Macro format_buf::format

macro_rules! format {
    () => { ... };
    ($lit:literal $($arg:tt)*) => { ... };
    ($buf:expr, $lit:literal $($arg:tt)*) => { ... };
}

A drop-in replacement for std::format!, which can optionally accept a an existing String buffer.

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.\
")