The type returned by `String::from_utf8(raw)`, is `Result<_>` and needs
to be mapped to match the type of the return type of `next`. You get
this error otherwise:
```
Compiling playground v0.0.1 (/playground)
warning: unused import: `ErrorKind`
--> src/main.rs:1:21
|
1 | use std::io::{self, ErrorKind};
| ^^^^^^^^^
|
= note: `#[warn(unused_imports)]` on by default
error[E0308]: mismatched types
--> src/main.rs:29:17
|
29 | Ok(Some(s))
| ---- ^ expected `String`, found `Result<String, FromUtf8Error>`
| |
| arguments to this enum variant are incorrect
|
= note: expected struct `String`
found enum `Result<String, FromUtf8Error>`
help: the type constructed contains `Result<String, FromUtf8Error>` due to the type of the argument passed
--> src/main.rs:29:12
|
29 | Ok(Some(s))
| ^^^^^-^
| |
| this argument influences the type of `Some`
note: tuple variant defined here
--> /playground/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/core/src/option.rs:579:5
|
579 | Some(#[stable(feature = "rust1", since = "1.0.0")] T),
| ^^^^
help: use the `?` operator to extract the `Result<String, FromUtf8Error>` value, propagating a `Result::Err` value to the caller
|
29 | Ok(Some(s?))
| +
For more information about this error, try `rustc --explain E0308`.
warning: `playground` (bin "playground") generated 1 warning
error: could not compile `playground` (bin "playground") due to 1 previous error; 1 warning emitted
```
The speaker notes suggest an evolution of the code to support a periodic
timer, but the last step was under-specified.
(As mentioned by @fw-immunant and referenced in #1536)
As I mentioned in #1536:
* Break into segments at approximately the places @fw-immunant put
breaks
* Move all of the files into `src/concurrency`
* Add timings and segment/session metadata so course outlines appear
There's room for more work here, including some additional feedback from
@fw-immunant after the session I observed, but let's do one step at a
time :)
