rust - Unable to import/export macro -

i have module named macros.rs contains

/// macro implement fromerror. /// from_error!(myerror, ioerror, myerror::ioerror) macro_rules! from_error {     ( $t:ty, $err:ty, $name:path ) => {         use std;         impl std::error::fromerror<$err> $t {             fn from_error(err: $err) -> $t {                 $name(err)             }         }     } } 

in main.rs import module this

#[macro_use] mod macros; 

when try use from_error in other modules of project, compiler says error: macro undefined: 'from_error!'.

turns out order in declare modules matters.

mod json; // json uses macros "macros" module. can't find them. #[macro_use] mod macros;  #[macro_use] mod macros; mod json; // json uses macros "macros" module. everything's ok way.