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Remove some of the less-commonly-used pattern abilities

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Connects to #115. Not fixes, because I'm going to give some of these
more motivation before I think we can say we've covered what a new
rustacean *needs* to know.

Connects to #114 because I removed the trailing off last section, but I
do want to give this section a real ending.
This commit is contained in:
Carol (Nichols || Goulding) 2016-06-29 21:12:07 -06:00
parent f6e536a1a2
commit cefbd7f16d
1 changed files with 4 additions and 54 deletions
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58
src/ch06-04-patterns.md
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@ -1,9 +1,9 @@
# Patterns # Patterns
We've mentioned 'patterns' a few times so far: they're used in `let` bindings, We've mentioned 'patterns' a few times so far: they're used in `let` bindings,
in function arguments, and in the `match` expression. Patterns have a lot of in function arguments, and in `match` expressions. Patterns have a lot of
abilities, so in this section, we'll cover all of the different things they can abilities, so in this section, we'll cover some of the most commonly used ones.
do. Any of these abilities work in any place where a pattern is used. Any of these abilities work in any place where a pattern is used.
## Literals & _ ## Literals & _
@ -84,52 +84,6 @@ match name {
// than moving it // than moving it
``` ```
## Destructuring
Patterns can be used to destructure structs and enums:
```rust
struct Point {
x: i32,
y: i32,
}
let origin = Point { x: 0, y: 0 };
let Point { x, y } = origin;
```
This brings an `x` and `y` binding into scope, matching the `x` and `y` of
`origin`. While it can be unusual in `let`, this is the same principle of
patterns in `match`:
```rust
struct Point {
x: i32,
y: i32,
}
let origin = Point { x: 0, y: 0 };
match origin {
Point { x, y } => { }, // x and y are bound here
}
```
## Shadowing
As with all bindings, anything bound by a pattern will shadow bindings
outside of the binding construct:
```rust
let x = Some(5);
match x {
Some(x) => { }, // x is an i32 here, not an Option<i32>
None => (),
}
```
## Ignoring bindings ## Ignoring bindings
We discussed using `_` as a whole pattern to ignore it above, but you can We discussed using `_` as a whole pattern to ignore it above, but you can
@ -188,7 +142,7 @@ Ranges are usually used with integers or `char`s:
```rust ```rust
fn main() { fn main() {
let x = 'c'; let x = 'c';
match x { match x {
'a' ... 'j' => println!("early ASCII letter"), 'a' ... 'j' => println!("early ASCII letter"),
'k' ... 'z' => println!("late ASCII letter"), 'k' ... 'z' => println!("late ASCII letter"),
@ -235,7 +189,3 @@ not this:
```text ```text
4 | (5 if y) => ... 4 | (5 if y) => ...
``` ```
## Bindings
You can bind values to names with `@`: