Generics Typescript调用泛型类型的静态方法
我有一个服务,我想用它从JSON返回一个指定类型的对象 我有一个类Generics Typescript调用泛型类型的静态方法,generics,typescript,service,static,Generics,Typescript,Service,Static,我有一个服务,我想用它从JSON返回一个指定类型的对象 我有一个类MyClass,它实现了一个静态类,定义了一个FromJSON静态方法 export interface InterfaceMyClass { static FromJSON(json: any): any; } export class MyClass implements InterfaceMyClass { constructor(){} FromJSON(json: any): MyClass
MyClass
,它实现了一个静态类,定义了一个FromJSON
静态方法
export interface InterfaceMyClass {
static FromJSON(json: any): any;
}
export class MyClass implements InterfaceMyClass {
constructor(){}
FromJSON(json: any): MyClass {
let instance = MyClass.create(MyClass.prototype);
Object.assign(instance, json);
// Some other code specific to MyClass
return instance;
}
}
我不知道如何调用我在服务中传入参数的泛型类的静态方法。
我的服务如下所示:
export class MyService<T extends InterfaceMyClass> {
getObject() {
let json = getExternalJson(...);
return T.FromJSON(json); // <-- How to call static method FromJSON from T class ?
}
}
有几件事:
(1) 接口不能有静态声明,例如:
interface MyInterface {
static myMethod(); // Error: 'static' modifier cannot appear on a type member
}
class MyClass<T extends string> {
private member: T;
constructor() {
this.member = new T(); // Error: Cannot find name 'T'
}
}
()
在typescript中解决此问题的方法是定义一个生成器/构造函数接口:
interface MyInterface {}
interface MyInterfaceBuilder {
new (): MyInterface;
myMethod();
}
(2) 泛型约束仅在编译时可用,但编译器会删除它们,因为javascript不支持它,例如:
interface MyInterface {
static myMethod(); // Error: 'static' modifier cannot appear on a type member
}
class MyClass<T extends string> {
private member: T;
constructor() {
this.member = new T(); // Error: Cannot find name 'T'
}
}
()
当查看js输出时,很清楚为什么编译器抛出找不到名称“T”
错误,因为T
找不到
要解决所有这些问题,这里有一个解决方案:
interface IMyClass {}
interface IMyClassBuilder<T extends IMyClass> {
new (): T;
FromJSON(json: any): any;
}
class MyClass implements IMyClass {
static FromJSON(json: any) {
return "";
}
}
class MyService<T extends IMyClass> {
private classToCreate: IMyClassBuilder<T>;
constructor(classToCreate: IMyClassBuilder<T>) {
this.classToCreate = classToCreate;
}
getObject(): T {
let json = getExternalJson(...);
return this.classToCreate.FromJSON(json);
}
}
let service = new MyService(MyClass);
let myObject = service.getObject();
接口IMyClass{}
接口IMyClassBuilder{
新的():T;
FromJSON(json:any):any;
}
类MyClass实现IMyClass{
静态FromJSON(json:any){
返回“”;
}
}
类MyService{
创建私有类:IMyClassBuilder;
构造函数(classToCreate:IMyClassBuilder){
this.classToCreate=classToCreate;
}
getObject():T{
让json=getExternalJson(…);
返回this.classToCreate.FromJSON(json);
}
}
let service=new MyService(MyClass);
让myObject=service.getObject();
()
interface IMyClass {}
interface IMyClassBuilder<T extends IMyClass> {
new (): T;
FromJSON(json: any): any;
}
class MyClass implements IMyClass {
static FromJSON(json: any) {
return "";
}
}
class MyService<T extends IMyClass> {
private classToCreate: IMyClassBuilder<T>;
constructor(classToCreate: IMyClassBuilder<T>) {
this.classToCreate = classToCreate;
}
getObject(): T {
let json = getExternalJson(...);
return this.classToCreate.FromJSON(json);
}
}
let service = new MyService(MyClass);
let myObject = service.getObject();