optional-parameters

I'm new to iOS development and I understand that allowing optional values when an object is initialized is not a 'good citizen' technique. That being said, I've read that it is good practice to always have values set, like this: class Item{ var name: String var color: String init(name: String, color: String) { self.name = name self.color = color } } This looks nice and tidy but how can I do something like that working with Firebase? Look what I've got so far: private func loadPosts(){ databaseHandle = ref.child("users/\(self.user.uid)/posts").observe(.value, with:{(snapshot) in var newPosts =

I have a web application with lots of data, and a search/filter function with several fields, such as name, status, date, and so on. I have been using parameterized queries like this for the regular (non-search) queries: $id = $_POST['itemID']; $db = mysqli_connect($host, $username, $password, $database); $sql_query = "SELECT * FROM tbl_data WHERE ID = ?"; $stmt_query = mysqli_prepare($db, $sql_query); mysqli_stmt_bind_params($stmt_query, "i", $id); mysqli_stmt_execute($stmt_query); //and so on.. How would I protect agains SQL-injection with multiple, optional parameters? There can be up to 10

I can: scala> def foo( f: => String) = println(f) foo: (f: => String)Unit and I can: scala> def foo( f: String*) = f.map(println) foo: (f: String*)Seq[Unit] but I can't: scala> def foo( f: =>String* ) = f.map(println) <console>:1: error: ')' expected but identifier found. def foo( f: =>String* ) = f.map(println) ^ nor scala> def foo( f: (=>String)* ) = f.map(println) <console>:1: error: no by-name parameter type allowed here def foo( f: (=>String)* ) = f.map(println) ^ Is there some other way to do what I want? Why isn't this allowed? Here the => means that the parameter is passed by name.

Say, we have ClassA with method Foo containing an optional parameter. So, we can use it as shown in method DoFoo . public class ClassA { public ClassA() { } public void Foo(bool flag = true) { } public void DoFoo() { Foo(); // == Foo(true); } } Once I needed to pass it to another class ClassB . First I tried to pass it as Action , but the signature surely didn't match. Then I passed it as Action<string> , the signature matched, but the parameter in ClassB was no longer optional. But I did wanted to have it optional and came to an idea to declare a delegate. So, it worked. public delegate void