// ./src/macros/designators.md macro_rules! create_function { // This macro takes an argument of designator `ident` and // creates a function named `$func_name`. // The `ident` designator is used for variable/function names. ($func_name:ident) => { fn $func_name() { // The `stringify!` macro converts an `ident` into a string. println!("You called {:?}()", stringify!($func_name)); } }; } // Create functions named `foo` and `bar` with the above macro. create_function!(foo); create_function!(bar); macro_rules! print_result { // This macro takes an expression of type `expr` and prints // it as a string along with its result. // The `expr` designator is used for expressions. ($expression:expr) => { // `stringify!` will convert the expression *as it is* into a string. println!("{:?} = {:?}", stringify!($expression), $expression); }; } fn part0() { foo(); bar(); print_result!(1u32 + 1); // Recall that blocks are expressions too! print_result!({ let x = 1u32; x * x + 2 * x - 1 }); } pub fn main() { part0(); }