diff options
| -rw-r--r-- | rust.html.markdown | 11 |
1 files changed, 6 insertions, 5 deletions
diff --git a/rust.html.markdown b/rust.html.markdown index 71bc16b5..92794e69 100644 --- a/rust.html.markdown +++ b/rust.html.markdown @@ -92,10 +92,8 @@ fn main() { let s: String = "hello world".to_string(); // A string slice – an immutable view into another string - // This is basically an immutable pair of pointers to a string – it doesn’t - // actually contain the contents of a string, just a pointer to - // the begin and a pointer to the end of a string buffer, - // statically allocated or contained in another object (in this case, `s`) + // The string buffer can be statically allocated like in a string literal + // or contained in another object (in this case, `s`) let s_slice: &str = &s; println!("{} {}", s, s_slice); // hello world hello world @@ -290,7 +288,7 @@ fn main() { // Reference – an immutable pointer that refers to other data // When a reference is taken to a value, we say that the value has been ‘borrowed’. // While a value is borrowed immutably, it cannot be mutated or moved. - // A borrow lasts until the end of the scope it was created in. + // A borrow is active until the last use of the borrowing variable. let mut var = 4; var = 3; let ref_var: &i32 = &var; @@ -299,6 +297,8 @@ fn main() { println!("{}", *ref_var); // var = 5; // this would not compile because `var` is borrowed // *ref_var = 6; // this would not either, because `ref_var` is an immutable reference + ref_var; // no-op, but counts as a use and keeps the borrow active + var = 2; // ref_var is no longer used after the line above, so the borrow has ended // Mutable reference // While a value is mutably borrowed, it cannot be accessed at all. @@ -309,6 +309,7 @@ fn main() { println!("{}", *ref_var2); // 6 , // var2 would not compile. // ref_var2 is of type &mut i32, so stores a reference to an i32, not the value. // var2 = 2; // this would not compile because `var2` is borrowed. + ref_var2; // no-op, but counts as a use and keeps the borrow active until here } ``` |