请签名如下:
export interface INotificationService {
error(message: string, title?: string, autoHideAfter?: number);
}
我如何调用函数error()不指定标题参数,但设置autoHideAfter说1000?
请签名如下:
export interface INotificationService {
error(message: string, title?: string, autoHideAfter?: number);
}
我如何调用函数error()不指定标题参数,但设置autoHideAfter说1000?
当前回答
你可以在接口上指定多个方法签名,然后在类方法上重载多个方法:
interface INotificationService {
error(message: string, title?: string, autoHideAfter?: number);
error(message: string, autoHideAfter: number);
}
class MyNotificationService implements INotificationService {
error(message: string, title?: string, autoHideAfter?: number);
error(message: string, autoHideAfter?: number);
error(message: string, param1?: (string|number), param2?: number) {
var autoHideAfter: number,
title: string;
// example of mapping the parameters
if (param2 != null) {
autoHideAfter = param2;
title = <string> param1;
}
else if (param1 != null) {
if (typeof param1 === "string") {
title = param1;
}
else {
autoHideAfter = param1;
}
}
// use message, autoHideAfter, and title here
}
}
现在所有这些都可以工作了:
var service: INotificationService = new MyNotificationService();
service.error("My message");
service.error("My message", 1000);
service.error("My message", "My title");
service.error("My message", "My title", 1000);
...INotificationService的error方法将有以下选项:
操场上
其他回答
您可以创建一个helper方法,该方法根据错误参数接受一个对象参数
error(message: string, title?: string, autoHideAfter?: number){}
getError(args: { message: string, title?: string, autoHideAfter?: number }) {
return error(args.message, args.title, args.autoHideAfter);
}
这与@Brocco的回答几乎相同,但略有不同:只在对象中传递可选参数。(并使params对象可选)。
它最终有点像Python的**kwargs,但又不完全是。
export interface IErrorParams {
title?: string;
autoHideAfter?: number;
}
export interface INotificationService {
// make params optional so you don't have to pass in an empty object
// in the case that you don't want any extra params
error(message: string, params?: IErrorParams);
}
// all of these will work as expected
error('A message with some params but not others:', {autoHideAfter: 42});
error('Another message with some params but not others:', {title: 'StackOverflow'});
error('A message with all params:', {title: 'StackOverflow', autoHideAfter: 42});
error('A message with all params, in a different order:', {autoHideAfter: 42, title: 'StackOverflow'});
error('A message with no params at all:');
在这种情况下,你可以对那些你不想覆盖的可选参数使用“undefined”值
export interface INotificationService {
error(message: string, title?: string, autoHideAfter?: number);
}
你可以调用类似的错误方法
error("it works", undefined, 20);
注意,null在这里不起作用。
在TS中,您还可以将参数设置为Object,并使对象的值可选,这样您就不必定义每个参数,只需定义您想要使用的参数即可。
公共函数beingcalled (obj:{状态?: number,错误?:字符串,消息?:字符串}){ If (obj.message) {console.log(obj.message)} } 这一点。functionBeingCalled({消息:'检测到错误'})
你可以在接口上指定多个方法签名,然后在类方法上重载多个方法:
interface INotificationService {
error(message: string, title?: string, autoHideAfter?: number);
error(message: string, autoHideAfter: number);
}
class MyNotificationService implements INotificationService {
error(message: string, title?: string, autoHideAfter?: number);
error(message: string, autoHideAfter?: number);
error(message: string, param1?: (string|number), param2?: number) {
var autoHideAfter: number,
title: string;
// example of mapping the parameters
if (param2 != null) {
autoHideAfter = param2;
title = <string> param1;
}
else if (param1 != null) {
if (typeof param1 === "string") {
title = param1;
}
else {
autoHideAfter = param1;
}
}
// use message, autoHideAfter, and title here
}
}
现在所有这些都可以工作了:
var service: INotificationService = new MyNotificationService();
service.error("My message");
service.error("My message", 1000);
service.error("My message", "My title");
service.error("My message", "My title", 1000);
...INotificationService的error方法将有以下选项:
操场上