英文:
Missing lifetime specifier when returning Vec<Vec<&str>> of strings from a file
问题
Here's the translated code part without the error message:
pub fn ParseWords() -> Vec<Vec<&str>> {let file = File::open("./words.txt".to_string()).unwrap();let mut words = Vec::new();// Iterate over the lines of the file.for line in io::BufReader::new(file).lines() {words.push(line.unwrap().split("|").collect::<Vec<&str>>());}// Do a bit of shuffling.let mut rng = thread_rng();words.shuffle(&mut rng);return words.clone();}
英文:
I am trying to write a function that iterates over a text file line by line and splits the sentences into a vector. Then those split lines are put in another vector and returned.
use std::fs::File;use std::io::{ self, BufRead };use rand::seq::SliceRandom;use rand::thread_rng;pub fn ParseWords() -> Vec<Vec<&str>> {let file = File::open("./words.txt".to_string()).unwrap();let mut words = Vec::new();// Iterate over the lines of the file.for line in io::BufReader::new(file).lines() {words.push(line.unwrap().split("|").collect::<Vec<&str>>());}// Do a bit of shuffling.let mut rng = thread_rng();words.shuffle(&mut rng);return words.clone()}
I have went down a rabbit hole putting in the compiler's suggestions and consulted chatgpt but I am not really getting anywhere. When compiling I'm getting this:
error[E0106]: missing lifetime specifier--> src\parser.rs:8:32|8 | pub fn ParseWords() -> Vec<Vec<&str>> {| ^ expected named lifetime parameter|= help: this function's return type contains a borrowed value, but there is no value for it to be borrowed fromhelp: consider using the `'static` lifetime|8 | pub fn ParseWords() -> Vec<Vec<&'static str>> {|
答案1
得分: 2
每当一个函数的参数中没有生命周期，并且返回非静态生命周期时，几乎肯定存在某种问题。你可能唯一会看到这种情况是在 Box::leak 中，它用于泄漏内存。但这里不适用。
所以，你需要返回拥有所有权的值。&str 的拥有版本是 String，所以函数返回值变为 Vec<Vec<String>>。
然后，你需要更改你的迭代器以创建字符串。
line.unwrap().split('|').map(|s| s.to_string()).collect()
清理其他所有内容，我们得到：
pub fn parse_words() -> Vec<Vec<String>> {let file = File::open("./words.txt").unwrap();// 遍历文件的各行。let mut words: Vec<Vec<_>> = io::BufReader::new(file).lines().map(|line| line.unwrap().split('|').map(|s| s.to_string()).collect()).collect();// 做一些混洗。let mut rng = thread_rng();words.shuffle(&mut rng);words}
英文:
Whenever a function has no lifetimes in its arguments and returns a non-static lifetime, you're almost certainly doing something wrong. The only time you're likely to see it is in Box::leak, which is used to leak memory. That's not applicable here.
So, you need to return owned values. The owned version of &str is String, so the function return becomes Vec<Vec<String>>.
Then you need to change your iterator to make strings.
line.unwrap().split('|').map(|s| s.to_string()).collect()
Cleaning up everything else, we get:
pub fn parse_words() -> Vec<Vec<String>> {let file = File::open("./words.txt").unwrap();// Iterate over the lines of the file.let mut words: Vec<Vec<_>> = io::BufReader::new(file).lines().map(|line| line.unwrap().split('|').map(|s| s.to_string()).collect()).collect();// Do a bit of shuffling.let mut rng = thread_rng();words.shuffle(&mut rng);words}
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