Result

ResultOption 相似,但表示操作成功或失败,且每个操作的类型不同。这类似于表达式练习中定义的 Res,但是一个泛型:Result<T, E>,其中 T 用于 Ok 变体,E 出现在 Err 变体中。

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Speaker Notes

This slide should take about 10 minutes.
  • Option 方法相同,成功值位于 Result 方法内部, 开发者必须显示提取成功值。因此,建议进行错误检查。在绝不应出现错误的情况下, 可以调用 unwrap()expect() 方法,这也是一种开发者意向信号。
  • Result documentation is a recommended read. Not during the course, but it is worth mentioning. It contains a lot of convenience methods and functions that help functional-style programming.
  • Result is the standard type to implement error handling as we will see on Day 4.