implicit-conversion

问题 I ran into a problem this week regarding implicit conversions in C# on collections. While this (using implicit ) may not be our final approach, I wanted to at least finish out the code to offer the team as an option. I boiled down the problem to the following sample case: I have two classes in my example: one that represents a business object (Foo) and one that represents the client version (View Object) of this business item (FooVO), as defined below... public class Foo { public string Id

问题 This question already has answers here : Closed 8 years ago . Possible Duplicate: Implicit VS Explicit Conversion What is the difference between "implicit conversion" and "explicit conversion"? Is the difference different in Java and C++? 回答1: An explicit conversion is where you use some syntax to tell the program to do a conversion. For example (in Java): int i = 999999999; byte b = (byte) i; // The type cast causes an explicit conversion b = i; // Compilation error!! No implicit conversion

问题 This question already has answers here : Closed 8 years ago . Possible Duplicate: Implicit VS Explicit Conversion What is the difference between "implicit conversion" and "explicit conversion"? Is the difference different in Java and C++? 回答1: An explicit conversion is where you use some syntax to tell the program to do a conversion. For example (in Java): int i = 999999999; byte b = (byte) i; // The type cast causes an explicit conversion b = i; // Compilation error!! No implicit conversion

问题 I'm trying to port my application to Scala 2.10.0-M2. I'm seeing some nice improvements with better warnings from compiler. But I also got bunch of errors, all related to me mapping from Enumeration.values . I'll give you a simple example. I'd like to have an enumeration and then pre-create bunch of objects and build a map that uses enumeration values as keys and then some matching objects as values. For example: object Phrase extends Enumeration { type Phrase = Value val PHRASE1 = Value("My

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

问题 While trying to use a function template that calls a class's specialized static function template it is failing to convert its parameter from the template parameter list. Here is the function that I'm calling in main: template<class Engine, typename Type, template<typename = Type> class Distribution, class... DistParams> Type randomGenerator( RE::SeedType seedType, std::size_t seedValue, std::initializer_list<std::size_t> list, DistParams... params ) { static Type retVal = 0; static Engine

问题 Swift can infer int literals to be doubles or floats let x: Float = 3 It even works with arithmetic. It will convert everything before doing the math, so this is also 3: let y: Float = 5/2 + 0.5 But what are the actual rules for this? There are ambiguous situations, for example if the inference is for a parameter: func foobar(_ x: Int) -> Int { return x } func foobar(_ x: Float) -> Float { return y } foobar(1/2) In this case it infers it as an int and returns 0, but if you delete the first

问题 I'm defining some Scala implicits to make working with a particular unchangeable set of Java classes easier. The following Scala code is a simplified example that obviously looks crazy, in the real world I'm trying to grab particular resources (rather than numeric age) implicitly from the Monkey, Tree & Duck for use in various methods like purchaseCandles() : // actually 3 Java classes I can not change: case class Monkey(bananas: Int) case class Tree(rings: Int) case class Duck(quacks: Seq

问题 Trying out the implicit conversion of TupleN proposed by @Alexey Romanov in How to apply implicit conversions between tuples? Given the following implicits: object ImplicitConversions { object A { implicit def toA(x: Int): A = A(x) } case class A(v: Int) extends AnyVal implicit def liftImplicitTuple2[A, B, A1, B1](tuple: (A, B)) (implicit f1: A => A1, f2: B => B1): (A1, B1) = (f1(tuple._1), f2(tuple._2)) } and the Tuple (1,2) , I can manually apply liftImplicitTuple2 and have it invoke the A

问题 I'm trying to delay evaluation for a bit, and so I prefer to work with functions as long as possible. I have class Function which defines composition and pointwise arithmetics for functions: from functools import reduce def compose(*funcs): ''' Compose a group of functions f1, f2, f3, ... into (f1(f2(f3(...)))) ''' result = reduce(lambda f, g: lambda *args, **kaargs: f(g(*args, **kaargs)), funcs)) return Function(result) class Function: ''' >>> f = Function(lambda x : x**2) >>> g = Function