在 Typescript 中声明一个委托类型 [英] Declare a delegate type in Typescript

问题描述

来自 C# 背景，我想创建一个定义函数签名的数据类型.在 C# 中，这是一个 delegate 声明如下:

Coming from a C# background, I want to create a datatype that defines a function signature. In C#, this is a delegate declared like this:

delegate void Greeter (string message);

public class Foo
{
    public void SayHi (Greeter g) {
        g("Hi!");
    }
}

现在，我想在 Typescript 中实现类似的功能.我知道 Typescript 没有委托类型，但只有 lambdas.我想出了这样的事情:

Now, I want to achieve similar in Typescript. I know Typescript has no delegate types, but only lambdas. I came up with something like this:

class Foo {
    SayHi (greeter: (msg: String) => void) {
        greeter('Hi!');
    }
}

虽然这可行，但我想重用方法签名 (msg:String) =>void 几次，并认为创建自定义类型会更简洁 - 就像 C# 中的委托一样.

While this works, I want to reuse the method signature (msg:String) => void couple of times and think it would be cleaner to create a custom type - like the delegate in C#.

有什么想法可以做到这一点吗?

Any ideas how this can be done?

推荐答案

在 TypeScript 中，接口可以有调用签名.在您的示例中，您可以这样声明:

In TypeScript, interfaces can have call signatures. In your example, you could declare it like this:

interface Greeter {
    (message: string): void;
}

function sayHi(greeter: Greeter) {
    greeter('Hello!');
}

sayHi((msg) => console.log(msg)); // msg is inferred as string

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