid curiosity has me wondering why the following fails: // declared somewhere public delegate int BinaryOperation(int a, int b); // ... in a method body Func<int, int, int> addThem = (x, y) => x + y; BinaryOperation b1 = addThem; // doesn't compile, and casting doesn't compile BinaryOperation b2 = (x, y) => x + y; // compiles! C# has very limited support for "structural" typing. In particular, you can't cast from one delegate-type to another simply because their declarations are similar. From the language specification: Delegate types in C# are name equivalent, not structurally

I have Go program that has a function defined. I also have a map that should have a key for each function. How can I do that? I have tried this, but this doesn't work. func a(param string) { } m := map[string] func { 'a_func': a, } for key, value := range m { if key == 'a_func' { value(param) } } Are you trying to do something like this? I've revised the example to use varying types and numbers of function parameters. package main import "fmt" func f(p string) { fmt.Println("function f parameter:", p) } func g(p string, q int) { fmt.Println("function g parameters:", p, q) } func main() { m :=

All the examples I can find about Func<> and Action<> are simple as in the one below where you see how they technically work but I would like to see them used in examples where they solve problems that previously could not be solved or could be solved only in a more complex way, i.e. I know how they work and I can see they are terse and powerful , so I want to understand them in a larger sense of what kinds of problems they solve and how I could use them in the design of applications. In what ways (patterns) do you use Func<> and Action<> to solve real problems? using System; using System

I'm trying to "share" a set of conditions between a Linq to Entities call and a some other code, to reduce possible mismatches in conditions between the two calls. I started off by declaring my conditions: private Func<DateTime, Status, bool> _submissionDateExpiredCondition = (submissionDate, status) => submissionDate < DateTime.Now && status == Status.OK; private Func<DateTime, Status, bool> _submissionDateWithinOneWeekCondition = (submissionDate, status) => DateTime.Now < DbFunctions.AddDays(submissionDate, -7) && status == Status.Pending; private Func<DateTime?, Status, bool>

I am trying to run a function in certain ViewController using AppDelegate func applicationDidBecomeActive(_ application: UIApplication) { ViewController().grabData() } But somehow the function does not seem to run at all when the app has become active after entering the app from the background. The function looks like this func grabData() { self._DATASERVICE_GET_STATS(completion: { (int) -> () in if int == 0 { print("Nothing") } else { print(int) for (_, data) in self.userDataArray.enumerated() { let number = Double(data["wage"]!) let x = number!/3600 let z = Double(x * Double(int)) self.money

In the below example, how can I easily convert eventScores to List<int> so that I can use it as a parameter for prettyPrint ? Console.WriteLine("Example of LINQ's Where:"); List<int> scores = new List<int> { 1,2,3,4,5,6,7,8 }; var evenScores = scores.Where(i => i % 2 == 0); Action<List<int>, string> prettyPrint = (list, title) => { Console.WriteLine("*** {0} ***", title); list.ForEach(i => Console.WriteLine(i)); }; scores.ForEach(i => Console.WriteLine(i)); prettyPrint(scores, "The Scores:"); foreach (int score in evenScores) { Console.WriteLine(score); } You'd use the ToList extension: var