以我的经验，在进入动作中很少需要这些函数，所以这一方法不会使得用户代码太过难看。

In my experience, these functions are needed only rarely in entry actions so this workaround should not uglify user code too much.

youdao

在状态进入和退出时可能执行其他动作。

Additional actions may be performed on state entry and exit.

youdao

缓存后的页面和动作都会进入公共目录。

Both cached pages and actions go into the public directory.

youdao