Rust Programming Cookbook

How to do it...

Let's implement some overloaded macros in a few simple steps:

1. Run cargo new macro-overloading --lib in Terminal (or PowerShell on Windows) and open the directory with Visual Studio Code.
2. In src/lib.rs, we add the following before the mod tests module declaration:

#![allow(unused_macros)]macro_rules! print_debug {    (stdout, $($o:expr),*) => {        $(print!("{:?}", $o));*;        println!();    };    (error, $($o:expr),*) => {        $(eprint!("{:?}", $o));*;        eprintln!();    };    ($stream:expr, $($o:expr),*) => {        $(let _ = write!($stream, "{:?}", $o));*;        let _ = writeln!($stream);    }}

3. Let's see how we apply this macro. Inside the tests module, let's see if the printer macro serializes strings to a stream by adding the following unit test (replace the existing ...