//! Defer a close to be ran on drop.

use std::{
    ops::Drop,
};

pub struct Defer<F>(Option<F>)
where F: FnOnce() -> ();

impl<F> Defer<F>
where F: FnOnce()
{
    #[cfg(nightly)]
    #[inline] pub const fn new(from: F) -> Self
    {
	Self(Some(from))
    }
    #[cfg(not(nightly))] 
    #[inline] pub fn new(from: F) -> Self
    {
	Self(Some(from))
    }
    pub fn forget(mut self) -> F
    {
	let value = self.0.take();
	std::mem::forget(self);
	value.unwrap()
    }
    #[inline] pub fn now(self) {}
}

impl<F> Drop for Defer<F>
where F: FnOnce()
{
    fn drop(&mut self)
    {
	self.0.take().unwrap()();
    }
}