Attribute Macro core_extensions::macro_attr

#[macro_attr]

Available on crate feature macro_utils only.

For using function-like macros as attributes.

Examples

Module

use core_extensions::macro_attr;
 
fn main() {
    assert_eq!(hello::Hello(3, 5).sum(), 8);
    assert_eq!(hello::Hello(13, 21).sum(), 34);
}
 
#[macro_attr(in_mod!(pub mod hello;))]
#[derive(Debug, PartialEq)]
pub struct Hello(pub u32, pub u32);
 
impl hello::Hello {
    const fn sum(&self) -> u64 {
        self.0 as u64 + self.1 as u64
    }
}
 
#[macro_export]
macro_rules! in_mod {
    (
        $(#[$attr:meta])*
        $vis:vis mod $module:ident;
         
        $($item:item)*
    ) => {
        $(#[$attr])*
        $vis mod $module {
            $($item)*
        }
    }
}
 

Item count

This example only works from 1.46.0 onwards, not sure why.

use core_extensions::macro_attr;
 
fn main() {
    assert_eq!(items::COUNT, 4);

    assert_eq!(items::foo(), 3);
    assert_eq!(items::BAR, 5);
}
 
#[macro_attr(crate::and_item_count)]
pub mod items {
    pub fn foo() -> u32 {
        3
    }

    pub const BAR: u32 = 5;
     
    pub struct Baz;

    pub struct Qux {
        pub x: u64,
        pub y: u64,
    }
}
 
#[macro_export]
macro_rules! and_item_count {
    (
        $(#[$attr:meta])*
        $vis:vis mod $module:ident {
            $($item:item)*
        }
    ) => {
        $(#[$attr])*
        $vis mod $module {
            pub const COUNT: usize = $crate::__::count_tts!(($($item)*));
             
            $($item)*
        }
    }
}
 
#[doc(hidden)]
mod __ {
    pub use core_extensions::count_tts;
}