Overload
Macros can be overloaded to accept different combinations of arguments.
In that regard, macro_rules!
can work similarly to a match block:
// `test!` will compare `$left` and `$right` // in different ways depending on how you invoke it: macro_rules! test { // Arguments don't need to be separated by a comma. // Any template can be used! ($left:expr; and $right:expr) => ( println!("{:?} and {:?} is {:?}", stringify!($left), stringify!($right), $left && $right) ); // ^ each arm must end with a semicolon. ($left:expr; or $right:expr) => ( println!("{:?} or {:?} is {:?}", stringify!($left), stringify!($right), $left || $right) ); } fn main() { test!(1i32 + 1 == 2i32; and 2i32 * 2 == 4i32); test!(true; or false); }