Rust-Programming-Cookbook/Chapter06/sample_overloading_macro.rs

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Rust

//-- #########################
//-- Task: Overloading Macros
//-- Author: Vigneshwer.D
//-- Version: 1.0.0
//-- Date: 28 March 17
//-- #########################
// `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);
}