打字稿中枚举声明中的方括号的含义是什么?

2024-06-20

我正在浏览一个名为 Angular ngrx 项目的打字稿文件collection.ts在那里,我看到声明了以下枚举常量。

import { Action } from '@ngrx/store';
import { Book } from '../models/book';

export enum CollectionActionTypes {
  AddBook = '[Collection] Add Book',
  AddBookSuccess = '[Collection] Add Book Success',
  AddBookFail = '[Collection] Add Book Fail',
  RemoveBook = '[Collection] Remove Book',
  RemoveBookSuccess = '[Collection] Remove Book Success',
  RemoveBookFail = '[Collection] Remove Book Fail',
  Load = '[Collection] Load',
  LoadSuccess = '[Collection] Load Success',
  LoadFail = '[Collection] Load Fail',
}

/**
 * Add Book to Collection Actions
 */
export class AddBook implements Action {
  readonly type = CollectionActionTypes.AddBook;

  constructor(public payload: Book) {}
}

export class AddBookSuccess implements Action {
  readonly type = CollectionActionTypes.AddBookSuccess;

  constructor(public payload: Book) {}
}

export class AddBookFail implements Action {
  readonly type = CollectionActionTypes.AddBookFail;

  constructor(public payload: Book) {}
}

/**
 * Remove Book from Collection Actions
 */
export class RemoveBook implements Action {
  readonly type = CollectionActionTypes.RemoveBook;

  constructor(public payload: Book) {}
}

export class RemoveBookSuccess implements Action {
  readonly type = CollectionActionTypes.RemoveBookSuccess;

  constructor(public payload: Book) {}
}

export class RemoveBookFail implements Action {
  readonly type = CollectionActionTypes.RemoveBookFail;

  constructor(public payload: Book) {}
}

/**
 * Load Collection Actions
 */
export class Load implements Action {
  readonly type = CollectionActionTypes.Load;
}

export class LoadSuccess implements Action {
  readonly type = CollectionActionTypes.LoadSuccess;

  constructor(public payload: Book[]) {}
}

export class LoadFail implements Action {
  readonly type = CollectionActionTypes.LoadFail;

  constructor(public payload: any) {}
}

export type CollectionActions =
  | AddBook
  | AddBookSuccess
  | AddBookFail
  | RemoveBook
  | RemoveBookSuccess
  | RemoveBookFail
  | Load
  | LoadSuccess
  | LoadFail;

为枚举常量提供一个值很好,但我很困惑这是什么意思[Collection]此处表示为每个常量的一部分。这样的写法对枚举常量的值没有影响还是显示了其他的东西?谁能解释一下吗?


您可能正在使用一些 Flux/Redux 框架,例如ngrx store或类似的。这个枚举定义了动作并确保你的动作键(字符串)在全局级别上是唯一的,因为最后,它们都被合并到减速器反应的一大组动作中。 为了帮助满足该条件,您通常会将操作的类型放在方括号中的键开头。它只是一个命名约定,与打字稿没有任何关系。

例如,

你可以有实体Book and Category。对于他们两个,你都可以用 key 进行操作Load Entity。为了区分这两个操作键,一种约定是将名称命名为[Book] Load Entity and [Category] Load Entity.

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