typescript 多重继承解决方法
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Multiple inheritance workarounds
提问by Corey Alix
I'm trying to discover a pattern for combining multiple interfaces into one abstract class. Presently I can combine multiple interfaces via implements, but an interface cannot declare a constructor. When I must introduce a constructor I'm forced to use an abstract class. When I use a abstract class I must re-declare the entire composite interface! Surely I'm missing something?
我试图发现一种将多个接口组合成一个抽象类的模式。目前我可以通过 组合多个接口implements，但接口不能声明构造函数。当我必须引入构造函数时，我不得不使用抽象类。当我使用抽象类时，我必须重新声明整个复合接口！我肯定错过了什么吗？
interface ILayerInfo {
a: string;
}
interface ILayerStatic {
b(): string;
}
class Layer implements ILayerInfo, ILayerStatic {
constructor(info: ILayerInfo);
a: string;
b(): string;
}
ANSWER: Use new:
答案：使用new：
interface Layer extends ILayerInfo, ILayerStatic {
new(info: ILayerInfo);
}
// usage: new Layer({ a: "" });
回答by Ryan Cavanaugh
Declaring a constructor on the same interface as the instance members doesn't really make much sense -- if you're going to pass in a type dynamically to use in a constructor, it's the static side of the class that would be restricted. What you would want to do is probably something like this:
在与实例成员相同的接口上声明构造函数并没有多大意义——如果您要动态传入一个类型以在构造函数中使用，那么将受到限制的是类的静态方面。你想要做的可能是这样的：
interface Colorable {
colorize(c: string): void;
}
interface Countable {
count: number;
}
interface ColorCountable extends Colorable, Countable {
}
interface ColorCountableCreator {
new(info: {color: string; count: number}): ColorCountable;
}
class ColorCounted implements ColorCountable {
count: number;
colorize(s: string) { }
constructor(info: {color: string; count: number}) {
// ...
}
}
function makeThings(c: ColorCountableCreator) {
var results: ColorCountable[];
for(var i = 0; i < 10; i++) {
results.push(new c({color: 'blue', count: i}));
}
return results;
}
var items = makeThings(ColorCounted);
console.log(items[0].count);
See also How does typescript interfaces with construct signatures work?
