interface

问题 What makes the first implementation KO ? type IToto = abstract Toto : unit -> unit { new IToto with member this.Toto = fun () -> () } { new IToto with member this.Toto () = () } 回答1: In the compile representation, there is a difference between property of a function type, compiled as FSharpFunc<unit, unit> Toto { get; } , and a method taking unit and returning unit, compiled as unit Toto() . The first object expression implements a different interface: type IToto = abstract Toto : (unit ->

问题 I have the following types: type Statement interface { Say() string } type Quote struct { quote string } func (p Quote) Say() string { return p.quote } func Replay(conversation []Statement) { for _, statement := range conversation { fmt.Println(statement.Say()) } } I think I have a fairly good grasp of why a function that accepts a parameter of type []Statement , cannot be called with []Quote ; even though Quote implements Statement , []Quote does not implement []Statement . []Statement is

问题 I'm currently working on an MVC 3 project using Ninject as my DI, the business objects are stored in a separate assembly. I'm running into an issue with the controller parameters, when posting back for CRUD operations I'm getting the error "Cannot create an instance of an interface". I am aware that you can't create an instance of an interface, but it seems like the only way I can get around this is to use a custom model binder and pass the FormCollection through. This seems really messy and

问题 I believe it's pretty stupid, and I am a bit embarrassed to ask this kind of question, but I still could not find the answer: I am looking at the class List<T> , which implemetns IList . public class List<T> : IList one of the methods included in Ilist is int Add(object value) I understand that List<T> should not expose that method (type safety...), and it really does not. But how can it be? mustnt class implement the entire interface? 回答1: I believe that this (interface) method is

问题 For example in the following example: type Food interface { Eat() bool } type vegetable_s struct { //some data } type Vegetable *vegetable_s type Salt struct { // some data } func (p Vegetable) Eat() bool { // some code } func (p Salt) Eat() bool { // some code } Do Vegetable and Salt both satisfy Food , even though one is a pointer and the other is directly a struct? 回答1: The answer is easy to get by compiling the code: prog.go:19: invalid receiver type Vegetable (Vegetable is a pointer type

问题 is there a possibility to create an fmap for records so that I can apply the same function to record fields of similar bur different types Let say I have a record field type Item and a record X and function transform type Item<'a, 'b> = Item of 'a * 'b let transform (i: Item<'a, 'b>) : Item<'a, string> = let (Item (x, y)) = i Item (x, sprintf "%A" y) type X<'a> = { y: Item<'a, int> z: Item<'a, bool> } with member inline this.fmap(f) = { y = f this.y z = f this.z } now the line z = f this.z

问题 I better explain the question with an example. I have an Interface Model which can be used to access data. There can be different implementations of Model which can represent the data in various format say XMl , txt format etc. Model is not concerned with the formats. Lets say one such implementation is myxmlModel . Now i want to force myxmlModel and every other implementation of Model to follow Singleton Pattern .The usual way is to make myxmlModels constructor private and provide a static

问题 I am working on a .NET project, which needs to interact with some user defined classes - reffered to as "jobs". All job classes must implement a specific interface IJob in order order for the library to consume them. Sometimes a job class might hold unmanaged resource, which needs to be explicitly disposed. How should I ensure that all jobs are properly disposed after use, if I do not know in advance if the job needs explicit disposal? I have a few ideas myself, but would like to hear your

问题 For example, (although it's not an interface) the Stream class in .NET has an implementation provided by Stream.Null which simply discards the data. PowerShell has Out-Null. In applications I've developed, I've often found it useful to implement an interface IFoo with a default implementation NullFoo or similar when it is preferable to have a useless implementation rather than not passing an object at all. My question is how should I refer to this practice in documenting or explaining an

问题 Is there a way in PhpStorm to automatically generate the empty methods that are required by the interface the given class is implementing? Say we have an Interface with 3 methods - when defining the new class that implements this interface - some option to auto-generate containers for all required methods. 回答1: From my comment: You could try ALT + ENTER . This normaly shows up a small "dialog" to autogenerate phpdoc, functions, etc. 回答2: Sure, you can. There are 3 ways to do it : Press Ctrl +