javascript - 是否可能 Async Await - 流畅的构建器方法

Question

这是我的成长之路:回调、promise、async/await。我记得一个模式——流畅的构建器，看起来更像解释器。我想将 async/await 与解释器混合。是否可以？我觉得不可能。但我可以准确地定义原因。 我有:

  after(async () => {
    await shellContainer.uninstall()
    await shellContainer.dispose()
  })

我感兴趣的是:

after(async () => {
    await shellContainer
      .uninstall()
      .dispose()
  })

问候。

Answer 1

为了分离关注点，您可以引入专用的 builder它实现了流畅的界面。

这样你只需要从最终的 build 返回一个 promise 方法，让事情变得简单很多。

以下是一个相当粗糙但实用的示例:

class ShellContainer
{
  uninstall() {
    return new Promise(resolve => {
      setTimeout(() => {
        console.log('uninstalled');
        resolve();
      }, 400 + Math.random() * 600);
    });
  }

  dispose() {
    return new Promise(resolve => {
      setTimeout(() => {
        console.log('disposed');
        resolve();
      }, 400 + Math.random() * 600);
    });
  }
}

class ShellContainerBuilder
{
  container;
  plan;

  constructor() {
    this.reset();
  }

  reset() {
    this.container = new ShellContainer();
    this.plan = () => Promise.resolve();
  }

  stage(op) {
    this.plan = ((prev) => () => prev().then(op))(this.plan);
  }

  uninstall() {
    this.stage(() => this.container.uninstall());
    return this;
  }

  dispose() {
    this.stage(() => this.container.dispose());
    return this;
  }

  build() {
    return this.plan().then(() => this.container);
  }
}

(async () => {
  console.log('starting w/o builder:');
  const shellContainer1 = new ShellContainer();
  await shellContainer1.uninstall();
  await shellContainer1.dispose();
  console.log('w/o builder done.');

  console.log('starting w/ builder:');
  const shellContainer2 = await (new ShellContainerBuilder()).uninstall().dispose().build();
  console.log(shellContainer2);
  console.log('w/ builder done.');
})();