TypeScript:使用动态导入的工厂模式不允许构造对象的新实例以进行合成

问题描述 投票:0回答:1

我正在使用动态导入在Typescript中实现工厂模式,以便我可以初始化负载,在运行时初始化(具有必要的组合)所需模块。

我能够像https://www.typescriptlang.org/docs/handbook/release-notes/typescript-2-4.html一样动态加载模块

但是它不允许我初始化加载的模块。虽然在开发人员控制台中我可以进行初始化,甚至可以通过初始化模块中组成的子模块和类来无缝地组合它。

苦苦挣扎找到这个解决方案并试了很多东西,但没有解决。在C#中,我们可以使用反射创建它,并创建库和类的实例作为延迟加载而不直接引用它们。

我得到的错误是“//不能使用'new'与表达式类型缺少调用或构造signature.ts(2351)”当我做的时候

let y: Interfaces.IComponent =  new comp(); 

构造它并将其分配给varebale,该对象的接口类型正在实现。

对于组件正在扩展的父类类型也是如此

let x: ComponentImpl =  new comp();

请看下面的打字稿代码。

    import { Interfaces } from 'shared';
    import { ComponentImpl } from 'core';

    export default class Factory {
        private _loadedModules: Map<string, Interfaces.IComponent> = new Map<string, Interfaces.IComponent>();
        private static _instace: Factory;

        private constructor() {

        }

        public static get Instance(): Factory {
            return this._instace || (this._instace = new this());
        }

        public getComponent(component: string): Promise<Interfaces.IComponent> {
            return new Promise<Interfaces.IComponent>(async (resolve, reject) => {
                let comp = this._loadedModules.get(component);
                if (comp !== null) {
                    comp = await import(`./${component}`);
                    if (comp) {

// ----------------------------------------------------------------------------
                        // ** NOTE: On run time I can see the module is loaded corrctly and I can initialze its sub classes in developer console.
                        // like controller = new comp.controller(); (get console log from constructor)
                        // controller.sayHello();
                        // controller.setAPIInstance(new comp.getAPI());
                        // controller.saveToAPI();
                        let y: Interfaces.IComponent =  new comp(); // Cannot use 'new' with an expression whose type lacks a call or construct signature.ts(2351)
                        let x: ComponentImpl =  new comp(); // Cannot use 'new' with an expression whose type lacks a call or construct signature.ts(2351)
                        this._loadedModules.set(component, comp);


                        resolve(comp);
                    } else {
                        reject("Unable lo load module");
                    }
                } else {
                    setTimeout(() => {
                        resolve(comp);
                    }, 1);
                }

            });
        }
    }
javascript webpack factory-pattern ts-loader dynamic-import
1个回答
0
投票

您可以尝试以下适用于我的案例的解决方案:

let x: ComponentImpl =  new (comp as typeof ComponentImpl )()

另请参阅TypeScript中的此票证:https://github.com/Microsoft/TypeScript/issues/2081

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