如何在typescript中的泛型类中的type参数中创建一个新对象？ [英] How to create a new object from type parameter in generic class in typescript?

问题描述

我试图在泛型类中创建一个类型参数的新对象。
在我的类View中，我有2个作为类型参数传递的泛型类型的对象列表，但是当我尝试使新的TGridView（） typescript 找不到符号'TGridView'...

这是代码：

  module AppFW {
 //代表一个视图
 export class View< TFormView extends FormView，TGridView extends GridView> {
 //表格列表
 public Forms：{[idForm：string]：TFormView; } = {}; 
 
 //网格列表
 public Grids：{[idForm：string]：TGridView; } = {}; 
 $ b $ public AddForm（formElement：HTMLFormElement，dataModel：any，submitFunction ?:（e：SubmitFormViewEvent）=> boolean）：FormView {
 var newForm：TFormView = new TFormView（formElement，dataModel ，submitFunction）; 
 this.Forms [formElement.id] = newForm; 
返回newForm; 
 
 $ b $ public AddGrid（element：HTMLDivElement，gridOptions：any）：GridView {
 var newGrid：TGridView = new TGridView（element，gridOptions）; 
 this.Grids [element.id] = newGrid; 
返回newGrid; 
 
 
 
 $ $ $ 
 $ b我可以从一个通用类型？
解决方案
因为编译后的JavaScript会删除所有类型信息，所以不能使用 
 
 
 
您可以通过将类型传递给构造函数以非泛型方式来完成此操作。
 > 
 
 
  class TestOne {
 hi（）{
 alert（'Hi'）; 
 
 
 
 class TestTwo {
构造函数（private testType）{
 
} 
 getNew（）{
返回new this.testType（）; 
} 
} 
 
 var test = new TestTwo（TestOne）; 
 
 var example = test.getNew（）; 
 example.hi（）; 
  
你可以使用泛型来扩展这个例子来收紧类型：
 
 
  class TestBase {
 hi（）{
 alert（'Hi from base'）; 
 
 
 
 class TestSub extends TestBase {
 hi（）{
 alert（'Hi from sub'）; 
} 
} 
 
 class TestTwo< T扩展TestBase> {
 constructor（private testType：new（）=> T）{
} 
 
 getNew（）：T {
 return new this.testType（）; 
} 
} 
 
 // var test = new TestTwo< TestBase>（TestBase）; 
 var test = new TestTwo< TestSub>（TestSub）; 
 
 var example = test.getNew（）; 
 example.hi（）; 
  
 
I'm trying to create a new object of a type parameter in my generic class.
In my class "View" I have 2 list of objects of generic type passed as type parameters, but when I try to make new TGridView() typescript says Could not find symbol 'TGridView'...

This is the code:
module AppFW {
    // Represents a view
    export class View<TFormView extends FormView, TGridView extends GridView> {
        // The list of forms 
        public Forms: { [idForm: string]: TFormView; } = {};

        // The list of grids
        public Grids: { [idForm: string]: TGridView; } = {};

        public AddForm(formElement: HTMLFormElement, dataModel: any, submitFunction?: (e: SubmitFormViewEvent) => boolean): FormView {
            var newForm: TFormView = new TFormView(formElement, dataModel, submitFunction);
            this.Forms[formElement.id] = newForm;
            return newForm;
        }

        public AddGrid(element: HTMLDivElement, gridOptions: any): GridView {
            var newGrid: TGridView = new TGridView(element, gridOptions);
            this.Grids[element.id] = newGrid;
            return newGrid;
        }
    }
}
Can I create objects from a generic type?
解决方案
Because the compiled JavaScript has all the type information erased, you can't use T to new up an object.

You can do this in a non-generic way by passing the type into the constructor.
class TestOne {
    hi() {
        alert('Hi');
    }
}

class TestTwo {
    constructor(private testType) {

    }
    getNew() {
        return new this.testType();
    }
}

var test = new TestTwo(TestOne);

var example = test.getNew();
example.hi();
You could extend this example using generics to tighten up the types:
class TestBase {
    hi() {
        alert('Hi from base');
    }
}

class TestSub extends TestBase {
    hi() {
        alert('Hi from sub');
    }
}

class TestTwo<T extends TestBase> {
    constructor(private testType: new () => T) {
    }

    getNew() : T {
        return new this.testType();
    }
}

//var test = new TestTwo<TestBase>(TestBase);
var test = new TestTwo<TestSub>(TestSub);

var example = test.getNew();
example.hi();


                        
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