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Formatter (#51)

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Enforce consistent formatting use `dprint`
This commit is contained in:
Luca Palmieri
2024-05-24 17:00:03 +02:00
committed by GitHub
parent 537118574b
commit 99591a715e
157 changed files with 1057 additions and 1044 deletions
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22
book/src/04_traits/09_from.md
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@@ -20,13 +20,13 @@ impl Ticket {
}
```
We've also seen that string literals (such as `"A title"`) are of type `&str`.
We have a type mismatch here: a `String` is expected, but we have a `&str`.
We've also seen that string literals (such as `"A title"`) are of type `&str`.\
We have a type mismatch here: a `String` is expected, but we have a `&str`.
No magical coercion will come to save us this time; we need **to perform a conversion**.
## `From` and `Into`
The Rust standard library defines two traits for **infallible conversions**: `From` and `Into`,
The Rust standard library defines two traits for **infallible conversions**: `From` and `Into`,
in the `std::convert` module.
```rust
@@ -39,7 +39,7 @@ pub trait Into<T>: Sized {
}
```
These trait definitions showcase a few concepts that we haven't seen before: **supertraits** and **implicit trait bounds**.
These trait definitions showcase a few concepts that we haven't seen before: **supertraits** and **implicit trait bounds**.
Let's unpack those first.
### Supertrait / Subtrait
@@ -78,7 +78,7 @@ pub trait From<T: Sized>: Sized {
```
In other words, _both_ `T` and the type implementing `From<T>` must be `Sized`, even
though the former bound is implicit.
though the former bound is implicit.
### Negative trait bounds
@@ -94,23 +94,23 @@ pub struct Foo<T: ?Sized> {
This syntax reads as "`T` may or may not be `Sized`", and it allows you to
bind `T` to a DST (e.g. `Foo<str>`). It is a special case, though: negative trait bounds are exclusive to `Sized`,
you can't use them with other traits.
you can't use them with other traits.
## `&str` to `String`
In [`std`'s documentation](https://doc.rust-lang.org/std/convert/trait.From.html#implementors)
you can see which `std` types implement the `From` trait.
In [`std`'s documentation](https://doc.rust-lang.org/std/convert/trait.From.html#implementors)
you can see which `std` types implement the `From` trait.\
You'll find that `String` implements `From<&str> for String`. Thus, we can write:
```rust
let title = String::from("A title");
```
We've been primarily using `.into()`, though.
We've been primarily using `.into()`, though.\
If you check out the [implementors of `Into`](https://doc.rust-lang.org/std/convert/trait.Into.html#implementors)
you won't find `Into<&str> for String`. What's going on?
`From` and `Into` are **dual traits**.
`From` and `Into` are **dual traits**.\
In particular, `Into` is implemented for any type that implements `From` using a **blanket implementation**:
```rust
@@ -129,7 +129,7 @@ we can write `let title = "A title".into();`.
## `.into()`
Every time you see `.into()`, you're witnessing a conversion between types.
Every time you see `.into()`, you're witnessing a conversion between types.\
What's the target type, though?
In most cases, the target type is either: