Log_Err

是 log crate 的小型扩展，它提供了两个方法用于 core::result::Result<T, E> 和 core::option::Option<T>

log_except 和 log_unwrap，在解包/期望 Result/Option 的同时，还会调用 log::error! 宏（在 Result::Err/Option::None 的情况下）。

缩写为

something().map_err(|e| error!("{}: {:?}", msg, e)).expect(msg)

示例

let mut file = File::create("foo.txt").log_expect("Error creating file");

# Error will be logged with the error! macro
[ERROR] Error creating file: Os { code: 2, kind: NotFound, message: "No such file or directory" }

# Main program panic'ing with same message
thread 'main' panicked at 'Error creating file: Os { code: 2, kind: NotFound, message: "No such file or directory" }', test.rs:4:48