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Merge pull request #746 from authchir/patch-1

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Use the assumed 'static lifetime in static variables
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Carol (Nichols || Goulding)
2017-06-06 14:17:28 -04:00
committed by GitHub
parent aed51c5391 681b0aaf0a
commit 4be2cdf039
1 changed files with 7 additions and 5 deletions
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second-edition/src/ch19-01-unsafe-rust.md
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@@ -392,7 +392,7 @@ declaration and use of a static variable with a string slice as a value:
<span class="filename">Filename: src/main.rs</span>
```rust
static HELLO_WORLD: &'static str = "Hello, world!";
static HELLO_WORLD: &str = "Hello, world!";
fn main() {
println!("name is: {}", HELLO_WORLD);
@@ -405,10 +405,12 @@ variable</span>
`static` variables are similar to constants: their names are also in
`SCREAMING_SNAKE_CASE` by convention, and we *must* annotate the variable's
type, which is `&'static str` in this case. Only references with the `'static`
lifetime may be stored in a static variable. Accessing immutable static
variables is safe. Values in a static variable have a fixed address in memory,
and using the value will always access the same data. Constants, on the other
hand, are allowed to duplicate their data whenever they are used.
lifetime may be stored in a static variable. Because of this, the Rust compiler
can figure out the lifetime by itself and we don't need to annotate it explicitly.
Accessing immutable static variables is safe. Values in a static variable have a
fixed address in memory, and using the value will always access the same data.
Constants, on the other hand, are allowed to duplicate their data whenever they
are used.
Another way in which static variables are different from constants is that
static variables can be mutable. Both accessing and modifying mutable static