Types 重载构造函数时的类型问题

我在重载构造函数时遇到问题，它不会让我告诉它变量包含什么类型。我怎样才能强制一个类型，或使它无论如何工作

constructor(points: Point[], name?: string);
constructor(walls: Wall[], name?: string);
constructor(pointsOrWalls: (Wall | Point)[], name?: string) {
    if (pointsOrWalls[0] instanceof Point) {
        //  If first is Point all must be Points

        //  But here typescript says that pointsOrWalls is of type (Wall | Point)[]
        this.walls = pointsOrWalls.map(function(point, ind, points) {
            return new Wall(point, points[++ind % points.length])
        })
    }else{
        //  Since these aren't points they are Walls
        this.walls = walls
    }
    this.name = name
}

我怎样才能强制一个类型，或者让这个工作无论如何

使用类型断言：

//  If first is Point all must be Points
let points = pointsOrWalls as Point[];

完成：

class Wall {w}
class Point {p}

class Foo {
    walls;
    name
    constructor(points: Point[], name?: string);
    constructor(walls: Wall[], name?: string);
    constructor(pointsOrWalls: (Wall | Point)[], name?: string) {
        if (pointsOrWalls[0] instanceof Point) {
            //  If first is Point all must be Points
            let points = pointsOrWalls as Point[];

            //  But here typescript says that pointsOrWalls is of type (Wall | Point)[]
            this.walls = points.map(function(point, ind, points) {
                return new Wall(point, points[++ind % points.length])
            })
        }else{
            //  Since these aren't points they are Walls
            this.walls = walls
        }
        this.name = name
    }   
}

更多

我怎样才能强制一个类型，或者让这个工作无论如何

使用类型断言：

//  If first is Point all must be Points
let points = pointsOrWalls as Point[];

完成：

class Wall {w}
class Point {p}

class Foo {
    walls;
    name
    constructor(points: Point[], name?: string);
    constructor(walls: Wall[], name?: string);
    constructor(pointsOrWalls: (Wall | Point)[], name?: string) {
        if (pointsOrWalls[0] instanceof Point) {
            //  If first is Point all must be Points
            let points = pointsOrWalls as Point[];

            //  But here typescript says that pointsOrWalls is of type (Wall | Point)[]
            this.walls = points.map(function(point, ind, points) {
                return new Wall(point, points[++ind % points.length])
            })
        }else{
            //  Since these aren't points they are Walls
            this.walls = walls
        }
        this.name = name
    }   
}

更多

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虽然这很好，但有没有办法不重新声明变量？你可以创建一个用户定义的类型guardDon不明白，什么guard？@Akxe我刚刚为你写了文档：非常感谢，这绝对值得加入书签尽管这很好，有没有办法不重新声明变量？你可以创建一个用户定义的类型guardDon不明白，什么guard？@Akxe我刚刚为你写了文档：非常感谢，这绝对值得放在书签里