如何跟踪错误结果的原因？ [英] How to trace the cause of an error result?
问题描述
编写使用 Result 类型的代码时，您可能希望用户和开发人员使用不同的行为。
When writing code that uses Result type, you may want different behavior for users and developers.
- 在编写可以妥善处理错误的应用程序时，最好使用
Result。 - 在开发过程中可能需要可以捕获错误，以查看由哪一行代码创建错误，或者在创建
Err值后获取堆栈跟踪。
- When writing an application that gracefully handles errors, it's nice to use
Result. - During development you may want to "catch" the error to see what line of code creates the error or get a stack-trace the moment the
Errvalue is created.
如果您犯了一个独特的错误，搜索起来并不难，但是如果该错误来自标准库，则该错误可能非常笼统。
If you make a unique error it's not hard to search for it, but if the error is from the standard library, the error may be very generic.
例如，如果不手动更改每个<$ c $，就不可能知道哪个 read 命令导致了意外的文件结尾。 c> file.read（）？到 file.read（）。unwrap（）。
For example, it's impossible to know which read command caused an unexpected end-of-file without manually changing every file.read()? to file.read().unwrap().
是否有一种方便的方法来从 Result 获得堆栈跟踪？
Is there a convenient way to get a stack-trace from a Result?
可行的解决方案可能是创建一个读取宏， read_in_r elease_unwrap_in_debug！（文件，数据） ...但是感觉很尴尬。
A weak but workable solution could be to make a macro for reading, read_in_release_unwrap_in_debug!(file, data)... but this feels very awkward.
I有一个文件读取器，其中有许多 read 调用，但其中一个失败。我不确定哪个。在运行时，我想将结果推回给调用者。对于调试，我希望停止失败的读取调用，或者以某种方式让我知道它的行号。
I have a file reader with many read calls and one fails. I'm not sure which. At run-time, I want to push the result back to the caller. For debugging, I want the failed read call to stop or somehow let me know its line number.
推荐答案
结果本身不会没有任何回溯信息，但是您可以将其添加到自定义错误类型。
A result by itself doesn't have any backtrace information, but you can add it to custom error types.
错误链条板箱是为您生成错误类型的示例，当 RUST_BACKTRACE 时，您可以免费获得错误类型设置了环境变量。
The error_chain crate is an example which generates an error type for you, for which you get backtrace generation for free when the RUST_BACKTRACE environment variable is set.
您还可以使用 backtrace 库，然后自己完成。
You could also use the backtrace library directly and do it yourself.
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