将选项或结果向量仅转换为成功值时，如何避免拆封?

问题描述

我有一个Vec<Result<T, E>>，我想忽略所有Err值，将其转换为Vec<T>.我可以这样做:

vec.into_iter().filter(|e| e.is_ok()).map(|e| e.unwrap()).collect()

这是安全的，但我想避免使用unwrap.有没有更好的方法来写这个?

解决方案

因为 Result实现了IntoIterator ，您可以将Vec转换为迭代器(将是迭代器的迭代器)，然后将其展平:

• Iterator::flatten :

  vec.into_iter().flatten().collect()
  

• Iterator::flat_map :

  vec.into_iter().flat_map(|e| e).collect()
  

这些方法也可用于 Option ， 也实现了IntoIterator ./p>

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您还可以将Result转换为Option并使用 Iterator::filter_map :

vec.into_iter().filter_map(|e| e.ok()).collect()

I have a Vec<Result<T, E>> and I want to ignore all Err values, converting it into a Vec<T>. I can do this:

vec.into_iter().filter(|e| e.is_ok()).map(|e| e.unwrap()).collect()

This is safe, but I want to avoid using unwrap. Is there a better way to write this?

解决方案

Since Result implements IntoIterator, you can convert your Vec into an iterator (which will be an iterator of iterators) and then flatten it:

• Iterator::flatten:

  vec.into_iter().flatten().collect()
  

• Iterator::flat_map:

  vec.into_iter().flat_map(|e| e).collect()
  

These methods also work for Option, which also implements IntoIterator.

---

You could also convert the Result into an Option and use Iterator::filter_map:

vec.into_iter().filter_map(|e| e.ok()).collect()

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