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Formatter (#51)

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Enforce consistent formatting use `dprint`
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Luca Palmieri
2024-05-24 17:00:03 +02:00
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parent 537118574b
commit 99591a715e
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book/src/05_ticket_v2/05_nullability.md
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# Nullability
Our implementation of the `assigned` method is fairly blunt: panicking for to-do and done tickets is far from ideal.
Our implementation of the `assigned` method is fairly blunt: panicking for to-do and done tickets is far from ideal.\
We can do better using **Rust's `Option` type**.
## `Option`
`Option` is a Rust type that represents **nullable values**.
`Option` is a Rust type that represents **nullable values**.\
It is an enum, defined in Rust's standard library:
```rust
@@ -15,10 +15,10 @@ enum Option<T> {
}
```
`Option` encodes the idea that a value might be present (`Some(T)`) or absent (`None`).
`Option` encodes the idea that a value might be present (`Some(T)`) or absent (`None`).\
It also forces you to **explicitly handle both cases**. You'll get a compiler error if you are working with
a nullable value and you forget to handle the `None` case.
This is a significant improvement over "implicit" nullability in other languages, where you can forget to check
a nullable value and you forget to handle the `None` case.\
This is a significant improvement over "implicit" nullability in other languages, where you can forget to check
for `null` and thus trigger a runtime error.
## `Option`'s definition
@@ -27,11 +27,11 @@ for `null` and thus trigger a runtime error.
### Tuple-like variants
`Option` has two variants: `Some(T)` and `None`.
`Some` is a **tuple-like variant**: it's a variant that holds **unnamed fields**.
`Option` has two variants: `Some(T)` and `None`.\
`Some` is a **tuple-like variant**: it's a variant that holds **unnamed fields**.
Tuple-like variants are often used when there is a single field to store, especially when we're looking at a
"wrapper" type like `Option`.
Tuple-like variants are often used when there is a single field to store, especially when we're looking at a
"wrapper" type like `Option`.
### Tuple-like structs
@@ -51,7 +51,7 @@ let y = point.1;
### Tuples
It's weird say that something is tuple-like when we haven't seen tuples yet!
It's weird say that something is tuple-like when we haven't seen tuples yet!\
Tuples are another example of a primitive Rust type.
They group together a fixed number of values with (potentially different) types: