Provides a way to define an interface (trait) in a crate, but can implement or use it in any crate. It 's usually used to solve the problem of circular dependencies between crates.

Example

// Define the interface
#[crate_interface::def_interface]
pub trait HelloIf {
fn hello(&self, name: &str, id: usize) -> String;
}

// Implement the interface in any crate
struct HelloIfImpl;

#[crate_interface::impl_interface]
impl HelloIf for HelloIfImpl {
fn hello(&self, name: &str, id: usize) -> String {
format!("Hello, {} {}!", name, id)
}
}

// Call `HelloIfImpl::hello` in any crate
use crate_interface::call_interface;
assert_eq!(
call_interface!(HelloIf::hello("world", 123)),
"Hello, world 123!"
);
assert_eq!(
call_interface!(HelloIf::hello, "rust", 456), // another calling style
"Hello, rust 456!"
);