如何使泛型类型约束实例化

Question

我有这两个代码片段，我如何改变它们，使MemberModel可以作为泛型类型传入，并保持可实例化，以便我可以提取以下方法到它自己的导出函数?

export interface IFollowable {
    follow(user: IUserModel): IMemberModel;
}
export class CardModel implements ICardModel, IFollowable {
    public follow(user: IUserModel): IMemberModel {
        let member = new MemberModel({userId: user.id});
        member.role = UserRoles.follower;
        this.members.push(member);
        return member;
    }
}

我如何使follow和followable泛型，以便我传入的任何类型保持可更新，就像MemberModel现在一样?

Answer 1

使我传入的任何类型都是可更新的，就像现在的MemberModel一样

因为typescript泛型在编译时被擦除，所以你需要显式地传递它们，例如使用工厂，如下所示:

type User = {name:string};
type Member = {name: string};
type MemberCreator = {new (user:User): Member};
interface Followable {
    follow(user: User, memberCreator: MemberCreator): Member;
}
export class CardModel implements Followable {
    public follow(user: User, memberCreator: MemberCreator): Member {
       return new memberCreator(user);
    }
}