Javascript Angular-如何访问注释类方法

我在Angular中声明了以下注释：

class ModalContainer {
    public destroy: Function;
    public closeModal() {
        this.destroy();
    }
}

export function Modal() {
    return function (target: any) {
        Object.assign(target.prototype, ModalContainer.prototype);
    };
}

我想在组件内使用注释：

@Component({
    selector: 'my-component',
    templateUrl: 'my-component.template.html',
    styleUrls: ['my-component.style.scss']
})
@Modal()
export class MyComponent implements OnInit {
    private EVENT_SAVE = 'EVENT_SAVE';
    private EVENT_CANCEL = 'EVENT_CANCEL';
    private buttonClick(event: any, eventType: string){
        if (eventType === this.EVENT_CANCEL){
            this.closeModal();
        } else if(eventType === this.EVENT_SAVE){
            this.closeModal();
        }
    }
}

问题是，TypeScript无法编译，因为编译时不知道该方法。但是，当我在模板内使用相同的方法调用时，它就可以工作了。也就是说，原型是指定的

编译器显示以下错误消息：

ERROR in [at-loader] ./src/main/webapp/ui/src/my-component.component.ts:128:18
    TS2339: Property 'closeModal' does not exist on type 'MyComponent'.

---

有人知道我怎么能解决这个问题吗？

通过添加这一行，编译器将不再抱怨，并且可以正常工作

private closeModal: Function;

然后，该类将如下所示：

@Component({
    selector: 'my-component',
    templateUrl: 'my-component.template.html',
    styleUrls: ['my-component.style.scss']
})
@Modal()
export class MyComponent implements OnInit {
    private EVENT_SAVE = 'EVENT_SAVE';
    private EVENT_CANCEL = 'EVENT_CANCEL';
    private closeModal: Function;
    private buttonClick(event: any, eventType: string){
        if (eventType === this.EVENT_CANCEL){
            this.closeModal();
        } else if(eventType === this.EVENT_SAVE){
            this.closeModal();
        }
    }
}