Macro init 

macro_rules! init {
    () => { ... };
}

Call all functions registered by call_on_init

Example

use std::sync::atomic::{AtomicUsize, Ordering};
static COUNTER: AtomicUsize = AtomicUsize::new(0);

#[init_hook::call_on_init]
unsafe fn init_once_unchecked() {
    COUNTER.fetch_add(1, Ordering::Release);
}

#[init_hook::call_on_init]
fn init_once() {
    COUNTER.fetch_add(1, Ordering::Release);
}

fn main() {
   init_hook::init!();
   assert_eq!(COUNTER.load(Ordering::Acquire), 2);
}

Panic

If init isn’t used in main exactly once, init_hook will detect this and panic pre-main

use std::sync::atomic::{AtomicBool, Ordering};
static INIT_CALLED: AtomicBool = AtomicBool::new(false);

#[init_hook::call_on_init]
fn init() {
    INIT_CALLED.store(true, Ordering::Release);
}

// This will panic with "`init_hook::init` must be used within the root main function"
fn main() {
   let _init_called = INIT_CALLED.load(Ordering::Acquire);
}