The advent of Action and Func family of delegates has rendered custom delegates less used, but the latter still finds uses. Advantages of custom delegates include: As others have pointed, conveys intent clearly unlike generic Action and Func (Patrik has a very good point about meaningful parameter names). You can specify ref/out parameters unlike the … Read more
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 := map[string]interface{}{ “f”: f, “g”: … Read more
Are you familiar with delegates in general? I have a page about delegates and events which may help if not, although it’s more geared towards explaining the differences between the two. Func<T, TResult> is just a generic delegate – work out what it means in any particular situation by replacing the type parameters (T and … Read more
You’re going to need a function to produce random CGFloats in the range 0 to 1: extension CGFloat { static func random() -> CGFloat { return CGFloat(arc4random()) / CGFloat(UInt32.max) } } Then you can use this to create a random colour: extension UIColor { static func random() -> UIColor { return UIColor( red: .random(), green: … Read more
There’s no difference at all. The second is just a shorthand for Invoke, provided by the compiler. They compile to the same IL.
Ooh, it’s not easy at all. Func<T> represents a generic delegate and not an expression. If there’s any way you could do so (due to optimizations and other things done by the compiler, some data might be thrown away, so it might be impossible to get the original expression back), it’d be disassembling the IL … Read more
Predicate: essentially Func<T, bool>; asks the question “does the specified argument satisfy the condition represented by the delegate?” Used in things like List.FindAll. Action: Perform an action given the arguments. Very general purpose. Not used much in LINQ as it implies side-effects, basically. Func: Used extensively in LINQ, usually to transform the argument, e.g. by … Read more
ref and out are not part of the type parameter definition so you can’t use the built-in Func delegate to pass ref and out arguments. Of course, you can declare your own delegate if you want: delegate V MyDelegate<T,U,V>(T input, out U output);
Please read “How to Write Go Code”. Use go build or go install within the package directory, or supply an import path for the package. Do not use file arguments for build or install. While you can use file arguments for go run, you should build a package instead, usually with go run ., though … Read more
While Predicate has been introduced at the same time that List<T> and Array<T>, in .net 2.0, the different Func and Action variants come from .net 3.5. So those Func predicates are used mainly for consistency in the LINQ operators. As of .net 3.5, about using Func<T> and Action<T> the guideline states: Do use the new … Read more