如何在打字稿中的类方法上强制执行函数类型接口？

Question

我隐式编写的许多方法都class具有相同的函数类型。我想要做的是强制执行此函数类型，以便我可以明确声明某些方法必须符合该函数类型。

例如

interface MyFunctionType {(resource: string | Resource): Something}

我的类有一些符合这个接口的方法。

class MyClass {
    // ...

    someMethod() { /*...*/ }

    someMethodThatConforms(resource: string | Resource) {
        // ...
        return new Something(/*...*/);
    }

    anotherMethodThatConforms(resource: string | Resource) {
        // ...
        return new Something(/*...*/);
    }

    someOtherMethod() { /*...*/ }

    // ...
}

我知道这一点someMethodThatConforms并anotherMethodThatConforms符合接口，但现在我想知道如何断言这一点someMethodThatConforms并且anotherMethodThatConforms必须符合接口MyFunctionType（这样如果我更改，MyFunctionType就会引发错误）？

Answer 1

如果您不想创建另一个界面，这是另一种方法

interface MyFunctionType {(resource: string | Resource): Something}

class MyClass {
    // ...

    someMethod() { /*...*/}

    public someMethodThatConforms: MyFunctionType = (resource: string | Resource) => {
        // ...
        return new Something(/*...*/);
    }

    public anotherMethodThatConforms: MyFunctionType = (resource: string | Resource) => {
        // ...
        return new Something(/*...*/);
    }

    someOtherMethod() { /*...*/}

    // ...
}

Answer 2

我们可以定义另一个接口并MyClass实现它：

interface MyFunctionType {(resource: string | Resource): Something}

interface FixedMethods {
    someMethodThatConforms: MyFunctionType;
    // you can add more
}

class MyClass implements FixedMethods {
    someMethodThatConforms(resource: string | Resource) {
        // this method will fail type check, until we return a Something
        return 1;
    }
}

更复杂的方式：使用mapped type创建泛型类型：

interface MyFunctionType { (resource: string | Resource): Something }

// a Mapped Type to fix methods, used in place of a interface
type FixedMethods<T extends string> = {
    [k in T]: MyFunctionType
}

class MyClass implements FixedMethods<"someMethodThatConforms" | "anotherMethodThatConforms"> {
    someMethodThatConforms(resource: string | Resource) {
        // this method will fail type check, until we return a Something
        return 1;
    }

    // it also complains about lack of "anotherMethodThatConforms" method
}