implicit

问题 I was under the impression that context bounds would work only on methods: trait Target[T] class Post { def pinTo[T : Target](t:T) } apparently context bounds can be used in class (and presumably trait ) too: trait Target[T] class Post[T:Target] { def pintTo[T](t:T) } Now I'm confused as to how the evidence can be provided to Post ? class Business implicit object ev extends Target[Business] // is implicit necessary here ? val p = new Post[Business] // ?? how do I provide ev ? related to

问题 I am trying to create an implicit conversion from any type (say, Int) to a String... An implicit conversion to String means RichString methods (like reverse) are not available. implicit def intToString(i: Int) = String.valueOf(i) 100.toCharArray // => Array[Char] = Array(1, 0, 0) 100.reverse // => error: value reverse is not a member of Int 100.length // => 3 An implicit conversion to RichString means String methods (like toCharArray) are not available implicit def intToRichString(i: Int) =

问题 Is there a way to implicitly add methods in scala object? Upd: For example, Unfiltered scala library have singleton object Body which contains methods Body.string(req: HttpRequest) and Body.bytes(req: HttpRequest) for read body from http request. So, I want read body in my domain objects, like Body.cars(req:HttpRequest) . 回答1: import scala.language.implicitConversions object ObjA object ObjB { def x = 1 } object Main { implicit def fromObjA(objA: ObjA.type) = ObjB def main(args: Array[String]

问题 I want to use java.time.LocalDate and java.time.LocalDateTime with an implicit Ordered like: val date1 = java.time.LocalDate.of(2000, 1, 1) val date2 = java.time.LocalDate.of(2010, 10, 10) if (date1 < date2) ... import scala.math.Ordering.Implicits._ doesn't work, because LocalDate inherits from Comparable<ChronoLocalDate> instead of Comparable<LocalDate> . How can I write my own imlicit Orderd to use <, <=, >, >= operators/methods to compare LocalDate 's? Edit: I found a way with use of an

问题 I want to use java.time.LocalDate and java.time.LocalDateTime with an implicit Ordered like: val date1 = java.time.LocalDate.of(2000, 1, 1) val date2 = java.time.LocalDate.of(2010, 10, 10) if (date1 < date2) ... import scala.math.Ordering.Implicits._ doesn't work, because LocalDate inherits from Comparable<ChronoLocalDate> instead of Comparable<LocalDate> . How can I write my own imlicit Orderd to use <, <=, >, >= operators/methods to compare LocalDate 's? Edit: I found a way with use of an

问题 Guys, I have started to work on selenium web driver. You can assume I am a beginner. At the moment I am having difficulties in implementing the implicit wait command in my code (C#). it is not working as it should and result in an exception due to Element not found, however when I add the "Thread.Sleep(3000) the code get executed flawlessly. I have been looking for the solution all over the internet but not able to resolve the problem. Below I have mentioned sample code. class Entrypoint {

问题 Why when i use this: int a = 1; methodWithParamString(a + ""); a is cast to String, bu i can't use toString() on integer? int a = 1; methodWithParamString(a.toString()); Doesn't this: a+"" works like: a.toString() + "" ? 回答1: No, it works like String.valueOf( a ) + "" , which in turn behaves like new StringBuilder( String.valueOf( a ) ).append( "" ).toString() . The important thing to know is that it's all just done by the compiler, in other words it's syntactic sugar. This is why adding

问题 i'm wondering why linkers can not do their job simply by consulting the information in the actual .dll files that got the actual implementation code ? i mean why linkers still need .lib files to do implicit linking ? are not the export and relative address tables enough for such linking ? is there anyway by which one can do implicit linking using only the .dll without the .lib stub/proxy files ? i thought the windows executable loader would simply do LoadLibrary/LoadLibraryEx calls on behalf

问题 Suppose we have implicit parameter lookup concerning only local scopes: trait CanFoo[A] { def foos(x: A): String } object Def { implicit object ImportIntFoo extends CanFoo[Int] { def foos(x: Int) = "ImportIntFoo:" + x.toString } } object Main { def test(): String = { implicit object LocalIntFoo extends CanFoo[Int] { def foos(x: Int) = "LocalIntFoo:" + x.toString } import Def._ foo(1) } def foo[A:CanFoo](x: A): String = implicitly[CanFoo[A]].foos(x) } In the above code, LocalIntFoo wins over

问题 The use cases for implicit macros is supposed to be the so-called "materialisation" of type class instances. Unfortunately, the example in the documentation is a bit vague on how that is achieved. Upon being invoked, the materializer can acquire a representation of T and generate the appropriate instance of the Showable type class. Let's say I have the following trait ... trait PrettyPrinter[T]{ def printed(x:T) : String } object PrettyPrinter{ def pretty[T](x:T)(implicit pretty:PrettyPrinter