Question

我需要将String（不是&str）与另一个String分开：

use std::str::Split;

fn main() {
    let x = "".to_string().split("".to_string());
}

为什么我会遇到此错误以及如果我必须对字符串进行操作，如何避免它？

error[E0277]: the trait bound `std::string::String: std::ops::FnMut<(char,)>` is not satisfied
 --> src/main.rs:4:32
  |
4 |         let x = "".to_string().split("".to_string());
  |                                ^^^^^ the trait `std::ops::FnMut<(char,)>` is not implemented for `std::string::String`
  |
  = note: required because of the requirements on the impl of `std::str::pattern::Pattern<'_>` for `std::string::String`

根据#stix-beginners IRC频道，这可能是Deref在1.20.0-夜间失败的一个例子。 How to split a string in Rust?没有解决按String分割的问题，而不是&str。

Answer 1

全部都在documentation。您可以提供以下其中一项：

A &str，
A char，
关闭，

这三种类型实现Pattern特征。您将String提供给split而不是&str。

示例：

fn main() {
    let x = "".to_string();
    let split = x.split("");
}

Answer 2

我和#stix-beginners IRC频道讨论了这个问题并听取了以下内容：

15:12:15           achird | d33tah: split accepts a Pattern, where Pattern can be &str or char, but you're passing a String (no idea why deref is not working)
15:13:01           d33tah | achird: thanks! how can I convert string to str?
15:13:03           achird | i think a simple split(&delimiter2) should fix the problem
15:16:26           calops | why isn't deref working though?
15:21:33        @mbrubeck | calops, d33tah: Deref coercions only work if one exact "expected" type is known.  For a generic type like <P: Pattern>, coercion doesn't kick in.
15:24:11        @mbrubeck | d33tah: The error should definitely be improved...  It should complain that `String` doesn't impl `Pattern`, instead of jumping straight to `FnMut(char)`

基本上，解决方案是添加＆amp;在分隔符字符串之前，如下所示：

fn main() {
    let s1 = "".to_string();
    let s2 = "".to_string();
    let x = s1.split(&s2);
}

尝试拆分字符串时，字符串`FnMut＆lt;（char，）＆gt;`没有为`String`实现

2 个答案: