实现可索引的接口 [英] Implement an indexible interface

问题描述

我将如何实现可索引的接口:

How would I implement an interface that is indexible:

interface fooInterface{
    // indexable
    [index:string]:number;
    [index:number]:number;          
}


class Foo implements fooInterface{
    // What goes here? 
}

推荐答案

你永远不会在类定义中实现它，而只是通过寻址 instance[index]，所以你的 fooInterface 不能通过 implements 在 TypeScript 类上使用，但可以用于描述对象的预期结构，例如var foo: fooInterface = {};

You don't ever implement it in the class definition, but only by addressing instance[index], so your fooInterface cannot be be used via implements on a TypeScript class, but can be used to describe the expected structure of an object, e,g. var foo: fooInterface = {};

描述可索引对象

JavaScript 中的一个常见模式是使用对象(例如 {})作为从一组字符串映射到一组值.当这些值是相同的类型，您可以使用接口来描述索引到一个对象总是产生某种类型的值(在这种情况下，小部件).

A common pattern in JavaScript is to use an object (e.g. {}) as way to map from a set of strings to a set of values. When those values are of the same type, you can use an interface to describe that indexing into an object always produces values of a certain type (in this case, Widget).

interface WidgetMap {
    [name: string]: Widget;
}

var map: WidgetMap = {};
map['gear'] = new GearWidget();
var w = map['gear']; // w is inferred to type Widget

引用和小部件示例取自:http://blogs.msdn.com/b/typescript/archive/2013/01/24/interfaces-walkthrough.aspx

Quote and Widget example taken from: http://blogs.msdn.com/b/typescript/archive/2013/01/24/interfaces-walkthrough.aspx

这篇关于实现可索引的接口的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！