Typings for a "class-based" API approach with workers

workers-rpc-typings.ts

class Users {
    constructor(private env: Env) {}
    
    async getUser(userId: string) {
        // ...
    }
    // ...
}

type PickMatching<T, V> = {
    [K in keyof T as T[K] extends V ? K : never]: T[K];
};
// biome-ignore lint/complexity/noBannedTypes: it's okay here as it is only a picker
type ExtractMethods<T> = PickMatching<T, Function>;

export class Backend extends WorkerEntrypoint<Env> {
    #users: Users;
    constructor(ctx: ExecutionContext, env: Env) {
        super(ctx, env);
        this.#users = new Users(env);
    }

    get users() {
        // biome-ignore format: its nicer in one line
        return {
            getUser: this.#users.getUser.bind(this.#users),
            getUsers: this.#users.getUsers.bind(this.#users),
            createUser: this.#users.createUser.bind(this.#users),
            deleteUser: this.#users.deleteUser.bind(this.#users)
        } satisfies ExtractMethods<Users>
    }
}