概述

是std::format!的替换方案，可选地接受一个现有的String缓冲区。

use format_buf::format;

let mut buf = format!("Roses are {},\n", "red");
let () = format!(buf, "Violets are {}.", "blue");
assert_eq!(buf, "\
    Roses are red,\n\
    Violets are blue.\
")