如何从元组转换（option＆lt;＆amp; str＆gt; option＆lt; st str; str＆gt;）tuple（option＆lt; string＆gt; string＆gt; option＆lt string＆gt;）？

Question

我正在尝试从中获取：

let a: Option<&str> = Some("foo");
let b: Option<String> = a.map(|s| s.to_string());

转到元组形式：

let c: (Option<&str>, Option<&str>) = (Some("bar"), Some("baz"));
let d: (Option<String>, Option<String>) = c.map(|s| (s.0.to_string(), s.1.to_string()));

7 |     let d: (Option<String>, Option<String>) = c.map(|s| (s.0.to_string(), s.1.to_string()));
  |                                                 ^^^ `(Option<&str>, Option<&str>)` is not an iterator
  |
  = note: the following trait bounds were not satisfied:
          `(Option<&str>, Option<&str>): Iterator`
          which is required by `&mut (Option<&str>, Option<&str>): Iterator

如何使用Rust 1.61或更新的元组转换为可选字符串的元组？

Answer 1

就像您有两个变量时那样做：

let c = (Some("bar"), Some("baz"));
let d = (c.0.map(|s| s.to_string()), c.1.map(|s| s.to_string()));