#[macro_export]
macro_rules! invoke_once {
    () => {
        unsafe {
            static mut __VALUE: bool = false;
            if __VALUE { false } else { __VALUE = true; true }
        }
    };

    // if this is used inside of an unsafe codeblock
    // use this branch to avoid the unnecessary unsafe block warning
    (unsafe) => {
        {
        static mut __VALUE: bool = false;
        if __VALUE { false } else { __VALUE = true; true }
        }
    }
}

pub struct OnDrop<F: FnOnce()>(Option<F>);

impl<F: FnOnce()> OnDrop<F> {
    pub fn new(fun: F) -> Self {
        Self(Some(fun))
    }
}

impl<F: FnOnce()> Drop for OnDrop<F> {
    fn drop(&mut self) {
        if let Some(fun) = self.0.take() {
            fun()
        }
    }
}