collections::borrow

Trait collections::borrow::Borrow [−] [src]

pub trait Borrow<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`Tare` are &T`&T(a shared borrow) and&mut T(a mutable borrow). But types likeVecprovide additional kinds of borrows: the borrowed slices&[T]and` and &mut [T]`&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`Borrowtrait: ifT: Borrow, then`, then &U`&Ucan be borrowed from&T. A given type can be borrowed as multiple different types. In particular,Vec: Borrow>and` and Vec<T>: Borrow<[T]>.

Borrow`Borrowis 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);

Implementors