implicit

Passing Slick 2.0 implicit session in elegant way

由 会有一股神秘感。 提交于 2019-12-09 23:06:18
问题 I'm new to Slick and Scala. First of take a look at my example table with case class mapping and helper for queries SuitsManager . Now methods of SuitsManager are called by Play! controllers inside DBAction (I'm using play-slick 0.6.0.1). package models import play.api.db.slick._ import play.api.db.slick.Config.driver.simple._ import scala.collection.immutable.HashMap import scala.slick.jdbc.JdbcBackend case class Suit(id:Option[Long], complainant: String, defender: String, litigation: Long,

ASP.NET: explicit vs implicit localization?

由 ぃ、小莉子 提交于 2019-12-09 17:41:18
问题 To my mind the advantage of implicit localization over explicit localization is that if you have more than one property to localize for a given control, it's a more economical syntax. In the case where you just need to localize some text I use the asp:Localize control which only has a single property (Text) that renders to the UI. Is there a reason to use one over the other? Any style preference? Are there any speed differences? Implicit <asp:Localize ID="Localize1" runat="server" meta

Are implicit operators and TypeConverters equivalent?

由 邮差的信 提交于 2019-12-09 15:03:14
问题 It seems to me its very easy to implement an implicit operator versus a TypeConverter, so I'm assuming they aren't equivalent because of the prevalence of TypeConverters in the framework (see anything that extends FrameworkElement). But why? Wouldn't it have been much easier to create string->object and object->string implicit operators and take advantage of those in serialization (both XML and XAML)? Is it YAGNI? Single responsibility? Because you can't specify operator overloads in

Implicit Template Parameters

由 限于喜欢 提交于 2019-12-09 05:16:50
问题 The following code generates a compile error in Xcode: template <typename T> struct Foo { Foo(T Value) { } }; int main() { Foo MyFoo(123); return 0; } error: missing template arguments before 'MyFoo' Changing Foo MyFoo(123); to Foo<int> MyFoo(123); fixes the issue, but shouldn't the compiler be able to figure out the appropriate datatype? Is this a compiler bug, or am I misunderstanding implicit template parameters? 回答1: The constructor could in theory infer the type of the object it is

solution of an implicit equation with fzero on MATLAB

由 主宰稳场 提交于 2019-12-08 19:28:26
I've been trying to solve this implicit equation by using fzero in MATLAB. File that holds the code is named as "colebrook" and I've typed so far is as below. D = input('Please enter the pipe diameter in meters: '); V = input('Please enter the fluid velocity in m/s: '); rho = input('Please enter fluid density in kg/m^3: '); mew = input('Please enter fluid viscosity in kg/m*s: '); Re = D*V*rho/mew; eps = input('Enter absolute roughness in milimeters: '); eD = eps/(D*1000); a = fzero(colebrookfunc,0.1); fprintf(a); Equation that I want to solve is kept in another m-file called "colebrookfunc" ,

How does Scala use explicit types when resolving implicits?

由 烈酒焚心 提交于 2019-12-08 17:45:37
问题 I have the following code which uses spray-json to deserialise some JSON into a case class, via the parseJson method. Depending on where the implicit JsonFormat[MyCaseClass] is defined (in-line or imported from companion object), and whether there is an explicit type provided when it is defined, the code may not compile. I don't understand why importing the implicit from the companion object requires it to have an explicit type when it is defined, but if I put it inline, this is not the case?

Play Framework JSON Fails With Ordering

由 老子叫甜甜 提交于 2019-12-08 13:43:09
问题 I have a huge set of case classes where below is just a subset of these case classes: sealed trait BuiltInType { def id: Int } case class ZombieType (a: String, id: Int = 0) extends BuiltInType case class BooleanType (a: Boolean, id: Int = 1) extends BuiltInType case class ByteType (a: Byte, id: Int = 2) extends BuiltInType case class UByteType (a: Byte, id: Int = 3) extends BuiltInType case class Int16Type (a: Int, id: Int = 4) extends BuiltInType case class UInt16Type (a: Int, id: Int = 5)

Implicitly Typed vs Anonymous Type

由 大兔子大兔子 提交于 2019-12-08 00:49:38
问题 Is it same or any difference between Implicitly Typed and Anonymous Type.If it is different so What is the main difference between Implicitly Typed and Anonymous Type? 回答1: There is a huge difference: Implicitly typed (local) variables, are variables which type is not explicitly given: var i = new StringBuilder(); Now, i is implicitly of type StringBuilder - a named type. Anonymous types on the other side do not have a name, they are anonymous : var x = new { Foo = "Bar" }; x is now of an

Implicit Conversions on Generic Trait

由 你离开我真会死。 提交于 2019-12-08 00:13:27
问题 I am implementing a datastructure and want the user to be able to use any type as key as long as he provides a suitable key type wrapping it. I have a trait for this key type. The idea is to have implicit conversions from base to key type and the other way round to (virtually) just use the base type. The trait looks like this: trait Key[T] extends Ordered[Key[T]] { def toBase : T // Further stuff needed for datastructure... } object Key { implicit def key2base[T](k : Key[T]) : T = k.toBase }

scala: pimp my library with overloads

由 与世无争的帅哥 提交于 2019-12-07 23:37:21
问题 Any ideas why doesn't the following work? implicit def listExtensions[A](xs : List[A]) = new ListExtensions(xs) class ListExtensions[A](xs : List[A]) { def foreach[B](f: (A, Int) => B) { var i = 0; for (el <- xs) { f(el, i); i += 1; } } } var a = List(1, 2, 3); a foreach { (el, i) => println(el, i) }; When I compile this with fsc 2.8.1, I get the following error: "wrong number of parameters; expected = 1: a foreach { (el, i) => println(el, i) };". Am I doing something wrong or there simply
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