为什么 Angular Dart 2 ViewEncapsulation 不再接受枚举？

Question

在 Angular Dart 2 Alpha 35 中，@view 组件接受了一个枚举值：

@View(
  styleUrls: const ["package:tickets/client/components/flight_display/flight_display.css"],
  templateUrl: "package:tickets/client/components/flight_display/flight_display.html",
  directives: const[CORE_DIRECTIVES],
  encapsulation: ViewEncapsulation.NONE
)

封装：ViewEncapsulation.NONE 现在抛出以下错误：

Error:(11, 18) Arguments of a constant creation must be constant
 expressions

问题： 将值从枚举传递到 ViewEncapsulation 对象的推荐方法是什么？

上下文

这是 Angular.Dart 2 库的枚举：

enum ViewEncapsulation {
  /**
   * Emulate scoping of styles by preprocessing the style rules
   * and adding additional attributes to elements. This is the default.
   */
  Emulated,
  /**
   * Uses the native mechanism of the renderer. For the DOM this means creating a ShadowRoot.
   */
  Native,
  /**
   * Don't scope the template nor the styles.
   */
  None
}

Answer 1

在const[CORE_DIRECTIVES]之后少了一个,（由https://github.com/angular/angular/issues/4169#issuecomment-140011891找到），ViewEncapsulation.NONE应该是ViewEncapsulation.None

@View(
  styleUrls: const ["package:tickets/client/components/flight_display/flight_display.css"],
  templateUrl: "package:tickets/client/components/flight_display/flight_display.html",
  directives: const[CORE_DIRECTIVES],
  encapsulation: ViewEncapsulation.None
)

为什么 Angular Dart 2 ViewEncapsulation 不再接受枚举？

Why is Angular Dart 2 ViewEncpasulation no longer accepting enums?

dart

angular-dart

angular