可以使用 Rust 宏生成一些名称来自向量的函数吗？

Question

if I want to generate some functions using a macro, it is going to be like this:

macro_rules! generate_some_funcs {
    ($($func:ident),*) => {
        $(
            fn $func() {
                println!("I'm a function and my name is {}", stringify!($func));
            }
        )*
    }
}

generate_some_funcs!(a, b, c, d);

But, What if function names cames from a vector, array, or anything else? Is it possible?

fn main() {
  let func_names = vec!["a", "b", "c", "d"];

  generates_funcs!(func_names);
}

Answer 1

Function names cannot come from a vector, because vectors don't exist until runtime, and macros are evaluated at compile time. There isn't a syntax for iterating arrays in macros either.

What you can do is have the macro generate both the functions and the array. This way you don't have to duplicate the names.

macro_rules! generate_functions {
    ($var:ident => $($func:ident),*) => {
        $(
            fn $func() {
                println!("I'm a function and my name is {}", stringify!($func));
            }
        )*

        let $var = [$(stringify!($func)),*];
    }
}

fn main() {
    generate_functions!(func_names => a, b, c, d);

    a();
    b();
    c();
    d();

    assert_eq!(func_names, ["a", "b", "c", "d"]);
}