## Keyboard shortcuts

Press `←` or `→` to navigate between chapters

Press `S` or `/` to search in the book

Press `?` to show this help

Press `Esc` to hide this help

# 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);
    }