Rust Programming Cookbook

How to do it...

Automated testing with macros is only a few steps away:

1. Run cargo new dry-macros --lib in Terminal (or PowerShell on Windows) and open the directory with Visual Studio Code.
2. In src/lib.rs, we want to create a helper macro and import the stuff we need:

use std::ops::{Add, Mul, Sub};macro_rules! assert_equal_len {    // The `tt` (token tree) designator is used for    // operators and tokens.    ($a:ident, $b: ident, $func:ident) => (        assert_eq!($a.len(), $b.len(),                "{:?}: dimension mismatch: {:?} {:?}",                stringify!($func),                ($a.len(),),                ($b.len(),));    )}

3. Next, we define a macro to auto-implement an operator. Let's add this underneath the assert_equal_len macro:

macro_rules! op {    ($func:ident, $bound:ident, $method:ident) => ( pub fn ...