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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
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
abilities, so in this section, we'll cover all of the different things they can
do. Any of these abilities work in any place where a pattern is used.
in function arguments, and in `match` expressions. Patterns have a lot of
abilities, so in this section, we'll cover some of the most commonly used ones.
Any of these abilities work in any place where a pattern is used.
## Literals & _
@ -84,52 +84,6 @@ match name {
// 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
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
fn main() {
let x = 'c';
match x {
'a' ... 'j' => println!("early ASCII letter"),
'k' ... 'z' => println!("late ASCII letter"),
@ -235,7 +189,3 @@ not this:
```text
4 | (5 if y) => ...
```
## Bindings
You can bind values to names with `@`: