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Guide: Patterns: use non-x variables in match blocks

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This commit is contained in:
Piotr Szotkowski
2014-10-26 09:40:13 +01:00
parent f168c12c56
commit aa1cd6e707
1 changed files with 8 additions and 8 deletions
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src/doc/guide.md
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@@ -3801,7 +3801,7 @@ the value to a name with `@`:
let x = 1i; let x = 1i;
match x { match x {
x @ 1 ... 5 => println!("got {}", x), e @ 1 ... 5 => println!("got a range element {}", e),
_ => println!("anything"), _ => println!("anything"),
} }
``` ```
@@ -3834,7 +3834,7 @@ enum OptionalInt {
let x = Value(5i); let x = Value(5i);
match x { match x {
Value(x) if x > 5 => println!("Got an int bigger than five!"), Value(i) if i > 5 => println!("Got an int bigger than five!"),
Value(..) => println!("Got an int!"), Value(..) => println!("Got an int!"),
Missing => println!("No such luck."), Missing => println!("No such luck."),
} }
@@ -3847,12 +3847,12 @@ with. First, `&`:
let x = &5i; let x = &5i;
match x { match x {
&x => println!("Got a value: {}", x), &val => println!("Got a value: {}", val),
} }
``` ```
Here, the `x` inside the `match` has type `int`. In other words, the left hand Here, the `val` inside the `match` has type `int`. In other words, the left hand
side of the pattern destructures the value. If we have `&5i`, then in `&x`, `x` side of the pattern destructures the value. If we have `&5i`, then in `&val`, `val`
would be `5i`. would be `5i`.
If you want to get a reference, use the `ref` keyword: If you want to get a reference, use the `ref` keyword:
@@ -3861,11 +3861,11 @@ If you want to get a reference, use the `ref` keyword:
let x = 5i; let x = 5i;
match x { match x {
ref x => println!("Got a reference to {}", x), ref r => println!("Got a reference to {}", r),
} }
``` ```
Here, the `x` inside the `match` has the type `&int`. In other words, the `ref` Here, the `r` inside the `match` has the type `&int`. In other words, the `ref`
keyword _creates_ a reference, for use in the pattern. If you need a mutable keyword _creates_ a reference, for use in the pattern. If you need a mutable
reference, `ref mut` will work in the same way: reference, `ref mut` will work in the same way:
@@ -3873,7 +3873,7 @@ reference, `ref mut` will work in the same way:
let mut x = 5i; let mut x = 5i;
match x { match x {
ref mut x => println!("Got a mutable reference to {}", x), ref mut mr => println!("Got a mutable reference to {}", mr),
} }
``` ```