Typescript 通用 class 在 object

Question

I want to do a generic typescript class. But it doesn't work when the class is inside an object. I've tried a lot of codes, but they don't work for me:(

I have tried all of this.

// this is my class object
const obj1 = {
    Foo: class<T> {
        foo: T

        constructor({ foo }: { foo: T }) {
            this.foo = foo;
        }

        getFoo(): T {
            return this.foo
        }

        setFoo(t: T): T {
            this.foo = t
            return this.foo
        }
    }
}


// This works: it is typechecked
let a = new obj1.Foo({ foo: 0 })
a.getFoo()      // number
a.setFoo('123') // error


// None of this works
// uncomment them to see errors

// let b: obj1.Foo                                      = new obj1.Foo({ foo: 0 })
// let b: obj1.Foo<number>                              = new obj1.Foo({ foo: 0 })
// let b: typeof obj1.Foo                               = new obj1.Foo({ foo: 0 })
// let b: typeof obj1.Foo<number>                       = new obj1.Foo({ foo: 0 })
// let b: typeof obj1.Foo.prototype                     = new obj1.Foo({ foo: 0 })
// let b: typeof obj1.Foo.prototype<number>             = new obj1.Foo({ foo: 0 })
// let b: typeof obj1["Foo"]["prototype"]               = new obj1.Foo({ foo: 0 })
// let b: typeof obj1["Foo"]["prototype"]<number>       = new obj1.Foo({ foo: 0 })


b.getFoo()      // any
b.setFoo('123') // works (it should error instead)

typescript playground link

thanks but sorry for bad english

Answer 1

That's how you can do what you want:

namespace customNamespace {
    export class Foo<T> {
        private foo: T;

        constructor({ foo }: { foo: T }) {
            this.foo = foo;
        }

        getFoo(): T {
            return this.foo;
        }

        setFoo(t: T): T {
            this.foo = t;
            return this.foo;
        }
    }
}

// This works: it is typechecked
let a = new customNamespace.Foo({ foo: 0 });
a.getFoo();      // number
a.setFoo('123'); // error


// None of the following are typechecked
// uncomment them to see errors

// let b: obj1.Foo                                      = new obj1.Foo({ foo: 0 })
let b: customNamespace.Foo<number>                              = new customNamespace.Foo({ foo: 0 });
// let b: typeof obj1.Foo                               = new obj1.Foo({ foo: 0 })
// let b: typeof obj1.Foo<number>                       = new obj1.Foo({ foo: 0 })
// let b: typeof obj1.Foo.prototype                     = new obj1.Foo({ foo: 0 })
// let b: typeof obj1.Foo.prototype<number>             = new obj1.Foo({ foo: 0 })
// let b: typeof obj1["Foo"]["prototype"]               = new obj1.Foo({ foo: 0 })
// let b: typeof obj1["Foo"]["prototype"]<number>       = new obj1.Foo({ foo: 0 })


b.getFoo()      // old: any, now: typechecked!
b.setFoo('123') // old: works (it should error instead), now: got an error!