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Update guide to reflect the removal of specialization in impl Responder for Result.

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`Result<T, E>` only implements `Responder` if both `T` and `E` implement
`Responder`.
This commit is contained in:
Lucille Blumire 2021-01-22 18:43:21 +00:00 committed by Jeb Rosen
parent 0c5e184299
commit a2fa4296a0
1 changed files with 8 additions and 12 deletions
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20
site/guide/5-responses.md
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@ -237,15 +237,15 @@ async fn files(file: PathBuf) -> Option<NamedFile> {
### `Result`
`Result` is a special kind of wrapping responder: its functionality depends on
whether the error type `E` implements `Responder`.
`Result` is another _wrapping_ responder: a `Result<T, E>` can only be returned
when `T` implements `Responder` and `E` implements `Responder`.
When the error type `E` implements `Responder`, the wrapped `Responder` in `Ok`
or `Err`, whichever it might be, is used to respond to the client. This means
that the responder can be chosen dynamically at run-time, and two different
kinds of responses can be used depending on the circumstances. Revisiting our
file server, for instance, we might wish to provide more feedback to the user
when a file isn't found. We might do this as follows:
The wrapped `Responder` in `Ok` or `Err`, whichever it might be, is used to
respond to the client. This means that the responder can be chosen dynamically
at run-time, and two different kinds of responses can be used depending on the
circumstances. Revisiting our file server, for instance, we might wish to
provide more feedback to the user when a file isn't found. We might do this as
follows:
```rust
# #[macro_use] extern crate rocket;
@ -262,10 +262,6 @@ async fn files(file: PathBuf) -> Result<NamedFile, NotFound<String>> {
}
```
If the error type `E` _does not_ implement `Responder`, then the error is simply
logged to the console, using its `Debug` implementation, and a `500` error is
returned to the client.
## Rocket Responders
Some of Rocket's best features are implemented through responders. You can find