Angular-如何访问注释类方法

我有以下角度注释声明:

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

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

我想在组件内部使用注释:

@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,因为此方法在编译期间未知。但是,当我在模板中使用相同的方法调用时,它就会工作。也就是说,原型被分配了。

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?