Trait collections::borrow::Borrow
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pub trait Borrow<Borrowed> where Borrowed: ?Sized {
fn borrow(&self) -> &Borrowed;
}A trait for borrowing data.
In general, there may be several ways to "borrow" a piece of data. The
typical ways of borrowing a type T are &T (a shared borrow) and &mut T
(a mutable borrow). But types like Vec<T> provide additional kinds of
borrows: the borrowed slices &[T] and &mut [T].
When writing generic code, it is often desirable to abstract over all ways
of borrowing data from a given type. That is the role of the Borrow
trait: if T: Borrow<U>, then &U can be borrowed from &T. A given
type can be borrowed as multiple different types. In particular, Vec<T>: Borrow<Vec<T>> and Vec<T>: Borrow<[T]>.
If you are implementing Borrow and both Self and Borrowed implement
Hash, Eq, and/or Ord, they must produce the same result.
Borrow is very similar to, but different than, AsRef. See
the book for more.
Required Methods
fn borrow(&self) -> &Borrowed
Immutably borrows from an owned value.
Examples
fn main() { use std::borrow::Borrow; fn check<T: Borrow<str>>(s: T) { assert_eq!("Hello", s.borrow()); } let s = "Hello".to_string(); check(s); let s = "Hello"; check(s); }use std::borrow::Borrow; fn check<T: Borrow<str>>(s: T) { assert_eq!("Hello", s.borrow()); } let s = "Hello".to_string(); check(s); let s = "Hello"; check(s);