История изменений

Паста из первой редакции Книги:

Strings will coerce into &str with an &:

fn takes_slice(slice: &str) {
    println!("Got: {}", slice);
}

fn main() {
    let s = "Hello".to_string();
    takes_slice(&s);
}

This coercion does not happen for functions that accept one of &str’s traits instead of &str. For example, TcpStream::connect has a parameter of type ToSocketAddrs. A &str is okay but a String must be explicitly converted using &*.

use std::net::TcpStream;

TcpStream::connect("192.168.0.1:3000"); // Parameter is of type &str.

let addr_string = "192.168.0.1:3000".to_string();
TcpStream::connect(&*addr_string); // Convert `addr_string` to &str.

Viewing a String as a &str is cheap, but converting the &str to a String involves allocating memory. No reason to do that unless you have to!

Паста из первой редакции Книги:

Strings will coerce into &str with an &:

fn takes_slice(slice: &str) {
    println!("Got: {}", slice);
}

fn main() {
    let s = "Hello".to_string();
    takes_slice(&s);
}

This coercion does not happen for functions that accept one of &str’s traits instead of &str. For example, TcpStream::connect has a parameter of type ToSocketAddrs. A &str is okay but a String must be explicitly converted using &*.

use std::net::TcpStream;

TcpStream::connect("192.168.0.1:3000"); // Parameter is of type &str.

let addr_string = "192.168.0.1:3000".to_string();
TcpStream::connect(&*addr_string); // Convert `addr_string` to &str.

Viewing a String as a &str is cheap, but converting the &str to a String involves allocating memory. No reason to do that unless you have to!