foundenum`std::option::Option`|=note:expected type`&str`found type`std::option::Option<&str>`=help:here are some functions which might fulfill your needs:-.unwrap()-.unwrap_or_default()error:aborting due to previous
比较简单,如果一个 trait 没有定义任何方法,那么就是空 trait。 traitAnimal{}structDog{ name:String, }// 尽管 Animal 没有定义任何方法,也必须要显式地指定实现某个 trait// 需要注意:如果想为 Dog 定义方法,那么需要单独写一个 impl 块// 比如为 Dog 实现 eat 方法,那么 eat 方法就不能写在当前的块...
1、创建OsString从 Rust 字符串创建：OsString 实现 From<String>，因此您可以使用 my_string.From 从...
AI代码解释 use thiserror::Error;#[derive(Error,Debug)]#[non_exhaustive]pubenumDataStoreError{#[error("data store disconnected")]Disconnect(#[from]io::Error),#[error("the data for key `{0}` is not available")]Redaction(String),#[error("invalid header (expected {expected:?}, found {fou...
pub enum DataStoreError { Disconnect(io::Error), Redaction(String), InvalidHeader { expected: String, found: String }, Unknown, } impl std::fmt::Display for DataStoreError { fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result { match self { DataStoreError::Disconne...
【Rust每周一知】Rust为什么会有String和&str?!长文预警! 本文是Amos博客文章“Working with strings in Rust”的翻译。 原文地址:https://fasterthanli.me/blog/2020/working-with-strings-in-rust/ 人们选择Rust编程语言时总会遇到一个问题:为什么会有两种字符串类型?为什么会出现String和&str?
fn next(&mut self) -> Option<T>; } 1. 2. 3. 它们的区别主要在于: 一个特定类型(比如上文中的 Cat)可以多次实现泛型 trait。比如对于 From,可以有 impl From<&str> for Cat 也可以有 impl From<String> for Cat ...
expected struct `std::string::String`, found integer help: try using a conversion method: `5.to_string()` Closure至少实现了Fn, FnMut和FnOnce三种traits之中的一个。如果不需要创建Closure上下文中的变量,能传Closure的地方也能传Function 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19...
error[E0308]: mismatched types --> src/main.rs:8:20 | 8 | take_str_maybe(option); | ^^^ expected `str`, found struct `String` | = note: expected enum `Option<&str>` found enum `Option<&String>` For more information about this error, try `rustc --explain E0308`. error: co...
hir().node_to_string(node_id), DefId::local(hir_id.owner), local_id_root) }); } } else { // We use "Null Object" TypeckTables in some of the analysis passes. // These are just expected to be empty and their `local_id_root` is // `None`. Therefore we cannot verify ...