Attribute Macro define 

#[define]

This attribute defines a function-like macro based on the template module it annotated. One can define actual modules with variations by calling the defined macro with different arguments.

Example

// To define a module-defining macro that called `define_foo_mod`, and let
// the macro user to customize some functions in the module by specifying
// ways to construct variables (`BAR`), substitute attributes (along with
// extend the function signature) (`BAZ`), one can write:
#[mod_template::define(
    macro_rules! define_foo_mod;
    constructions(BAR -> impl crate::BarTrait),
    attribute_substitutions(BAZ)),
]
mod __ {
    #[__CONSTRUCT(bar as BAR)]
    #[__SUBSTITUTE(BAZ)]
    fn an_fn() {
        bar.do_something();
    }
}

// Call the defined macro to produce an actual module (named as `actual_foo`):
define_foo_mod! {
    mod actual_foo;
    constructions {
        BAR => crate::Bar::new(),
    },
    attribute_substitutions {
        BAZ => #[::baz::baz],
        // If one want to extend the signature of the function annotated by
        // `#[__SUBSTITUTE(BAZ)]`, use
        // `BAZ => #[::baz::baz] (.., qux: crate::Qux),`.
    },
}

See mod_template::define.