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Merge pull request #331 from fooofei/master

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ch09-02/map_err 使用错误，对齐英文原文
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KaiserY 2019-08-29 22:09:32 +08:00 committed by GitHub
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src/ch09-02-recoverable-errors-with-result.md
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@ -135,19 +135,19 @@ use std::fs::File;
use std::io::ErrorKind; use std::io::ErrorKind;
fn main() { fn main() {
let f = File::open("hello.txt").map_err(|error| { let f = File::open("hello.txt").unwrap_or_else(|error| {
if error.kind() == ErrorKind::NotFound { if error.kind() == ErrorKind::NotFound {
File::create("hello.txt").unwrap_or_else(|error| { File::create("hello.txt").unwrap_or_else(|error| {
panic!("Tried to create file but there was a problem: {:?}", error); panic!("Problem creating the file: {:?}", error);
}) })
} else { } else {
panic!("There was a problem opening the file: {:?}", error); panic!("Problem opening the file: {:?}", error);
} }
}); });
} }
``` ```
在阅读完第十三章后再回到这个例子，并查看标准库文档 `map_err` 和 `unwrap_or_else` 方法都做了什么操作。还有很多这类方法可以消除大量处理错误时嵌套的 `match` 表达式。 在阅读完第十三章后再回到这个例子，并查看标准库文档 `unwrap_or_else` 方法都做了什么操作。在处理错误时，还有很多这类技巧可以消除大量嵌套的 `match` 表达式。
### 失败时 panic 的简写：`unwrap` 和 `expect` ### 失败时 panic 的简写：`unwrap` 和 `expect`